@article{strayer-scherer_sharpe_louws_meadows_2024, title={Evaluation of systemic acquired resistance inducers for the management of copper and streptomycin resistant strains of<i> Xanthomonas</i><i> perforans</i> on tomato}, volume={175}, ISSN={["1873-6904"]}, url={https://doi.org/10.1016/j.cropro.2023.106430}, DOI={10.1016/j.cropro.2023.106430}, abstractNote={Bacterial spot (Xanthomonas spp.) is one of the most detrimental diseases of tomato (Solanum lycopersicum L.) worldwide. Bacterial spot Xanthomonads are either endemic or spread by contaminated seed or transplant material into tomato production areas. Due to limited disease management options, transplant producers rely on copper- and streptomycin-based bactericides that are often ineffective due to the predominance of resistant Xanthomonas strains. In this study, transplant production facilities located across eight counties in western North Carolina were surveyed for bacterial spot symptoms from 2018 to 2019. In total, 29 strains (n = 6 in 2018 and n = 23 in 2019) were isolated and identified as Xanthomonas perforans. All strains were resistant to copper, while only 24% of the strains were resistant to streptomycin. Therefore, the ability of three systemic acquired resistance (SAR) inducers, methyl salicylate, Bacillus mycoides isolate J, and acibenzolar-S-methyl (ASM), alone or in combination with copper or streptomycin were evaluated as potential alternatives to copper-mancozeb (grower standard) to manage bacterial spot under greenhouse and field conditions. Under greenhouse conditions, applications of ASM at 0.4 g/L alone, or in combination with copper or streptomycin, significantly reduced bacterial spot disease severity when compared to the grower standard and nontreated controls (P < 0.05). However, none of the SAR inducers significantly reduced disease severity or improved yield when compared to copper-mancozeb-ASM under field conditions (P < 0.05). This study highlights the potential of using ASM for the management of bacterial spot of tomato transplant production to reduce bacterial spot introduction into the field.}, journal={CROP PROTECTION}, author={Strayer-Scherer, Amanda L. and Sharpe, Suzette R. and Louws, Frank J. and Meadows, Inga M.}, year={2024}, month={Jan} }
 @article{adhikari_olukolu_paudel_pandey_halterman_louws_2024, title={Genotyping-by-Sequencing Reveals Population Differentiation and Linkage Disequilibrium in <i>Alternaria linariae</i> from Tomato}, volume={2}, ISSN={["1943-7684"]}, DOI={10.1094/PHYTO-07-23-0229-R}, abstractNote={ Alternaria linariae is an economically important foliar pathogen that causes early blight disease in tomatoes. Understanding genetic diversity, population genetic structure, and evolutionary potential is crucial to contemplating effective disease management strategies. We leveraged genotyping-by-sequencing (GBS) technology to compare genome-wide variation in 124 isolates of Alternaria spp. ( A. alternata, A. linariae, and A. solani) for comparative genome analysis and to test the hypotheses of genetic differentiation and linkage disequilibrium (LD) in A. linariae collected from tomatoes in western North Carolina. We performed a pangenome-aware variant calling and filtering with GBSapp and identified 53,238 variants conserved across the reference genomes of three Alternaria spp. The highest marker density was observed on chromosome 1 (7 Mb). Both discriminant analysis of principal components and Bayesian model-based STRUCTURE analysis of A. linariae isolates revealed three subpopulations with minimal admixture. The genetic differentiation coefficients (FST) within A. linariae subpopulations were similar and high (0.86), indicating that alleles in the subpopulations are fixed and the genetic structure is likely due to restricted recombination. Analysis of molecular variance indicated higher variation among populations (89%) than within the population (11%). We found long-range LD between pairs of loci in A. linariae, supporting the hypothesis of low recombination expected for a fungal pathogen with limited sexual reproduction. Our findings provide evidence of a high level of population genetic differentiation in A. linariae, which reinforces the importance of developing tomato varieties with broad-spectrum resistance to various isolates of A. linariae. }, journal={PHYTOPATHOLOGY}, author={Adhikari, Tika B. and Olukolu, Bode A. and Paudel, Rajan and Pandey, Anju and Halterman, Dennis and Louws, Frank J.}, year={2024}, month={Feb} }
 @article{siddique_silverman_louws_panthee_2024, title={Quantitative Trait Loci Mapping for Bacterial Wilt Resistance and Plant Height in Tomatoes}, volume={13}, ISSN={["2223-7747"]}, url={https://doi.org/10.3390/plants13060876}, DOI={10.3390/plants13060876}, abstractNote={Bacterial wilt (BW) of tomatoes, caused by Ralstonia solanacearum, is a devastating disease that results in large annual yield losses worldwide. Management of BW of tomatoes is difficult due to the soil-borne nature of the pathogen. One of the best ways to mitigate the losses is through breeding for disease resistance. Moreover, plant height (PH) is a crucial element related to plant architecture, which determines nutrient management and mechanical harvesting in tomatoes. An intraspecific F2 segregating population (NC 11212) of tomatoes was developed by crossing NC 84173 (tall, BW susceptible) × CLN1466EA (short, BW resistant). We performed quantitative trait loci (QTL) mapping using single nucleotide polymorphic (SNP) markers and the NC 11212 F2 segregating population. The QTL analysis for BW resistance revealed a total of three QTLs on chromosomes 1, 2, and 3, explaining phenotypic variation (R2) ranging from 3.6% to 14.9%, whereas the QTL analysis for PH also detected three QTLs on chromosomes 1, 8, and 11, explaining R2 ranging from 7.1% to 11%. This work thus provides information to improve BW resistance and plant architecture-related traits in tomatoes.}, number={6}, journal={PLANTS-BASEL}, author={Siddique, Muhammad Irfan and Silverman, Emily and Louws, Frank and Panthee, Dilip R.}, year={2024}, month={Mar} }
 @article{adhikari_siddique_louws_panthee_2023, title={Identification of quantitative trait loci associated with bacterial spot race T4 resistance in intra-specific populations of tomato (Solanum lycopersicum L.)}, volume={18}, ISSN={1932-6203}, url={http://dx.doi.org/10.1371/journal.pone.0295551}, DOI={10.1371/journal.pone.0295551}, abstractNote={Bacterial spot of tomato is a serious disease caused by at least four species and four races of Xanthomonas- X. euvesicatoria (race T1), X. vesicatoria (race T2), X. perforans (race T3 and T4), and X. gardneri, with X. perforans race T4 being predominant in the southeast USA. Practical management of this disease is challenging because of the need for more effective chemicals and commercially resistant cultivars. Identification of genetic resistance is the first step to developing a disease-resistant variety. The objective of this study was to identify quantitative trait loci (QTL) conferring resistance to race T4 in two independent recombinant inbred lines (RILs) populations NC 10204 (intra-specific) and NC 13666 (interspecific) developed by crossing NC 30P x NC22L-1(2008) and NC 1CELBR x PI 270443, respectively. Seven QTLs on chromosomes 2, 6, 7, 11, and 12 were identified in NC 10204. The QTL on chromosome 6 explained the highest percentage of phenotypic variance (up to 21.3%), followed by the QTL on chromosome 12 (up to 8.2%). On the other hand, the QTLs on chromosomes 1, 3, 4, 6, 7, 8, 9, and 11 were detected in NC 13666. The QTLs on chromosomes 6, 7, and 11 were co-located in NC 10204 and NC 13666 populations. The donor of the resistance associated with these QTL in NC 10204 is a released breeding line with superior horticultural traits. Therefore, both the donor parent and the QTL information will be useful in tomato breeding programs as there will be minimal linkage drag associated with the bacterial spot resistance.}, number={12}, journal={PLOS ONE}, publisher={Public Library of Science (PLoS)}, author={Adhikari, Pragya and Siddique, Muhammad Irfan and Louws, Frank J. and Panthee, Dilip R.}, editor={Pandey, Abhay K.Editor}, year={2023}, month={Dec}, pages={e0295551} }
 @article{adhikari_siddique_louws_sim_panthee_2023, title={Molecular mapping of quantitative trait loci for resistance to early blight in tomatoes}, volume={14}, ISSN={1664-462X}, url={http://dx.doi.org/10.3389/fpls.2023.1135884}, DOI={10.3389/fpls.2023.1135884}, abstractNote={Early blight (EB), caused by Alternaria linariae (Neerg.) (syn. A. tomatophila) Simmons, is a disease that affects tomatoes (Solanum lycopersicum L.) throughout the world, with tremendous economic implications. The objective of the present study was to map the quantitative trait loci (QTL) associated with EB resistance in tomatoes. The F2 and F2:3 mapping populations consisting of 174 lines derived from NC 1CELBR (resistant) × Fla. 7775 (susceptible) were evaluated under natural conditions in the field in 2011 and in the greenhouse in 2015 by artificial inoculation. In all, 375 Kompetitive Allele Specific PCR (KASP) assays were used for genotyping parents and the F2 population. The broad-sense heritability estimate for phenotypic data was 28.3%, and 25.3% for 2011, and 2015 disease evaluations, respectively. QTL analysis revealed six QTLs associated with EB resistance on chromosomes 2, 8, and 11 (LOD 4.0 to 9.1), explaining phenotypic variation ranging from 3.8 to 21.0%. These results demonstrate that genetic control of EB resistance in NC 1CELBR is polygenic. This study may facilitate further fine mapping of the EB-resistant QTL and marker-assisted selection (MAS) to transfer EB resistance genes into elite tomato varieties, including broadening the genetic diversity of EB resistance in tomatoes.}, journal={Frontiers in Plant Science}, publisher={Frontiers Media SA}, author={Adhikari, Tika B. and Siddique, Muhammad Irfan and Louws, Frank J. and Sim, Sung-Chur and Panthee, Dilip R.}, year={2023}, month={May} }
 @article{oh_ingram_shekasteband_adhikari_louws_dean_2023, title={Tissues and mechanisms associated with Verticillium wilt resistance in tomato using bi-grafted near-isogenic lines}, volume={5}, ISSN={["1460-2431"]}, url={https://doi.org/10.1093/jxb/erad182}, DOI={10.1093/jxb/erad182}, abstractNote={Abstract}, number={15}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Oh, Yeonyee and Ingram, Thomas and Shekasteband, Reza and Adhikari, Tika and Louws, Frank J. and Dean, Ralph A.}, editor={Höfte, MonicaEditor}, year={2023}, month={May} }
 @article{advancing disease management strategies for root-knot nematodes (meloidogyne spp.) on tomato_2022, url={https://publons.com/wos-op/publon/56007329/}, journal={Phytopathology}, year={2022} }
 @article{evaluating diverse tomato genotypes for resistance to root-knot nematode, meloidogyne enterolobii_2022, url={https://publons.com/wos-op/publon/63443543/}, journal={Phytopathology}, year={2022} }
 @article{planas-marques_kressin_kashyap_panthee_louws_coll_valls_2022, title={Four bottlenecks restrict colonization and invasion by the pathogen Ralstonia solanacearum in resistant tomato (vol 71, pg 2157, 2020)}, volume={3}, ISSN={["1460-2431"]}, url={https://publons.com/wos-op/publon/56007363/}, DOI={10.1093/jxb/erac086}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Planas-Marques, Marc and Kressin, Jonathan P. and Kashyap, Anurag and Panthee, Dilip R. and Louws, Frank J. and Coll, Nuria S. and Valls, Marc}, year={2022}, month={Mar} }
 @article{adhikari_aryal_redpath_broeck_ashrafi_philbrick_jacobs_sozzani_louws_2022, title={RNA-Seq and Gene Regulatory Network Analyses Uncover Candidate Genes in the Early Defense to Two Hemibiotrophic Colletorichum spp. in Strawberry}, volume={12}, ISSN={["1664-8021"]}, DOI={10.3389/fgene.2021.805771}, abstractNote={Two hemibiotrophic pathogens, Colletotrichum acutatum (Ca) and C. gloeosporioides (Cg), cause anthracnose fruit rot and anthracnose crown rot in strawberry (Fragaria × ananassa Duchesne), respectively. Both Ca and Cg can initially infect through a brief biotrophic phase, which is associated with the production of intracellular primary hyphae that can infect host cells without causing cell death and establishing hemibiotrophic infection (HBI) or quiescent (latent infections) in leaf tissues. The Ca and Cg HBI in nurseries and subsequent distribution of asymptomatic infected transplants to fruit production fields is the major source of anthracnose epidemics in North Carolina. In the absence of complete resistance, strawberry varieties with good fruit quality showing rate-reducing resistance have frequently been used as a source of resistance to Ca and Cg. However, the molecular mechanisms underlying the rate-reducing resistance or susceptibility to Ca and Cg are still unknown. We performed comparative transcriptome analyses to examine how rate-reducing resistant genotype NCS 10-147 and susceptible genotype ‘Chandler’ respond to Ca and Cg and identify molecular events between 0 and 48 h after the pathogen-inoculated and mock-inoculated leaf tissues. Although plant response to both Ca and Cg at the same timepoint was not similar, more genes in the resistant interaction were upregulated at 24 hpi with Ca compared with those at 48 hpi. In contrast, a few genes were upregulated in the resistant interaction at 48 hpi with Cg. Resistance response to both Ca and Cg was associated with upregulation of MLP-like protein 44, LRR receptor-like serine/threonine-protein kinase, and auxin signaling pathway, whereas susceptibility was linked to modulation of the phenylpropanoid pathway. Gene regulatory network inference analysis revealed candidate transcription factors (TFs) such as GATA5 and MYB-10, and their downstream targets were upregulated in resistant interactions. Our results provide valuable insights into transcriptional changes during resistant and susceptible interactions, which can further facilitate assessing candidate genes necessary for resistance to two hemibiotrophic Colletotrichum spp. in strawberry.}, journal={FRONTIERS IN GENETICS}, author={Adhikari, Tika B. and Aryal, Rishi and Redpath, Lauren E. and Broeck, Lisa and Ashrafi, Hamid and Philbrick, Ashley N. and Jacobs, Raymond L. and Sozzani, Rosangela and Louws, Frank J.}, year={2022}, month={Mar} }
 @article{screening of tomato lines for late blight resistance_2022, url={https://publons.com/wos-op/publon/58280896/}, journal={Hortscience}, year={2022} }
 @article{genetic and genomic analysis of race determination and resistance to verticillium dahliae in tomato_2021, url={https://publons.com/wos-op/publon/56007335/}, journal={Phytopathology}, year={2021} }
 @article{genetic diversity and population structure of <i>alternaria</i> species infecting tomato and potato in north carolina and wisconsin_2021, url={https://publons.com/wos-op/publon/56007330/}, journal={Phytopathology}, year={2021} }
 @article{adhikari_muzhinji_halterman_louws_2021, title={Genetic diversity and population structure of Alternaria species from tomato and potato in North Carolina and Wisconsin}, volume={11}, url={http://dx.doi.org/10.1038/s41598-021-95486-6}, DOI={10.1038/s41598-021-95486-6}, abstractNote={Abstract}, number={1}, journal={Scientific Reports}, publisher={Springer Science and Business Media LLC}, author={Adhikari, Tika B. and Muzhinji, Norman and Halterman, Dennis and Louws, Frank J.}, year={2021}, month={Dec} }
 @article{huber_louws_hernandez_2021, title={Impact of Different Daily Light Integrals and Carbon Dioxide Concentrations on the Growth, Morphology, and Production Efficiency of Tomato Seedlings}, volume={12}, ISSN={["1664-462X"]}, url={http://dx.doi.org/10.3389/fpls.2021.615853}, DOI={10.3389/fpls.2021.615853}, abstractNote={Indoor growing systems with light-emitting diodes offer advantages for the growth of tomato seedlings through uniform and optimized environmental conditions which increase consistency between plants and growing cycles. CO2 enrichment has been shown to improve the yield of crops. Thus, this research aimed to characterize the effects of varied light intensities and CO2 enrichment on the growth, morphology, and production efficiency of tomato seedlings in indoor growing systems. Four tomato cultivars, “Florida-47 R,” “Rebelski,” “Maxifort,” and “Shin Cheong Gang,” were subjected to three different daily light integrals (DLIs) of 6.5, 9.7, and 13 mol m–2 d–1 with a percent photon flux ratio of 40 blue:60 red and an end-of-day far-red treatment of 5 mmol m–2 d–1. The plants were also subjected to three different CO2 concentrations: 448 ± 32 (400-ambient), 1010 ± 45 (1000), and 1568 ± 129 (1600) μmol mol–1. Temperature was maintained at 24.3°C ± 0.48/16.8°C ± 1.1 (day/dark; 22.4°C average) and relative humidity at 52.56 ± 8.2%. Plant density was 1000 plants m–2 until canopy closure. Morphological measurements were conducted daily to observe the growth response over time. In addition, data was collected to quantify the effects of each treatment. The results showed increases in growth rate with increases in the DLI and CO2 concentration. In addition, CO2 enrichment to 1000–1600 μmol mol–1 increased the light use efficiency (gDM mol–1applied) by 38–44%, and CO2 enrichment to 1600 μmol mol–1 did not result in any additional increase on shoot fresh mass, shoot dry mass, and stem extension. However, the net photosynthetic rate obtained with 1600 μmol mol–1 was 31 and 68% higher than those obtained with 1000 and 400 μmol mol–1, respectively. Furthermore, the comparison of the light and CO2 treatment combinations with the control (13 mol m–2 d–1–400CO2) revealed that the plants subjected to 6.5DLI–1600CO2, 9.7DLI–1000CO2, and 9.7DLI–1600CO2 treatment combinations exhibited the same growth rate as the control plants but with 25–50% less DLI. Furthermore, two treatment combinations (13.0DLI–1000CO2 and 13.0DLI–1600CO2) were associated with the consumption of comparable amount of energy but increased plant growth by 24–33%.}, journal={FRONTIERS IN PLANT SCIENCE}, publisher={Frontiers Media SA}, author={Huber, Brandon M. and Louws, Frank J. and Hernandez, Ricardo}, year={2021}, month={Mar} }
 @article{suchoff_jackson_gunter_schultheis_louws_2021, title={Non-destructive characterization of grafted tomato root systems using the mini-horhizotron}, volume={1302}, ISSN={["2406-6168"]}, url={https://publons.com/wos-op/publon/56007334/}, DOI={10.17660/ActaHortic.2021.1302.28}, journal={II INTERNATIONAL SYMPOSIUM ON VEGETABLE GRAFTING}, author={Suchoff, D. H. and Jackson, B. E. and Gunter, C. C. and Schultheis, J. R. and Louws, F. J.}, year={2021}, pages={209–214} }
 @article{ingram_sharpe_louws_meadows_2021, title={Pruning reduces yields in grafted tomatoes planted in the field}, volume={1302}, ISSN={["2406-6168"]}, url={https://publons.com/wos-op/publon/56007336/}, DOI={10.17660/ActaHortic.2021.1302.9}, journal={II INTERNATIONAL SYMPOSIUM ON VEGETABLE GRAFTING}, author={Ingram, T. and Sharpe, S. and Louws, F. J. and Meadows, I}, year={2021}, pages={65–71} }
 @article{adhikari_adhikari_louws_panthee_2020, title={Advances and Challenges in Bacterial Spot Resistance Breeding in Tomato (Solanum lycopersicum L.)}, volume={21}, ISSN={1422-0067}, url={http://dx.doi.org/10.3390/ijms21051734}, DOI={10.3390/ijms21051734}, abstractNote={Bacterial spot is a serious disease of tomato caused by at least four species of Xanthomonas. These include X. euvesicatoria (race T1), X. vesicatoria (race T2), X. perforans (races T3 and T4), and X. gardneri, with the distinct geographical distribution of each group. Currently, X. gardneri and X. perforans are two major bacterial pathogens of tomato in North America, with X. perforans (race T4) dominating in east-coast while X. gardneri dominating in the Midwest. The disease causes up to 66% yield loss. Management of this disease is challenging due to the lack of useful chemical control measures and commercial resistant cultivars. Although major genes for resistance (R) and quantitative resistance have been identified, breeding tomato for resistance to bacterial spot has been impeded by multiple factors including the emergence of new races of the pathogen that overcome the resistance, multigenic control of the resistance, linkage drag, non-additive components of the resistance and a low correlation between seedling assays and field resistance. Transgenic tomato with Bs2 and EFR genes was effective against multiple races of Xanthomonas. However, it has not been commercialized because of public concerns and complex regulatory processes. The genomics-assisted breeding, effectors-based genomics breeding, and genome editing technology could be novel approaches to achieve durable resistance to bacterial spot in tomato. The main goal of this paper is to understand the current status of bacterial spot of tomato including its distribution and pathogen diversity, challenges in disease management, disease resistance sources, resistance genetics and breeding, and future prospectives with novel breeding approaches.}, number={5}, journal={International Journal of Molecular Sciences}, publisher={MDPI AG}, author={Adhikari, Pragya and Adhikari, Tika B. and Louws, Frank J. and Panthee, Dilip R.}, year={2020}, month={Mar}, pages={1734} }
 @article{jacobs_adhikari_pattison_yencho_fernandez_louws_2020, title={Assessing Rate-Reducing Foliar Resistance to Anthracnose Crown Rot and Fruit Rot in Strawberry}, volume={104}, ISSN={0191-2917 1943-7692}, url={http://dx.doi.org/10.1094/PDIS-04-19-0687-RE}, DOI={10.1094/pdis-04-19-0687-re}, abstractNote={ Anthracnose fruit rot and anthracnose crown rot (ACR) caused by two species complexes of the fungus referred to as Colletotrichum acutatum and Colletotrichum gloeosporioides, respectively, are major pathogens of strawberry in North Carolina. Anthracnose epidemics are common when susceptible cultivars and asymptomatic planting stocks carrying quiescent Colletotrichum infection or hemibiotrophic infection (HBI) are planted. The main objective of this study was to assess resistance to HBI and ACR in strawberry. Strawberry cultivars and breeding lines were spray inoculated with isolates of C. acutatum or C. gloeosporioides. Four epidemiological parameters providing estimates of rate-reducing resistance to HBI and ACR in strawberry cultivars and lines were evaluated in repeated experiments in controlled environments in a greenhouse. HBI severity, measured as the percentage of total leaf area covered by acervuli, was estimated visually and by image analysis. ACR severity was rated weekly for wilt symptoms, and relative area under disease progress curve scores were calculated for comparing strawberry cultivars and lines. Significant differences (P ≤ 0.005) in HBI severity were found among strawberry genotypes; however, the correlations were not remarkable between Colletotrichum species (r = 0.4251). Although significant variation in resistance was observed for ACR, this was also weakly correlated (r = 0.2430) with resistance to C. gloeosporioides HBI. Overall, rate-reducing resistance to HBI and ACR in strawberry identified in this study could be utilized in breeding programs to develop durable resistance to anthracnose in North Carolina. }, number={2}, journal={Plant Disease}, publisher={Scientific Societies}, author={Jacobs, Raymond L. and Adhikari, Tika B. and Pattison, Jeremy and Yencho, G. Craig and Fernandez, Gina E. and Louws, Frank J.}, year={2020}, month={Feb}, pages={398–407} }
 @article{gottwald_poole_mccollum_hall_hartung_bai_luo_posny_duan_taylor_et al._2020, title={Canine olfactory detection of a vectored phytobacterial pathogen, Liberibacter asiaticus, and integration with disease control}, volume={117}, ISSN={["0027-8424"]}, url={https://publons.com/wos-op/publon/39596623/}, DOI={10.1073/pnas.1914296117}, abstractNote={
            Early detection and rapid response are crucial to avoid severe epidemics of exotic pathogens. However, most detection methods (molecular, serological, chemical) are logistically limited for large-scale survey of outbreaks due to intrinsic sampling issues and laboratory throughput. Evaluation of 10 canines trained for detection of a severe exotic phytobacterial arboreal pathogen,
            Candidatus
            Liberibacter asiaticus (
            C
            Las), demonstrated 0.9905 accuracy, 0.8579 sensitivity, and 0.9961 specificity. In a longitudinal study, cryptic
            C
            Las infections that remained subclinical visually were detected within 2 wk postinfection compared with 1 to 32 mo for qPCR. When allowed to interrogate a diverse range of in vivo pathogens infecting an international citrus pathogen collection, canines only reacted to Liberibacter pathogens of citrus and not to other bacterial, viral, or spiroplasma pathogens. Canines trained to detect
            C
            Las-infected citrus also alerted on
            C
            Las-infected tobacco and periwinkle,
            C
            Las-bearing psyllid insect vectors, and
            C
            Las cocultured with other bacteria but at
            C
            Las titers below the level of molecular detection. All of these observations suggest that canines can detect
            C
            Las directly rather than only host volatiles produced by the infection. Detection in orchards and residential properties was real time, ∼2 s per tree. Spatiotemporal epidemic simulations demonstrated that control of pathogen prevalence was possible and economically sustainable when canine detection was followed by intervention (i.e., culling infected individuals), whereas current methods of molecular (qPCR) and visual detection failed to contribute to the suppression of an exponential trajectory of infection.
          }, number={7}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Gottwald, Timothy and Poole, Gavin and McCollum, Thomas and Hall, David and Hartung, John and Bai, Jinhe and Luo, Weiqi and Posny, Drew and Duan, Yong-Ping and Taylor, Earl and et al.}, year={2020}, month={Feb}, pages={3492–3501} }
 @article{ingram_oh_adhikari_louws_dean_2020, title={Comparative Genome Analyses of 18 Verticillium dahliae Tomato Isolates Reveals Phylogenetic and Race Specific Signatures}, volume={11}, ISSN={["1664-302X"]}, DOI={10.3389/fmicb.2020.573755}, abstractNote={Host resistance is one of the few strategies available to combat the soil borne pathogenic fungus Verticillium dahliae. Understanding pathogen diversity in populations is key to successfully deploying host resistance. In this study the genomes of 18 V. dahliae isolates of races 1 (n = 2), 2 (n = 4), and 3 (n = 12) from Japan, California, and North Carolina were sequenced and mapped to the reference genome of JR2 (from tomato). The genomes were analyzed for phylogenetic and pathogen specific signatures to classify specific strains or genes for future research. Four highly clonal lineages/groups were discovered, including a lineage unique to North Carolina isolates, which had the rare MAT1-1 mating type. No evidence for recombination between isolates of different mating types was observed, even in isolates of different mating types discovered in the same field. By mapping these 18 isolates genomes to the JR2 reference genome, 193 unique candidate effectors were found using SignalP and EffectorP. Within these effectors, 144 highly conserved effectors, 42 mutable effectors (truncated or present in some isolates but absent in others), and 7 effectors present in highly variable regions of the chromosomes were discovered. Of the 144 core effectors, 21 were highly conserved in V. alfalfae and V. longisporum, 7 of which have no known function. Within the non-core effectors 30 contained large numbers of non-synonymous mutations, while 15 of them contained indels, frameshift mutations, or were present on highly variable regions of the chromosome. Two of these highly variable region effectors (HVREs) were only present in race 2 isolates, but not in race 3 isolates. The race 1 effector Ave1 was also present in a highly variable region. These data may suggest that these highly variable regions are enriched in race determinant genes, consistent with the two-speed genome hypothesis.}, journal={FRONTIERS IN MICROBIOLOGY}, author={Ingram, Thomas W. and Oh, Yeonyee and Adhikari, Tika B. and Louws, Frank J. and Dean, Ralph A.}, year={2020}, month={Nov} }
 @article{interdisciplinary synergies to advance plant health in horticultural systems_2020, url={https://publons.com/wos-op/publon/56007331/}, journal={Hortscience}, year={2020} }
 @misc{philbrick_adhikari_louws_gorny_2020, title={Meloidogyne enterolobii, a Major Threat to Tomato Production: Current Status and Future Prospects for Its Management}, volume={11}, ISSN={["1664-462X"]}, DOI={10.3389/fpls.2020.606395}, abstractNote={The guava root-knot nematode, Meloidogyne enterolobii (Syn. M. mayaguensis), is an emerging pathogen to many crops in the world. This nematode can cause chlorosis, stunting, and reduce yields associated with the induction of many root galls on host plants. Recently, this pathogen has been considered as a global threat for tomato (Solanum lycopersicum L.) production due to the lack of known resistance in commercially accepted varieties and the aggressiveness of M. enterolobii. Both conventional morphological and molecular approaches have been used to identify M. enterolobii, an important first step in an integrated management. To combat root-knot nematodes, integrated disease management strategies such as crop rotation, field sanitation, biocontrol agents, fumigants, and resistant cultivars have been developed and successfully used in the past. However, the resistance in tomato varieties mediated by known Mi-genes does not control M. enterolobii. Here, we review the current knowledge on geographic distribution, host range, population biology, control measures, and proposed future strategies to improve M. enterolobii control in tomato.}, journal={FRONTIERS IN PLANT SCIENCE}, author={Philbrick, Ashley N. and Adhikari, Tika B. and Louws, Frank J. and Gorny, Adrienne M.}, year={2020}, month={Nov} }
 @article{acharya_ingram_oh_adhikari_dean_louws_2020, title={Opportunities and Challenges in Studies of Host-Pathogen Interactions and Management of Verticillium dahliae in Tomatoes}, volume={9}, url={https://doi.org/10.3390/plants9111622}, DOI={10.3390/plants9111622}, abstractNote={Tomatoes (Solanum lycopersicum L.) are a valuable horticultural crop that are grown and consumed worldwide. Optimal production is hindered by several factors, among which Verticillium dahliae, the cause of Verticillium wilt, is considered a major biological constraint in temperate production regions. V. dahliae is difficult to mitigate because it is a vascular pathogen, has a broad host range and worldwide distribution, and can persist in soil for years. Understanding pathogen virulence and genetic diversity, host resistance, and plant-pathogen interactions could ultimately inform the development of integrated strategies to manage the disease. In recent years, considerable research has focused on providing new insights into these processes, as well as the development and integration of environment-friendly management approaches. Here, we discuss the current knowledge on the race and population structure of V. dahliae, including pathogenicity factors, host genes, proteins, enzymes involved in defense, and the emergent management strategies and future research directions for managing Verticillium wilt in tomatoes.}, number={11}, journal={Plants}, publisher={MDPI AG}, author={Acharya, Bhupendra and Ingram, Thomas W. and Oh, YeonYee and Adhikari, Tika B. and Dean, Ralph A. and Louws, Frank J.}, year={2020}, month={Nov}, pages={1622} }
 @article{adhikari_gao_ingram_louws_2020, title={Pathogenomics Characterization of an Emerging Fungal Pathogen,Fusarium oxysporumf. sp.lycopersiciin Greenhouse Tomato Production Systems}, volume={11}, ISSN={["1664-302X"]}, DOI={10.3389/fmicb.2020.01995}, abstractNote={In recent years, greenhouse-grown tomato (Solanum lycopersicum) plants showing vascular wilt and yellowing symptoms have been observed between 2015 and 2018 in North Carolina (NC) and considered as an emerging threat to profitability. In total, 38 putative isolates were collected from symptomatic tomatoes in 12 grower greenhouses and characterized to infer pathogenic and genomic diversity, and mating-type (MAT) idiomorphs distribution. Morphology and polymerase chain reaction (PCR) markers confirmed that all isolates were Fusarium oxysporum f. sp. lycopersici (FOL) and most of them were race 3. Virulence analysis on four different tomato cultivars revealed that virulence among isolates, resistance in tomato cultivars, and the interaction between the isolates and cultivars differed significantly (P < 0.001). Cultivar ‘Happy Root’ (I-1, I-2, and I-3 genes for resistance) was highly resistant to FOL isolates tested. We sequenced and examined for the presence of 15 pathogenicity genes from different classes (Fmk1, Fow1, Ftf1, Orx1, Pda1, PelA, PelD, Pep1, Pep2, eIF-3, Rho1, Scd1, Snf1, Ste12, and Sge1), and 14 Secreted In Xylem (SIX) genes to use as genetic markers to identify and differentiate pathogenic isolates of FOL. Sequence data analysis showed that five pathogenicity genes, Fmk1, PelA, Rho1, Sge1, and Ste12 were present in all isolates while Fow1, Ftf1, Orx1, Peda1, Pep1, eIF-3, Scd1, and Snf1 genes were dispersed among isolates. Two genes, Pep2 and PelD, were absent in all isolates. Of the 14 SIX genes assessed, SIX1, SIX3, SIX5, SIX6, SIX7, SIX8, SIX12, and SIX14 were identified in most isolates while the remaining SIX genes varied among isolates. All isolates harbored one of the two mating-type (MAT-1 or MAT-2) idiomorphs, but not both. The SIX4 gene was present only in race 1 isolates. Diversity assessments based on sequences of the effector SIX3- and the translation elongation factor 1-α encoding genes SIX3 and tef1-α, respectively were the most informative to differentiate pathogenic races of FOL and resulted in race 1, forming a monophyletic clade while race 3 comprised multiple clades. Furthermore, phylogeny-based on SIX3- and tef1-α gene sequences showed that the predominant race 3 from greenhouse production systems significantly overlapped with previously designated race 3 isolates from various regions of the globe.}, journal={FRONTIERS IN MICROBIOLOGY}, author={Adhikari, Tika B. and Gao, Anne and Ingram, Thomas and Louws, Frank J.}, year={2020}, month={Aug} }
 @article{screening tomato breeding lines for bacterial wilt resistance in nc_2020, url={https://publons.com/wos-op/publon/51538717/}, journal={Hortscience}, year={2020} }
 @article{gottwald_luo_posny_riley_louws_2019, title={A probabilistic census-travel model to predict introduction sites of exotic plant, animal and human pathogens}, volume={374}, ISSN={["1471-2970"]}, url={http://dx.doi.org/10.1098/rstb.2018.0260}, DOI={10.1098/rstb.2018.0260}, abstractNote={
            International travel offers an extensive network for new and recurring human-mediated introductions of exotic infectious pathogens and biota, freeing geographical constraints. We present a predictive census-travel model that integrates international travel with endpoint census data and epidemiological characteristics to predict points of introduction. Population demographics, inbound and outbound travel patterns, and quantification of source strength by country are combined to estimate and rank risk of introduction at user-scalable land parcel areas (e.g. state, county, zip code, census tract, gridded landscapes (1 mi
            2
            , 5 km
            2
            , etc.)). This risk ranking by parcel can be used to develop pathogen surveillance programmes, and has been incorporated in multiple US state/federal surveillance protocols. The census-travel model is versatile and independent of pathosystems, and applies a risk algorithm to generate risk maps for plant, human and animal contagions at different spatial scales. An interactive, user-friendly interface is available online (https://epi-models.shinyapps.io/Census_Travel/) to provide ease-of-use for regulatory agencies for early detection of high-risk exotics. The interface allows users to parametrize and run the model without knowledge of background code and underpinning data.
          }, number={1776}, journal={PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES}, author={Gottwald, Tim and Luo, Weiqi and Posny, Drew and Riley, Tim and Louws, Frank}, year={2019}, month={Jul} }
 @article{suchoff_schultheis_gunter_hassell_louws_2019, title={Effect of rootstock and nitrogen fertilizer on growth and yield in watermelon}, volume={94}, ISSN={["2380-4084"]}, url={http://dx.doi.org/10.1080/14620316.2019.1624629}, DOI={10.1080/14620316.2019.1624629}, abstractNote={ABSTRACT Herbaceous grafting can be used to manage numerous soilborne pathogens in cucurbits. Rootstocks have been reported to increase the growth of the scion possibly due to more efficient use of nitrogen compared with non-grafted plants. The first objective of this study was to determine if the commercial rootstocks ‘Strongtosa’, ‘Carnivor’, or ‘Macis’ improve growth and production of the watermelon ‘Melody’ scion. The second objective was to determine whether these rootstocks have different nitrogen requirements in open-field production compared with non-grafted ‘Melody’. Field studies were conducted in 2013 and 2014 on the Sandhills Research Station in Jackson Springs, North Carolina. Nitrogen fertiliser was applied via drip irrigation at 0, 84, 126, 168, and 252 kg⋅ha−1. A linear relationship between nitrogen rate and rootstock cultivar existed; however, in all cases the non-grafted plants produced more than all grafted plants. Average fruit weight from the non-grafted plants was also higher than the grafted plants. Fruit from ‘Carnivor’- and ‘Strongtosa’-grafted plants had higher flesh firmness compared with non-grafted ‘Melody’. Our findings suggest that rootstocks do not increase yield or growth in the scion nor do they require different nitrogen application rates. However, some rootstocks do improve overall fruit quality.}, number={6}, journal={JOURNAL OF HORTICULTURAL SCIENCE & BIOTECHNOLOGY}, author={Suchoff, David H. and Schultheis, Jonathan R. and Gunter, Christopher C. and Hassell, Richard L. and Louws, Frank J.}, year={2019}, month={Nov}, pages={798–804} }
 @article{effector profile analysis of the tomato and pepper pathogens xanthomonas perforans and x. euvesicatoria_2019, url={https://publons.com/wos-op/publon/43810292/}, journal={Molecular Plant-Microbe Interactions}, year={2019} }
 @article{effector profiles of xanthomonas perforans and x. euvesicatoria provide insights into the evolution of host range and virulence in bls pathogens_2019, url={https://publons.com/wos-op/publon/35502815/}, journal={Phytopathology}, year={2019} }
 @article{adhikari_chacon_fernandez_louws_2019, title={First Report of Anthracnose Causing Both Crown and Fruit Rot of Strawberry by Colletotrichum siamense in North Carolina}, volume={5}, ISSN={0191-2917 1943-7692}, url={http://dx.doi.org/10.1094/pdis-02-19-0314-pdn}, DOI={10.1094/pdis-02-19-0314-pdn}, abstractNote={HomePlant DiseaseVol. 103, No. 7First Report of Anthracnose Causing Both Crown and Fruit Rot of Strawberry by Colletotrichum siamense in North Carolina PreviousNext DISEASE NOTESFirst Report of Anthracnose Causing Both Crown and Fruit Rot of Strawberry by Colletotrichum siamense in North CarolinaT. B. Adhikari, J. G. Chacon, G. E. Fernandez, and F. J. LouwsT. B. Adhikari†Corresponding author: T. B. Adhikari; E-mail Address: [email protected]http://orcid.org/0000-0001-7118-6875Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695Search for more papers by this author, J. G. ChaconDepartment of Horticultural Science, North Carolina State University, Raleigh, NC 27695Search for more papers by this author, G. E. FernandezDepartment of Horticultural Science, North Carolina State University, Raleigh, NC 27695Search for more papers by this author, and F. J. LouwsDepartment of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695Search for more papers by this authorAffiliationsAuthors and Affiliations T. B. Adhikari1 † J. G. Chacon2 G. E. Fernandez2 F. J. Louws1 2 1Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695 2Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695 Published Online:10 May 2019https://doi.org/10.1094/PDIS-02-19-0314-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Anthracnose fruit rot and anthracnose crown rot of strawberries (Fragaria × ananassa Duch.), caused by Colletotrichum spp., have been mainly associated with the C. acutatum complex (Baroncelli et al. 2015; Damm et al. 2012) and the C. gloeosporioides complex (Weir et al. 2012), respectively. In September 2017, typical symptoms of anthracnose were observed on strawberry plants in a propagation greenhouse in North Carolina, U.S.A. Symptoms that appeared were crown rotting, wilting, and stunting. Small pieces (2 mm2) of necrotic tissue were cut with a sterile scalpel from the crown lesion. Approximately 15% of the plants showed such typical symptoms. The diseased segment was surface sterilized with 70% ethanol for 30 s and placed on acidified potato dextrose agar (APDA). Hyphal tips from colonies emerging from the edge of the tissue were transferred onto fresh APDA Petri plates and incubated at 25°C. Morphological characteristics after 7 days of incubation showed light-gray to whitish aerial mycelium. Conidia were hyaline, aseptate, fusiform with obtuse ends, cylindrical, 13.2 to 17.5 µm long, and 4.9 to 7.5 µm wide. These characteristics of conidia were matched with some species belonging to the C. gloeosporioides complex including C. siamense (Weir et al. 2012). For accurate identification, genomic DNA of isolate 28244 was extracted and amplified with partial sequences of actin (ACT), chitin synthase (CHS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ribosomal internal transcribed spacer (ITS), and manganese-superoxide dismutase (SOD2) primer sets (Weir et al. 2012). Sequencing of the purified polymerase chain reaction products was performed at the Genomic Sciences Laboratory, North Carolina State University, Raleigh, NC (White et al. 1990). Sequences of the amplified regions of isolate 28244 were deposited to GenBank (accession nos. MH722310 to MH722314). Additionally, sequences of 22 Colletotrichum species within the C. gloeosporioides complex (Weir et al. 2012) were retrieved from GenBank. Jukes–Cantor neighbor-joining trees inferred from the concatenated sequences (ACT, CHS, GAPDH, ITS, and SOD2) placed isolate 28244 from North Carolina within the same cluster of C. siamense including isolate BRSP09 from Bangladesh (Gupta et al. 2018). These sequences were compared with the GenBank database using BLASTn and revealed a high percentage of similarity (>99%). To confirm pathogenicity of the fungus, Koch’s postulates were performed by three methods. Three-month-old strawberry plants of cultivar ‘Camarosa’ were either spray inoculated on leaves with a conidial suspension (106 conidia/ml) or injected (10 μl) into the crown of each plant. Ten plants inoculated with distilled water served as controls. Plants were covered with plastic bags for 48 h and placed in the greenhouse at 28°C. Leaf and crown rot symptoms were monitored weekly after inoculation. No symptoms or spores developed on leaves, which was also confirmed by a paraquat assay after the first 3 weeks. However, dark brown necrotic lesions were observed on the crowns 4 weeks after inoculation. The fungus was reisolated from the inoculated crown tissues. In another experiment, 10 immature (half-green and half-yellow) strawberry fruit (cv. ‘Chandler’) were surface sterilized with 70% ethanol and then 0.5% sodium hypochlorite for 30 s and rinsed with sterile distilled water three times. Fruit was injected with 10 μl of conidial suspension (106 conidia/ml) and placed in a plastic crisper container. Sterile distilled water–inoculated fruits served as controls. Fruits in the containers were incubated at 25°C in the dark. All experiments were conducted twice. Fruit rot symptoms were observed on fruits 3 days after inoculation, and the control fruits remained asymptomatic. Within the C. gloeosporioides species complex, C. aenigma, C. fructicola, C. siamense, and C. theobromicola were previously reported on strawberries (Baroncelli et al. 2015; Weir et al. 2012). More recently, C. siamense has been reported to cause crown rot of strawberry in Bangladesh (Gupta et al. 2018) and fruit rot on strawberry in Brazil (Capobiango et al. 2016). To our best knowledge, this is the first report of anthracnose causing both crown and fruit rot of strawberry by C. siamense, one of the species within the C. gloeosporioides complex, in North Carolina. This disease can seriously affect strawberry fruit quality and yield and is capable of producing resistance to Fungicide Resistance Action Committee code 11 fungicides (Hu et al. 2015); thus, effective disease management strategies should be investigated and implemented.The author(s) declare no conflict of interest.References:Baroncelli, R. et al. 2015. PLoS One 10:e0129140. https://doi.org/10.1371/journal.pone.0129140 Crossref, ISI, Google ScholarCapobiango, N. P. et al. 2016. Plant Dis. 100:859. https://doi.org/10.1094/PDIS-10-15-1121-PDN Link, ISI, Google ScholarDamm, U. et al. 2012. Stud. Mycol. 73:37. https://doi.org/10.3114/sim0010 Crossref, ISI, Google ScholarGupta, D. R. et al. 2018. Plant Dis. 103:580. https://doi.org/10.1094/PDIS-08-18-1461-PDN Link, ISI, Google ScholarHu, et al. 2015. Plant Dis. 99:806. https://doi.org/10.1094/PDIS-10-14-1077-RE Link, ISI, Google ScholarWeir, B. S., et al. 2012. Stud. Mycol. 73:115. https://doi.org/10.3114/sim0011 Crossref, ISI, Google ScholarWhite, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. Crossref, Google ScholarThe author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 103, No. 7 July 2019SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionApple cultivar Joya Cripps Red lesions caused by Colletotrichum fructicola (Nodet et al.). Photo credit: P. Nodet. Symptoms of Lotus powdery mildew caused by Erysiphe takamatsui (Zhou et al.). Photo credit: C. Liang. Symptoms of tar spot (Phyllachora maydis) on maize leaves (Dalla Lana et al.). Photo credit: F. Dalla Lana. Metrics Article History Issue Date: 20 Jun 2019Published: 10 May 2019First Look: 4 Mar 2019Accepted: 13 Feb 2019 Pages: 1775-1775 Information© 2019 The American Phytopathological SocietyKeywordsfungismall fruitsetiologyThe author(s) declare no conflict of interest.Cited byComparative characterization and expression analysis revealed cinnamyl alcohol dehydrogenase genes differentially responding to Colletotrichum fructicola in woodland and cultivated strawberriesJournal of Berry Research, Vol. 17Different responses to elevated temperature in the representative strains of strawberry pathogenic Colletotrichum spp.from eastern China9 December 2022 | Mycological Progress, Vol. 22, No. 1Identification and Observation of Infection Processes of Colletotrichum Species Associated with Pearl Plum Anthracnose in Guangxi, ChinaRong Huang, Qing Gui, Yujie Zhang, Wenxiu Sun, Lihua Tang, Suiping Huang, Tangxun Guo, Qili Li, Jianyou Mo, Huiye Huang, Mingzhong Fan, Zongbin Zhang, and Tom Hsiang20 November 2022 | Plant Disease, Vol. 106, No. 12Colletotrichum species pathogenic to strawberry: discovery history, global diversity, prevalence in China, and the host range of top two species16 November 2022 | Phytopathology Research, Vol. 4, No. 1Comparative Analysis of the Microbial Community Structures Between Healthy and Anthracnose-Infected Strawberry Rhizosphere Soils Using Illumina Sequencing Technology in Yunnan Province, Southwest of China16 May 2022 | Frontiers in Microbiology, Vol. 13Characterization of Colletotrichum siamense causing crown rot of strawberry in Jingzhou, Hubei Province18 August 2021 | Notulae Botanicae Horti Agrobotanici Cluj-Napoca, Vol. 49, No. 3Resistance to Azoxystrobin and Thiophanate-Methyl Is Widespread in Colletotrichum spp. Isolates From the Mid-Atlantic Strawberry FieldsQiuchen Luo, Anita Schoeneberg, and Mengjun Hu15 September 2021 | Plant Disease, Vol. 105, No. 8Diversity and Cross-Infection Potential of Colletotrichum Causing Fruit Rots in Mixed-Fruit Orchards in KentuckyMadison J. Eaton, Shanice Edwards, Harrison A. Inocencio, Franklin J. Machado, Etta M. Nuckles, Mark Farman, Nicole A. Gauthier, and Lisa J. Vaillancourt26 February 2021 | Plant Disease, Vol. 105, No. 4Diversity and pathogenicity of Colletotrichum species causing strawberry anthracnose in Taiwan and description of a new species, Colletotrichum miaoliense sp. nov.4 September 2020 | Scientific Reports, Vol. 10, No. 1}, journal={Plant Disease}, publisher={Scientific Societies}, author={Adhikari, T. B. and Chacon, J. G. and Fernandez, G. E. and Louws, F. J.}, year={2019}, month={May}, pages={PDIS-02–19-0314} }
 @article{planas-marquès_kressin_kashyap_panthee_louws_coll_valls_2019, title={Four bottlenecks restrict colonization and invasion by the pathogen Ralstonia solanacearum in resistant tomato}, volume={71}, ISSN={0022-0957 1460-2431}, url={http://dx.doi.org/10.1093/jxb/erz562}, DOI={10.1093/jxb/erz562}, abstractNote={Abstract}, number={6}, journal={Journal of Experimental Botany}, publisher={Oxford University Press (OUP)}, author={Planas-Marquès, Marc and Kressin, Jonathan P and Kashyap, Anurag and Panthee, Dilip R and Louws, Frank J and Coll, Nuria S and Valls, Marc}, editor={Bozhkov, PeterEditor}, year={2019}, month={Dec}, pages={2157–2171} }
 @article{adhikari_knaus_grünwald_halterman_louws_2019, title={Inference of Population Genetic Structure and High Linkage Disequilibrium Among Alternaria spp. Collected from Tomato and Potato Using Genotyping by Sequencing}, volume={11}, url={https://www.biorxiv.org/content/10.1101/827790v1}, DOI={10.1101/827790}, abstractNote={ABSTRACT}, journal={PLoS ONE}, publisher={Cold Spring Harbor Laboratory}, author={Adhikari, Tika B. and Knaus, Brian J. and Grünwald, Niklaus J. and Halterman, Dennis and Louws, Frank J.}, year={2019}, month={Nov} }
 @article{jacobs_adhikari_pattison_yencho_fernandez_louws_2019, title={Inheritance of Resistance to Colletotrichum gloeosporioides and C. acutatum in Strawberry}, volume={109}, ISSN={0031-949X 1943-7684}, url={http://dx.doi.org/10.1094/PHYTO-08-18-0283-R}, DOI={10.1094/PHYTO-08-18-0283-R}, abstractNote={ Information on the inheritance of resistance to Colletotrichum gloeosporioides and C. acutatum hemibiotrophic infections (HBI) in strawberry leaf tissue and the genetic control of anthracnose crown rot (ACR) in crown tissue are relatively unknown. Six parental genotypes were crossed in a half-diallel mating design to generate 15 full-sib families. HBI and ACR experiments were conducted concurrently. Both seedlings and parental clones were inoculated with 1 × 106 conidia/ml of C. gloeosporioides or C. acutatum. Percent sporulating leaf area, wilt symptoms, and relative area under the disease progress curve were calculated to characterize resistance among genotypes and full-sib families. Low dominance/additive variance ratios for C. acutatum HBI (0.13) and C. gloeosporioides ACR (0.20) were observed, indicating additive genetic control of resistance to these traits. Heritability estimates were low for C. acutatum HBI (0.25) and C. gloeosporioides HBI (0.16) but moderate for C. gloeosporioides ACR (0.61). A high genetic correlation (rA = 0.98) between resistance to C. acutatum HBI and C. gloeosporioides HBI was observed, suggesting that resistance to these two Colletotrichum spp. may be controlled by common genes in strawberry leaf tissue. In contrast, negative genetic correlations between ACR and both HBI traits (rA = −0.85 and −0.61) suggest that resistance in crown tissue is inherited independently of resistance in leaf tissue in the populations tested. Overall, these findings provide valuable insight into the genetic basis of resistance, and the evaluation and deployment of resistance to HBIs and ACR in strawberry breeding programs. }, number={3}, journal={Phytopathology}, publisher={Scientific Societies}, author={Jacobs, Raymond L. and Adhikari, Tika B. and Pattison, Jeremy and Yencho, G. Craig and Fernandez, Gina E. and Louws, Frank J.}, year={2019}, month={Mar}, pages={428–435} }
 @article{adhikari_adhikari_timilsina_meadows_jones_panthee_louws_2019, title={Phenotypic and Genetic Diversity of Xanthomonas perforans Populations from Tomato in North Carolina}, volume={109}, ISSN={["1943-7684"]}, url={http://dx.doi.org/10.1094/phyto-01-19-0019-r}, DOI={10.1094/PHYTO-01-19-0019-R}, abstractNote={Bacterial spot caused by Xanthomonas spp. is one of the most devastating diseases of tomato in North Carolina (NC). In total, 290 strains of Xanthomonas spp. from tomato in NC collected over 2 years (2015 and 2016) were analyzed for phenotypic and genetic diversity. In vitro copper and streptomycin sensitivity assays revealed that >95% (n = 290) of the strains were copper tolerant in both years, whereas 25% (n = 127) and 46% (n = 163) were streptomycin tolerant in 2016 and 2015, respectively. Using BOX repetitive element PCR assay, fingerprint patterns showed four haplotypes (H1, H2, H3, and H4) among the strains analyzed. The multiplex real-time quantitative PCR on a subset of representative strains (n = 45) targeting the highly conserved hrcN gene identified Xanthomonas strains from tomato in NC that belonged to X. perforans. Race profiling of the representative strains (n = 45) on tomato and pepper differentials confirmed that ∼9 and 91% of strains are tomato races T3 and T4, respectively. Additionally, PCR assays and sequence alignments confirmed that the copL, copA, copB (copLAB copper tolerance gene cluster), and avrXv4 genes are present in the strains analyzed. Phylogenetic and comparative sequence analyses of six genomic regions (elongation factor G [fusA], glyceraldehyde-3-phosphate dehydrogenase A [gapA], citrate synthase [gltA], gyrase subunit B [gyrB], ABC transporter sugar permease [lacF], and GTP binding protein [lepA]) suggested that 13 and 74% of X. perforans strains from NC were genetically similar to races T3 and T4 from Florida, respectively. Our results provide insights that bacterial spot management practices in tomato should focus on deploying resistance genes to combat emerging pathogenic races of X. perforans and overcome the challenges currently posed by intense use of copper-based bactericides.}, number={9}, journal={PHYTOPATHOLOGY}, author={Adhikari, Pragya and Adhikari, Tika B. and Timilsina, Sujan and Meadows, Inga and Jones, Jeffrey B. and Panthee, Dilip R. and Louws, Frank J.}, year={2019}, month={Sep}, pages={1533–1543} }
 @article{resistance to non-race 1 verticillium dahliae in tomatoes suppresses necrosis and chlorosis symptoms in infected plants_2019, url={https://publons.com/wos-op/publon/56007333/}, journal={Phytopathology}, year={2019} }
 @article{structural restriction to ralstonia solanacearum colonization and invasion in resistant tomato varieties_2019, url={https://publons.com/wos-op/publon/34816003/}, journal={Molecular Plant-Microbe Interactions}, year={2019} }
 @article{suchoff_gunter_schultheis_hassell_louws_2019, title={The effect of grafting on nitrogen use in determinate field-grown tomatoes}, volume={94}, ISSN={["2380-4084"]}, url={http://dx.doi.org/10.1080/14620316.2018.1450645}, DOI={10.1080/14620316.2018.1450645}, abstractNote={ABSTRACTGrafting tomato (Solanum lycopersicum L.) onto disease resistant rootstocks has grown in use in North America over the past two decades. Rootstocks have traditionally been bred and used for...}, number={1}, journal={JOURNAL OF HORTICULTURAL SCIENCE & BIOTECHNOLOGY}, author={Suchoff, David H. and Gunter, Christopher C. and Schultheis, Jonathan R. and Hassell, Richard L. and Louws, Frank J.}, year={2019}, month={Jan}, pages={102–109} }
 @article{suchoff_louws_gunter_2019, title={Yield and Disease Resistance for Three Bacterial Wilt-resistant Tomato Rootstocks}, volume={29}, ISSN={["1943-7714"]}, url={http://dx.doi.org/10.21273/horttech04318-19}, DOI={10.21273/HORTTECH04318-19}, abstractNote={Interest and use of grafted tomato (Solanum lycopersicum) in the United States continues to grow. Pioneered in Asia, herbaceous grafting is a commonly used cultural practice to manage many soilborne pathogens. Bacterial wilt (BW), caused by the pathogen Ralstonia solanacearum, is an aggressive soilborne pathogen that affects tomato grown in the southeastern United States. Traditional fumigation methods have limited effectiveness in the management of this pathogen. The present study was conducted to compare the bacterial wilt resistance of three commercially available tomato rootstocks, which are purported to be resistant to bacterial wilt: ‘Cheong Gang’, ‘RST-04-106-T’, and ‘Shield’. The determinate hybrid tomato ‘Red Mountain’, which is susceptible to bacterial wilt, was used as the scion and nongrafted control. Three locations were used over 2 years in North Carolina: an on-farm site with a history of bacterial wilt and two North Carolina Department of Agriculture Research Stations with no recent history of bacterial wilt. No disease symptoms were observed in any of the three grafted treatments, whereas the nongrafted controls showed between 30% and 80% disease incidence at the on-farm location. The resultant rootstock-imparted resistance improved marketable yields by between 88% and 125% compared with the nongrafted plants. When grown in locations lacking BW there were no yield benefits to grafting with any of the three rootstocks.}, number={3}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Suchoff, David H. and Louws, Frank J. and Gunter, Christopher C.}, year={2019}, month={Jun}, pages={330–337} }
 @article{bertucci_suchoff_jennings_monks_gunter_schultheis_louws_2018, title={Comparison of Root System Morphology of Cucurbit Rootstocks for Use in Watermelon Grafting}, volume={28}, ISSN={["1943-7714"]}, url={https://publons.com/wos-op/publon/39930266/}, DOI={10.21273/HORTTECH04098-18}, abstractNote={Grafting of watermelon (Citrullus lanatus) is an established production practice that provides resistance to soilborne diseases or tolerance to abiotic stresses. Watermelon may be grafted on several cucurbit species (interspecific grafting); however, little research exists to describe root systems of these diverse rootstocks. A greenhouse study was conducted to compare root system morphology of nine commercially available cucurbit rootstocks, representing four species: pumpkin (Cucurbita maxima), squash (Cucurbita pepo), bottle gourd (Lagenaria siceraria), and an interspecific hybrid squash (C. maxima × C. moschata). Rootstocks were grafted with a triploid watermelon scion (‘Exclamation’), and root systems were compared with nongrafted (NG) and self-grafted (SG) ‘Exclamation’. Plants were harvested destructively at 1, 2, and 3 weeks after transplant (WAT), and data were collected on scion dry weight, total root length (TRL), average root diameter, root surface area, root:shoot dry-weight ratio, root diameter class proportions, and specific root length. For all response variables, the main effect of rootstock and rootstock species was significant (P < 0.05). The main effect of harvest was significant (P < 0.05) for all response variables, with the exception of TRL proportion in diameter class 2. ‘Ferro’ rootstock produced the largest TRL and root surface area, with observed values 122% and 120% greater than the smallest root system (‘Exclamation’ SG), respectively. Among rootstock species, pumpkin produced the largest TRL and root surface area, with observed values 100% and 82% greater than those of watermelon, respectively. These results demonstrate that substantial differences exist during the initial 3 WAT in root system morphology of rootstocks and rootstock species available for watermelon grafting and that morphologic differences of root systems can be characterized using image analysis.}, number={5}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Bertucci, Matthew B. and Suchoff, David H. and Jennings, Katherine M. and Monks, David W. and Gunter, Christopher C. and Schultheis, Jonathan R. and Louws, Frank J.}, year={2018}, month={Oct}, pages={629–636} }
 @article{bertucci_jennings_monks_schultheis_louws_jordan_brownie_2018, title={Critical Period for Weed Control in Grafted and Nongrafted Watermelon Grown in Plasticulture}, volume={67}, ISSN={1550-2759}, url={http://dx.doi.org/10.1017/WSC.2018.76}, DOI={10.1017/wsc.2018.76}, abstractNote={Abstract}, number={2}, journal={Weed Science}, publisher={Cambridge University Press (CUP)}, author={Bertucci, Matthew B. and Jennings, Katherine M. and Monks, David W. and Schultheis, Jonathan R. and Louws, Frank J. and Jordan, David L. and Brownie, Cavell}, year={2018}, month={Nov}, pages={221–228} }
 @article{bertucci_jennings_monks_schultheis_perkins-veazie_louws_jordan_2018, title={Early Season Growth, Yield, and Fruit Quality of Standard and Mini Watermelon Grafted onto Several Commercially Available Cucurbit Rootstocks}, volume={28}, ISSN={["1943-7714"]}, DOI={10.21273/HORTTECH04051-18}, abstractNote={Grafting watermelon (Citrullus lanatus) is a common practice in many parts of the world and has recently received increased interest in the United States. The present study was designed to evaluate early season growth, yield, and fruit quality of watermelon in response to grafting and in the absence of known disease pressure in a fumigated system. Field experiments were conducted using standard and mini watermelons (cv. Exclamation and Extazy, respectively) grafted onto 20 commercially available cucurbit rootstocks representing four species: giant pumpkin (Cucurbita maxima), summer squash (Cucurbita pepo), bottle gourd (Lagenaria siceraria), and interspecific hybrid squash [ISH (C. maxima × Cucurbita moschata)]. Nongrafted ‘Exclamation’ and ‘Extazy’ were included as controls. To determine early season growth, leaf area was measured at 1, 2, and 3 weeks after transplant (WAT). At 1 WAT, nongrafted ‘Exclamation’ produced the smallest leaf area; however, at 3 WAT, nongrafted ‘Exclamation’ produced the largest leaf area in 2015, and no differences were observed in 2016. Leaf area was very similar among rootstocks in the ‘Extazy’ study, with minimal differences observed. Marketable yield included fruit weighing ≥9 and ≥3 lb for ‘Exclamation’ and ‘Extazy’, respectively. In the ‘Exclamation’ study, highest marketable yields were observed in nongrafted ‘Exclamation’, and ‘Exclamation’ grafted to ‘Pelops’, ‘TZ148’, and ‘Coloso’, and lowest marketable yields were observed when using ‘Marvel’ and ‘Kazako’ rootstocks, which produced 47% and 32% of nongrafted ‘Exclamation’ yield, respectively. In the ‘Extazy’ study, the highest marketable yield was observed in nongrafted ‘Extazy’, and ‘Kazako’ produced the lowest yields (48% of nongrafted ‘Extazy’). Fruit quality was determined by measuring fruit acidity (pH), soluble solids concentration (SSC), lycopene content, and flesh firmness from a sample of two fruit from each plot from the initial two harvests of each year. Across both studies, rootstock had no effect on SSC or lycopene content. As reported in previous studies, flesh firmness was increased as a result of grafting, and nongrafted ‘Exclamation’ and ‘Extazy’ had the lowest flesh firmness among standard and mini watermelons, respectively. The present study evaluated two scions with a selection of 20 cucurbit rootstocks and observed no benefits in early season growth, yield, or phytonutrient content. Only three of 20 rootstocks in each study produced marketable yields similar to the nongrafted treatments, and no grafted treatment produced higher yields than nongrafted ‘Exclamation’ or ‘Extazy’. Because grafted seedlings have an associated increase in cost and do not produce increased yields, grafting in these optimized farming systems and using fumigated soils does not offer an advantage in the absence of soilborne pathogens or other stressors that interfere with watermelon production.}, number={4}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Bertucci, Matthew B. and Jennings, Katherine M. and Monks, David W. and Schultheis, Jonathan R. and Perkins-Veazie, Penelope and Louws, Frank J. and Jordan, David L.}, year={2018}, month={Aug}, pages={459–469} }
 @article{bertucci_jennings_monks_jordan_schultheis_louws_waldschmidt_2018, title={Effect of Bicyclopyrone on Triploid Watermelon in Plasticulture}, volume={32}, ISSN={0890-037X 1550-2740}, url={http://dx.doi.org/10.1017/WET.2018.36}, DOI={10.1017/WET.2018.36}, abstractNote={Abstract}, number={4}, journal={Weed Technology}, publisher={Cambridge University Press (CUP)}, author={Bertucci, Matthew B. and Jennings, Katherine M. and Monks, David W. and Jordan, David L. and Schultheis, Jonathan R. and Louws, Frank J. and Waldschmidt, Matthew D.}, year={2018}, month={Jun}, pages={439–443} }
 @article{louws_2018, title={Evaluation of biopesticides and biorationals on bacterial canker and bacterial spot disease levels in tomato fresh-market production in North Carolina}, volume={1207}, ISSN={["2406-6168"]}, url={https://publons.com/wos-op/publon/42361133/}, DOI={10.17660/ActaHortic.2018.1207.33}, number={1207}, journal={V INTERNATIONAL SYMPOSIUM ON TOMATO DISEASES: PERSPECTIVES AND FUTURE DIRECTIONS IN TOMATO PROTECTION}, publisher={International Society for Horticultural Science (ISHS)}, author={Louws, F. J.}, year={2018}, pages={241–247} }
 @article{grafted tomato shoot and root responses to drying soils_2018, url={https://publons.com/wos-op/publon/56007342/}, journal={Hortscience}, year={2018} }
 @article{suchoff_perkins-veazie_sederoff_schultheis_kleinhenz_louws_gunter_2018, title={Grafting the Indeterminate Tomato Cultivar Moneymaker onto Multifort Rootstock Improves Cold Tolerance}, volume={53}, ISSN={["2327-9834"]}, url={https://publons.com/wos-op/publon/38620980/}, DOI={10.21273/HORTSCI13311-18}, abstractNote={Tomato (Solanum lycopersicum L.) is a warm-season, cold-sensitive crop that shows slower growth and development at temperatures below 18 °C. Improving suboptimal temperature tolerance would allow earlier planting of field-grown tomato and a reduction in energy inputs for heating greenhouses. Grafting tomato onto high-altitude Solanum habrochaites (S. Knapp and D.M. Spooner) accessions has proven effective at improving scion suboptimal temperature tolerance in limited experiments. This study was conducted to determine whether commercially available tomato rootstocks with differing parental backgrounds and root system morphologies can improve the tolerance of scion plants to suboptimal temperature. Two controlled environment growth chambers were used and maintained at either optimal (25 °C day/20 °C night) or suboptimal (15 °C day/15 °C night) temperatures. The cold-sensitive tomato cultivar Moneymaker was used as the nongrafted and self-grafted control as well as scion grafted on ‘Multifort’ (S. lycopersicum × S. habrochaites), ‘Shield’ (S. lycopersicum), and S. habrochaites LA1777 rootstocks. Plants were grown for 10 days in 3.8 L plastic containers filled with a mixture of calcined clay and sand. ‘Multifort’ rootstock significantly reduced the amount of cold-induced stress as observed by larger leaf area and higher levels of CO2 assimilation and photosystem II quantum efficiency. ‘Multifort’ had significantly longer roots, having 42% to 56% more fine root (diameter less than 0.5 mm) length compared with the other nongrafted and grafted treatments. Leaf starch concentration was significantly lower in ‘Multifort’-grafted plants at suboptimal temperatures compared with the self-grafted and nongrafted controls and the ‘Shield’-grafted plants at the same temperature. The ability for ‘Multifort’ to maintain root growth at suboptimal temperatures may improve root system sink strength, thereby promoting movement of photosynthate from leaf to root even under cold conditions. This work demonstrates that a commercially available rootstock can be used to improve suboptimal temperature tolerance in cold-sensitive ‘Moneymaker’ scions.}, number={11}, journal={HORTSCIENCE}, author={Suchoff, David H. and Perkins-Veazie, Penelope and Sederoff, Heike W. and Schultheis, Jonathan R. and Kleinhenz, Matthew D. and Louws, Frank J. and Gunter, Christopher C.}, year={2018}, month={Nov}, pages={1610–1617} }
 @article{improving tomato cold tolerance through grafting_2018, url={https://publons.com/wos-op/publon/38620984/}, journal={Hortscience}, year={2018} }
 @article{louws_suchoff_kressin_panthee_driver_gunter_2018, title={Integrating grafting and emerging products to manage soilborne diseases of tomato}, volume={1207}, ISSN={0567-7572 2406-6168}, url={http://dx.doi.org/10.17660/actahortic.2018.1207.34}, DOI={10.17660/ActaHortic.2018.1207.34}, abstractNote={Major soilborne diseases in North Carolina and surrounding states include fusarium wilt (FW) (causal agent Fusarium oxysporum f. sp. lycopersici; all three races), verticillium wilt (VW) (Verticillium dahliae; two races), southern stem blight (SSB) (Sclerotium rolfsii), root-knot nematodes (RKN) (primarily Meloidogyne incognita) and bacterial wilt (BW) (Ralstonia solanacearum race 1), distributed across the subtropical to temperate ecosystems in the state. FW, VW, SSB, and RKN can be well managed using standard fumigants. Alternative management practices are needed in production systems where fumigants are not used or effective, and/or where heirloom tomato cultivars are grown. We are involved in a USA multi-state program to determine the viability of grafting in open-field production systems. Previously published work showed the utility of grafting to manage FW, SSB, RKN, and BW. In complementary work to manage BW, a replicated on-farm field trial demonstrates that fumigants such as Paladin (79% dimethyl disulfide + 21% chloropicrin) and PicClor60 (60% chloropicrin + 40% 1,3-dichloropropene) allow up to 80% plant death, similar to incidence in non-fumigated plots, whereas grafting to resistant rootstock (Seminis 'Cheong Gang') confers 100% control in non-fumigated plots. Another on-farm randomized complete block design experiment demonstrated that three commercially available rootstocks conferred 100% plant stand, whereas non-grafted plants had 80% plant death using a round tomato scion ('Red Mountain') or 15% plant death using a roma tomato ('Picus'). Grafted plants show economic viability in North Carolina, and additional work is needed to optimize this tool in diverse production systems.}, number={1207}, journal={Acta Horticulturae}, publisher={International Society for Horticultural Science (ISHS)}, author={Louws, F.J. and Suchoff, D. and Kressin, J. and Panthee, D. and Driver, J. and Gunter, C.}, year={2018}, month={Jul}, pages={249–254} }
 @article{bertucci_jennings_monks_schultheis_louws_jordan_2018, title={Interference of Palmer amaranth (Amaranthus palmeri) Density in Grafted and Nongrafted Watermelon}, volume={67}, ISSN={1550-2759}, url={http://dx.doi.org/10.1017/WSC.2018.77}, DOI={10.1017/wsc.2018.77}, abstractNote={Abstract}, number={2}, journal={Weed Science}, publisher={Cambridge University Press (CUP)}, author={Bertucci, Matthew B. and Jennings, Katherine M. and Monks, David W. and Schultheis, Jonathan R. and Louws, Frank J. and Jordan, David L.}, year={2018}, month={Dec}, pages={229–238} }
 @article{new approaches to detection: canine surveillance of high risk pathogens_2018, url={https://publons.com/wos-op/publon/56007343/}, journal={Phytopathology}, year={2018} }
 @article{optimizing genetics to manage verticillium wilt in tomatoes through traditional breeding and grafting: an elusive challenge_2018, url={https://publons.com/wos-op/publon/56007337/}, journal={Phytopathology}, year={2018} }
 @article{suchoff_gunter_schultheis_kleinhenz_louws_2018, title={Rootstock Effect on Grafted Tomato Transplant Shoot and Root Responses to Drying Soils}, volume={53}, ISSN={["2327-9834"]}, url={https://publons.com/wos-op/publon/45897406/}, DOI={10.21273/HORTSCI13215-18}, abstractNote={Improvement of crop water use is imperative. Plants’ responses to limited water can dictate their ability to better use available resources and avoid prolonged and severe stress. The following study was conducted to determine how tomato (Solanum lycopersicum) rootstocks with different root system morphologies respond to drying soils. Plants were grown in pots containing an inorganic substrate composed of calcined clay and sand in a greenhouse on North Carolina State University’s campus. The heirloom tomato cultivar Cherokee Purple was used as the scion for ‘Beaufort’ and ‘Shield’ rootstocks as well as the self-grafted control. These rootstocks were assigned either normal or reduced irrigation treatments. Plants grown under the normal irrigation schedule were weighed and watered daily to maintain container capacity for one week. Those receiving reduced irrigation had all water withheld for one week, at which point strong midday wilting became evident. Shoot physiological and morphological data as well as root morphological data were collected at the end of the study. A constitutive positive increase on relative water content, leaf area, stomatal conductance (gS), and net CO2 assimilation rate was observed with scions grafted on ‘Beaufort’. In addition, this rootstock had a significantly longer total root system (118.6 m) compared with ‘Shield’ (94.9 m) and the self-grafted control (104.2 m). Furthermore, 76.4% of the total root length observed in ‘Beaufort’ was composed of very thin diameter roots ( <0.5 mm), which was higher than ‘Shield’ (73.67%) and the self-grafted control (69.07%). The only significant rootstock  irrigation interaction observed was for effective quantum yield of photosystem II (φPSII). At normal irrigation there were no differences among the rootstock treatments; however, at reduced irrigation ‘Beaufort’ had significantly higher φPSII than both ‘Shield’ and the self-grafted control. These results may explain some of the improved production and water use efficiency observed in field trials using ‘Beaufort’ rootstock, and data secured may allow for better screening of rootstocks for improved water use efficiency in the future.}, number={11}, journal={HORTSCIENCE}, publisher={American Society for Horticultural Science}, author={Suchoff, David H. and Gunter, Christopher C. and Schultheis, Jonathan R. and Kleinhenz, Matthew D. and Louws, Frank J.}, year={2018}, month={Nov}, pages={1586–1592} }
 @article{suchoff_schultheis_kleinhenz_louws_gunter_2018, title={Rootstock Improves High-tunnel Tomato Water Use Efficiency}, volume={28}, ISSN={["1943-7714"]}, DOI={10.21273/horttech04015-18}, abstractNote={The following study was conducted to address water use efficiency in grafted tomato (Solanum lycopersicum) in an on-farm environment. The commercial rootstock cultivars Beaufort (BE) and Shield (S) were chosen as these two have different root system morphologies that may benefit water use efficiency. The heirloom cultivar Cherokee Purple (CP) was grafted onto both rootstocks and used as the nongrafted control. The study was conducted in 2016 and 2017 on a 5-acre vegetable and cut flower farm in North Carolina’s Piedmont region. Plants were grown under protected, high-tunnel culture where they received either 100% (3 hours every other day) or 50% (1.5 hours every other day) of the grower’s normal irrigation regime. At 50% irrigation, ‘Beaufort’-grafted plants yielded significantly more than nongrafted ‘Cherokee Purple’ and ‘Shield’-grafted plants. Furthermore, ‘Beaufort’-grafted plants at 50% irrigation yielded more than nongrafted ‘Cherokee Purple’ receiving the 100% irrigation treatment. The ‘Beaufort’-grafted plants significantly improved irrigation water use efficiency (iWUE) at the 50% irrigation treatment compared with the other graft treatments. Yield and iWUE of ‘Shield’-grafted plants were comparable with the nongrafted ‘Cherokee Purple’ at both irrigation treatments. Regardless of irrigation treatment, grafting onto ‘Beaufort’ improved the quality of total fruit harvested. An economic assessment was conducted to determine the feasibility of using grafted plants in conditions lacking significant disease pressure. Purchasing grafted transplants would increase the initial investment by $5227.2 per acre. However, the increased yield obtained when using ‘Beaufort’ rootstock at 50% irrigation increased net revenue by $35,900.41 per acre compared with nongrafted ‘Cherokee Purple’ receiving 100% irrigation, amounting to a 44.6% increase in net revenue while saving ≈383,242 gal/acre of water per growing season. These results indicate that growers can select rootstocks to better manage water use in an environmentally friendly manner without limiting economic gains.}, number={3}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Suchoff, David H. and Schultheis, Jonathan R. and Kleinhenz, Matthew D. and Louws, Frank J. and Gunter, Christopher C.}, year={2018}, month={Jun}, pages={344–353} }
 @article{thirst quenching: improving tomato water use efficiency through grafting_2018, url={https://publons.com/wos-op/publon/56007338/}, journal={Hortscience}, year={2018} }
 @article{chaudhari_jennings_monks_jordan_gunter_louws_2017, title={Absorption, Translocation, and Metabolism of 14C-Halosulfuron in Grafted Eggplant and Tomato}, volume={31}, ISSN={0890-037X 1550-2740}, url={http://dx.doi.org/10.1017/WET.2017.65}, DOI={10.1017/WET.2017.65}, abstractNote={Grafted plants are a combination of two different interspecific or intraspecific scion and rootstock. Determination of herbicidal selectivity of the grafted plant is critical given their increased use in vegetable production. Differential absorption, translocation, and metabolism play an important role in herbicide selectivity of plant species because these processes affect the herbicide amount delivered to the site of action. Therefore, experiments were conducted to determine absorption, translocation, and metabolism of halosulfuron in grafted and non-grafted tomato and eggplant. Transplant type included non-grafted tomato cultivar Amelia, non-grafted eggplant cultivar Santana, Amelia scion grafted onto Maxifort tomato rootstock (A-Maxifort) and Santana scion grafted onto Maxifort rootstock (S-Maxifort). Plants were treated POST with commercially formulated halosulfuron at 39 g ai ha-1followed by14C-halosulfuron under controlled laboratory conditions. Amount of14C-halosufuron was quantified in leaf wash, treated leaf, scion shoot, rootstock shoot, and root at 6, 12, 24, 48, and 96 h after treatment (HAT) using liquid scintillation spectrometry. No differences were observed between transplant types with regard to absorption and translocation of14C-halosulfuron. Absorption of14C-halosulfuron increased with time, reaching 10 and 74% of applied at 6 and 96 HAT, respectively. Translocation of14C-halosulfuron was limited to the treated leaf, which reached maximum (66% of applied) at 96 HAT, whereas minimal (<4% of applied) translocation occurred in scion shoot, rootstock shoot, and root. Tomato plants metabolized halosulfuron faster compared to eggplant regardless of grafting. Of the total amount of14C-halosulfuron absorbed into the plant, 9 to 14% remained in the form of the parent compound in tomato compared with 25 to 26% in eggplant at 48 HAT. These results indicate that grafting did not affect absorption, translocation, and metabolism of POST halosulfuron in tomato and eggplant.}, number={6}, journal={Weed Technology}, publisher={Cambridge University Press (CUP)}, author={Chaudhari, Sushila and Jennings, Katherine M. and Monks, David W. and Jordan, David L. and Gunter, Christopher C. and Louws, Frank J.}, year={2017}, month={Sep}, pages={908–914} }
 @article{suchoff_gunter_louws_2017, title={Comparative Analysis of Root System Morphology in Tomato Rootstocks}, volume={27}, ISSN={["1943-7714"]}, DOI={10.21273/horttech03654-17}, abstractNote={At its most basic, grafting is the replacement of one root system with another containing more desirable traits. Grafting of tomato (Solanum lycopersicum) onto disease-resistant rootstocks is an increasingly popular alternative for managing economically damaging soilborne diseases. Although certain rootstocks have demonstrated ancillary benefits in the form of improved tolerance to edaphic abiotic stress, the mechanisms behind the enhanced stress tolerance are not well understood. Specific traits within root system morphology (RSM), in both field crops and vegetables, can improve growth in conditions under abiotic stress. A greenhouse study was conducted to compare the RSM of 17 commercially available tomato rootstocks and one commercial field cultivar (Florida-47). Plants were grown in containers filled with a mixture of clay-based soil conditioner and pool filter sand (2:1 v/v) and harvested at 2, 3, or 4 weeks after emergence. At harvest, roots were cleaned, scanned, and analyzed with an image analysis system. Data collected included total root length (TRL), average root diameter, specific root length (SRL), and relative diameter class. The main effect of cultivar was significant (P ≤ 0.05) for all response variables and the main effect of harvest date was only significant (P ≤ 0.01) for TRL. ‘RST-106’ rootstock had the longest TRL, whereas ‘Beaufort’ had the shortest. ‘BHN-1088’ had the thickest average root diameter, which was 32% thicker than the thinnest, observed in ‘Beaufort’. SRL in ‘Beaufort’ was 60% larger than ‘BHN-1088’. This study demonstrated that gross differences exist in RSM of tomato rootstocks and that, when grown in a solid porous medium, these differences can be determined using an image analysis system.}, number={3}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Suchoff, David H. and Gunter, Christopher C. and Louws, Frank J.}, year={2017}, month={Jun}, pages={319–324} }
 @article{early season crop development, yield, and fruit quality of standard and mini watermelons grafted to several cucurbit rootstocks_2017, url={https://publons.com/wos-op/publon/56007345/}, journal={Hortscience}, year={2017} }
 @article{early season crop development, yield, and fruit quality of standard and mini watermelons grafted to several cucurbit rootstocks_2017, url={https://publons.com/wos-op/publon/56007349/}, journal={Hortscience}, year={2017} }
 @article{rahman_louws_2017, title={Epidemiological Significance of Crown Rot in the Fruiting Field in Relation to Colletotrichum gloeosporioides Infection of Strawberry Nursery Plants}, volume={101}, ISSN={["1943-7692"]}, DOI={10.1094/pdis-06-16-0802-re}, abstractNote={ Anthracnose crown rot (ACR), caused by Colletotrichum gloeosporioides, is a serious disease of strawberry (Fragaria × ananassa) in the southeastern United States, and there is a need to determine the link between nursery and fruiting-field disease risk. A 2-year study in 2007, repeated in 2008, was conducted at the North Carolina State University Horticultural Crops Research Station, Clinton, using ‘Chandler’, the most popular cultivar in North Carolina and one that is highly susceptible to ACR. Mother plants in a summer nursery were inoculated midseason with three pathogenic strains of C. gloeosporioides at an incidence level of 0, 5, 10, or 25%. Asymptomatic runner plants were selected at maturity (85 to 88 days after inoculation) from the nursery in early to mid-October from within a 0.5-m (inner) or 0.5- to 1.0-m (outer) radius around inoculated mother plants and planted into a plasticulture fruiting field system, with fruit harvest in April to June the following spring. Plants collected from the 25%-inner treatment had the greatest area under the disease progress curve (AUDPC) values, with a terminal ACR-related plant mortality of 32 and 20% by the end of fruit harvest and marketable yield losses of 30.5 and 30.2% in 2007–08 (Yr1) and 2008–09 (Yr2) seasons, respectively. All treatments increased AUDPC values compared with noninoculated treatments except the 10%-outer (O) and 5%-O treatments in Yr1 and Yr2, respectively. Marketable yield decreased 291.6 kg/ha for every percent increase in inoculum level (i.e., 0 to 25%, R2 = 0.696, P = 0.001). Levels of quiescent infection (QI) incidence (percentage of sampled leaves) assessed 25 to 28 days before digging runner plants also directly affected yield. For example, yield decreased 131.0 kg/ha for every percent increase in QI incidence in mother plants (R2 = 0.744, P = 0.001). Immersion of plants in fungicide solutions prior to planting decreased AUDPC values and improved plant stand by 7 to 11% but did not affect marketable yield compared with controls. This study provides results that can enable nursery and fruit growers to assess risk and implement mitigation measures to limit nursery plant and fruit yield losses. }, number={6}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Rahman, Mahfuzur and Louws, Frank J.}, year={2017}, month={Jun}, pages={907–915} }
 @article{influence of grafting on the critical period for weed control in grafted watermelon_2017, url={https://publons.com/wos-op/publon/35909164/}, journal={Hortscience}, year={2017} }
 @article{bhattarai_louws_williamson_panthee_2017, title={Resistance to Xanthomonas perforans
 race T4 causing bacterial spot in tomato breeding lines}, volume={66}, ISSN={0032-0862}, url={http://dx.doi.org/10.1111/ppa.12656}, DOI={10.1111/ppa.12656}, abstractNote={Tomato (Solanum lycopersicum) is the second most important vegetable crop in the world. Bacterial spot (BS) of tomato, caused by four species of Xanthomonas: X. euvesicatoria, X. vesicatoria, X. perforans and X. gardneri, results in severe loss in yield and quality due to defoliation and formation of lesions on fruits, respectively. Currently management practices do not offer effective control under conditions of high disease pressure. Thus, developing BS resistance is a critical priority for tomato growers in order to minimize crop losses. Sixty‐three advanced tomato breeding lines, heirlooms and wild tomato lines with diverse genetic backgrounds were screened under greenhouse and field conditions for BS resistance using X. perforans race T4, which was found to be a prevalent race in North Carolina. Race T4 isolate 9 was used to inoculate the plants by spraying, and disease severity was measured using the Horsfall–Barratt scale. Tomato lines 74L‐1W(2008), NC2CELBR, 081‐12‐1X‐gsms, NC22L‐1 (2008) and 52LB‐1 showed resistance to BS in the field and/or greenhouse trials. These lines were derived from S. pimpinellifolium L3707. Screening L3707 followed by development of a mapping population and mapping resistance genes might be useful for breeding resistance against BS in future breeding programmes.}, number={7}, journal={Plant Pathology}, publisher={Wiley}, author={Bhattarai, K. and Louws, F. J. and Williamson, J. D. and Panthee, D. R.}, year={2017}, month={Jan}, pages={1103–1109} }
 @article{chaudhari_jennings_monks_jordan_gunter_louws_2017, title={Response of Drought-Stressed Grafted and Nongrafted Tomato to Postemergence Metribuzin}, volume={31}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2017.12}, abstractNote={Tomato grafting is practiced worldwide as an innovative approach to manage stress from drought, waterlogging, insects, and diseases. Metribuzin is a commonly used herbicide in tomato but has potential to cause injury after application if plants are under stress. The influence of metribuzin on grafted tomato under drought-stress has not been studied. Greenhouse experiments were conducted in Raleigh, NC to determine the tolerance of drought-stressed grafted and non-grafted tomato to metribuzin. The tomato cultivar ‘Amelia’ was used as the scion in grafted tomato, and for the non-grafted control. Two hybrid tomato ‘Beaufort’ and ‘Maxifort’ were used as rootstocks for grafted plants. Drought-stress treatments included: no drought-stress; 3 d of drought-stress before metribuzin application with no drought-stress after application (3 d DSB); and 3 d of drought-stress before metribuzin application with 3 d of drought-stress after application (3 d DSBA). Metribuzin was applied at 550 g ai ha−1. No difference in injury from metribuzin was observed in grafted and non-grafted plants. However, at 7 and 14 d after metribuzin treatment (DMT), less injury was observed on tomato in the 3 d DSBA treatment (5 and 2% injury, respectively) than on plants in the 3 d DSB treatment (15 and 8% injury, respectively) or those that were never drought-stressed (18 and 11% injury, respectively). Photosynthesis and stomatal conductance measured prior to metribuzin application were reduced similarly in grafted and non-grafted tomato subjected to drought-stress. Photosynthesis and stomatal conductance of grafted and non-grafted tomato at 7 DMT was not different among drought-stress treatments or metribuzin treatments. Grafted and non-grafted tomato plants under drought-stress exhibit similar tolerance to metribuzin. The risk of metribuzin injury to grafted tomato under drought-stress is similar to non-grafted tomato.}, number={3}, journal={WEED TECHNOLOGY}, author={Chaudhari, Sushila and Jennings, Katherine M. and Monks, David W. and Jordan, David L. and Gunter, Christopher C. and Louws, Frank J.}, year={2017}, pages={447–454} }
 @article{rootstock-imparted water use efficiency in grafted heirloom tomatoes_2017, url={https://publons.com/wos-op/publon/56007339/}, journal={Hortscience}, year={2017} }
 @article{chaudhari_jennings_monks_jordan_gunter_mcgowen_louws_2016, title={Critical Period for Weed Control in Grafted and Nongrafted Fresh Market Tomato}, volume={64}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-15-00049.1}, abstractNote={Field experiments were conducted to determine the critical period for weed control (CPWC) in nongrafted ‘Amelia’ and Amelia grafted onto ‘Maxifort’ tomato rootstock grown in plasticulture. The establishment treatments (EST) consisted of two seedlings each of common purslane, large crabgrass, and yellow nutsedge transplanted at 1, 2, 3, 4, 5, 6, and 12 wk after tomato transplanting (WAT) and remained until tomato harvest to simulate weeds emerging at different times. The removal treatments (REM) consisted of the same weeds transplanted on the day of tomato transplanting and removed at 2, 3, 4, 5, 6, 8, and 12 WAT to simulate weeds controlled at different times. The beginning and end of the CPWC, based on a 5% yield loss of marketable tomato, was determined by fitting log-logistic and Gompertz models to the relative yield data representing REM and EST, respectively. In both grafted and nongrafted tomato, plant aboveground dry biomass increased as establishment of weeds was delayed and tomato plant biomass decreased when removal of weeds was delayed. For a given time of weed removal and establishment, grafted tomato plants produced higher biomass than nongrafted. The delay in establishment and removal of weeds resulted in weed biomass decrease and increase of the same magnitude, respectively, regardless of transplant type. The predicted CPWC was from 2.2 to 4.5 WAT in grafted tomato and from 3.3 to 5.8 WAT in nongrafted tomato. The length (2.3 or 2.5 wk) of the CPWC in fresh market tomato was not affected by grafting; however, the CPWC management began and ended 1 wk earlier in grafted tomato than in nongrafted tomato.}, number={3}, journal={WEED SCIENCE}, author={Chaudhari, Sushila and Jennings, Katherine M. and Monks, David W. and Jordan, David L. and Gunter, Christopher C. and McGowen, Samuel J. and Louws, Frank J.}, year={2016}, pages={523–530} }
 @article{bhattarai_louws_williamson_panthee_2016, title={Differential response of tomato genotypes to Xanthomonas-specific pathogen-associated molecular patterns and correlation with bacterial spot (Xanthomonas perforans) resistance}, volume={3}, DOI={10.1038/hortres.2016.35}, abstractNote={Plants depend on innate immune responses to retard the initial spread of pathogens entering through stomata, hydathodes or injuries. These responses are triggered by conserved patterns in pathogen-encoded molecules known as pathogen-associated molecular patterns (PAMPs). Production of reactive oxygen species (ROS) is one of the first responses, and the resulting ‘oxidative burst’ is considered to be a first line of defense. In this study, we conducted association analyses between ROS production and bacterial spot (BS; Xanthomonas spp.) resistance in 63 genotypes of tomato (Solanum lycopersicum L.). A luminol-based assay was performed on leaf tissues that had been treated with a flagellin 22 (flg22), flagellin 28 and a Xanthomonas-specific flg22 (flg22-Xac) peptide, to measure PAMP-induced ROS production in each genotype. These genotypes were also assessed for BS disease response by inoculation with Xanthomonas perforans, race T4. Although there was no consistent relationship between peptides used and host response to the BS, there was a significant negative correlation (r=−0.25, P<0.05) between foliar disease severity and ROS production, when flg22-Xac was used. This response could potentially be used to identify the Xanthomonas-specific PRR allele in tomato, and eventually PAMP-triggered immunity loci could be mapped in a segregating population. This has potential significance in tomato improvement.}, journal={Horticulture Research}, author={Bhattarai, K. and Louws, Frank J. and Williamson, J. D. and Panthee, Dilip}, year={2016} }
 @article{chaudhari_jennings_monks_jordan_gunter_basinger_louws_2016, title={Response of Eggplant (Solanum melongena) Grafted onto Tomato (Solanum lycopersicum) Rootstock to Herbicides}, volume={30}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-15-00079.1}, abstractNote={Tomato rootstocks have been successfully used for eggplant production. However, the safety of herbicides registered in tomato has not been tested on grafted eggplant, which is a combination of tomato rootstock and eggplant scion. Greenhouse and field experiments were conducted to determine response of grafted eggplant on tomato rootstock to napropamide, metribuzin, halosulfuron, trifluralin,S-metolachlor, and fomesafen herbicides. In greenhouse experiments, herbicide treatments included pretransplantS-metolachlor (400 and 800 g ai ha−1), pre- or posttransplant metribuzin (140 and 280 g ai ha−1), and posttransplant halosulfuron (18 and 36 g ai ha−1). In field experiments, herbicide treatments included pretransplant fomesafen (280 and 420 g ai ha−1), halosulfuron (39 and 52 g ha−1), metribuzin (280 and 550 g ha−1), napropamide (1,120 and 2,240 g ai ha−1),S-metolachlor (800 and 1,060 g ha−1), and trifluralin (560 and 840 g ai ha−1). The eggplant cultivar ‘Santana' was used as the scion and nongrafted control, and two hybrid tomatoes ‘RST-04−106-T' and ‘Maxifort' were used as rootstocks for grafted plants. In both greenhouse and field experiments, there was no difference between grafted and nongrafted eggplant in terms of injury caused by herbicides. Metribuzin posttransplant at 140 and 280 g ha−1caused 94 and 100% injury to grafted and nongrafted eggplant 4 wk after treatment. In field experiments, pretransplant fomesafen, napropamide,S-metolachlor, and trifluralin caused less than 10% injury and no yield reduction in grafted and nongrafted eggplant. However, metribuzin caused injury and yield reduction in both grafted and nongrafted eggplant. Metribuzin at 550 g ha−1caused 60 and 81% plant stand loss in 2013 and 2014, respectively. Halosulfuron reduced yield 24% in both grafted and nongrafted eggplant compared to nontreated control in 2013 but did not reduce yield in 2014. The pretransplantS-metolachlor, napropamide, fomesafen, and trifluralin are safe to use on eggplant grafted onto tomato rootstock, and will be a valuable addition to the toolkit of eggplant growers.}, number={1}, journal={WEED TECHNOLOGY}, author={Chaudhari, Sushila and Jennings, Katherine M. and Monks, David W. and Jordan, David L. and Gunter, Christopher C. and Basinger, Nicholas T. and Louws, Frank J.}, year={2016}, pages={207–216} }
 @article{liu_shen_wei_smith_louws_steadman_correll_2016, title={Rhizoctonia communities in soybean fields and their relation with other microbes and nematode communities}, volume={144}, ISSN={["1573-8469"]}, DOI={10.1007/s10658-015-0805-6}, number={3}, journal={EUROPEAN JOURNAL OF PLANT PATHOLOGY}, author={Liu, Bo and Shen, Weishou and Wei, Hsinho and Smith, Hosanna and Louws, Frank J. and Steadman, James R. and Correll, James C.}, year={2016}, month={Mar}, pages={671–686} }
 @article{characterization of root systems in tomato and tomato rootstocks through the use of mini-horhizotron technology_2015, url={https://publons.com/wos-op/publon/56007340/}, journal={Hortscience}, year={2015} }
 @article{rysin_louws_2015, title={Decision Tool for Growers to Evaluate Economic Impact of Grafting Technology Adoption: An Application to Open-field Conventional Tomato Production}, volume={25}, DOI={10.21273/horttech.25.1.132}, abstractNote={Grafting could potentially become an important part of integrated pest management programs in vegetable crops in the United States due to increased pathogen densities, reliance on pathogen susceptible varieties, increased use of organic and high tunnel production systems, limited land or input resources, value-added benefits, and the loss of, or regulatory restrictions on, soil fumigants. Adoption of this technology imposes additional costs on growers due to significantly higher grafted transplant prices, but associated yield improvements are potentially more than sufficient to offset the higher transplant costs. Therefore, the economic impact of the technology adoption depends highly on the specific circumstances of each grower. In this study, we propose a decision tool for growers to facilitate grafting technology adoption. We demonstrate an application of the proposed tool to a scenario based on real-life data for the open-field production of tomato (Solanum lycopersicum). The results show that based on a 30% loss in marketable yields due to disease pressure in nongrafted systems, yield improvements in the grafted system with resistant rootstock were sufficient to offset higher transplant and harvesting costs and resulted in higher net revenues. Net revenue estimates were $7126/acre in the nongrafted system and $8374/acre in the grafted system. The sensitivity analysis resulted in positive net revenues in the grafted system ranging from $108 to $12,328 per acre. Estimated marketable yield required in the grafted system to breakeven with the nongrafted system was 73,880 or 19,980 lb/acre more than marketable yield in the nongrafted system.}, number={1}, journal={HortTechnology}, publisher={American Society for Horticultural Science}, author={Rysin, Olya and Louws, Frank J.}, year={2015}, month={Feb}, pages={132–138} }
 @article{rysin_mcwhirt_fernandez_louws_schroeder-moreno_2015, title={Economic Viability and Environmental Impact Assessment of Three Different Strawberry Production Systems in the Southeastern United States}, volume={25}, DOI={10.21273/horttech.25.4.585}, abstractNote={In this study, we investigate the economic viability and environmental impact of three different soil management systems used for strawberry (Fragaria ×ananassa) production in the southeastern United States: 1) a conventional production system that is based on the current production practices implemented by growers, 2) a nonfumigated compost system with summer cover crop rotations and beneficial soil inoculants, and 3) an organic production system that includes practices approved for use under the National Organic Program (NOP). Under our assumptions, all three systems resulted in positive net returns estimated at $14,979, $11,100, and $19,394 per acre, respectively. The nonfumigated compost system and organic system also both resulted in considerable reductions in negative environmental and human health impacts measured by a set of selected indicators. For example, the total number of lethal doses (LD50) applied per acre from all chemicals used in each system and measuring acute human risk associated with each system declined from 118,000 doses/acre in the conventional system to 6649 doses/acre in the compost system and to 0 doses/acre in the organic system. Chronic human health risk, groundwater pollution risk, and fertilizer use declined as well in the compost and organic systems as compared with the conventional system.}, number={4}, journal={HortTechnology}, publisher={American Society for Horticultural Science}, author={Rysin, Olya and McWhirt, Amanda and Fernandez, Gina and Louws, Frank J. and Schroeder-Moreno, Michelle}, year={2015}, month={Aug}, pages={585–594} }
 @article{rysin_rivard_louws_2015, title={IS VEGETABLE GRAFTING ECONOMICALLY VIABLE IN THE UNITED STATES: EVIDENCE FROM FOUR DIFFERENT TOMATO PRODUCTION SYSTEMS}, volume={6}, DOI={10.17660/actahortic.2015.1086.8}, abstractNote={Four case studies representing distinct tomato (Solanum lycopersicum) production systems were selected, including conventional and organic field production, conventional production in multi-bay tunnels and organic production in high tunnels. Relevant cost and revenue information was collected. On-farm economic impact of grafting technology adoption was evaluated for each system. The primary objective was to use these real-life examples to investigate the forces that should be driving grower adoption decisions. A combination and interaction of multiple factors such as grafting transplant prices, expected yield improvements and sale prices guide adoption decisions. The use of grafted transplants generally resulted in positive net returns; conventional field tomato production and high tunnel organic tomato production were shown to be more sensitive to grafting transplant prices as they generally have lower profit margins. At high selling prices, growers can afford to pay price premiums for grafted transplants because only very modest yield improvements are required to compensate for higher costs of grafted plants. Use of grafted plants has potential economic benefits in all systems but actual outcome is dependent on multiple factors. INTRODUCTION The use of grafting in fruiting vegetables was first introduced in China in the 5 century (Lewis et al., 2014), while commercial use of vegetable grafting originated in Japan and Koreaabout 30 years ago and later expanded to Western countries (Kubota et al., 2008; Lee et al., 2010). Even though, the United States transplant production capacity is growing (Lee et al., 2010), vegetable grafting is still rare in field-based production systems due to the high cost of grafted transplants and lack of reliable information and local infrastructure (Barrett et al., 2012; King at al., 2010; Kubota et al., 2008; Taylor et al., 2008). The use of grafting is common with various vegetable species in both the Cucurbitaceae and Solanaceae families. A wide variety of rootstocks is available for specific conditions and environments (Lee et al., 2010). The use of grafted plants is seen primarily as a way to manage various soilborne pathogens in successive cropping systems (King et al., 2010; Kubota et al., 2008; Rivard and Louws, 2008) as there are commercially available rootstocks that exhibit resistance or tolerance to a number of diseases and nematodes. As a result of increased pathogen pressure, adoption of organic and high tunnel production systems, and the loss of methyl bromide as a soil fumigant, grafting is steadily becoming an important part of integrated pest management programs in vegetable crops (Barrett et al., 2012; King et al., 2010; Lee et al., 2010; Louws et al., 2010). In addition, growers may rely on grafting as a way to improve vigor, optimize absorption of water and nutrients, leading to improved use of limited resources (Djidonou et al., 2013a; Lee et al., 2010; Rivard and Louws, 2008), as a tool to manage abiotic frank_louws@ncsu.edu Proc. I IS on Vegetable Grafting Eds.: Zhilong Bie et al. Acta Hort. 1086, ISHS 2015 80 stress, to reduce the use of agricultural chemicals, and to enhance fruit quality (Lee et al., 2010). Tomato (Solanum lycopersicum) is the major crop currently grafted in North America (Kubota et al., 2008) primarily for vigor benefits in protected agriculture and for disease resistance (Barrett et al., 2012; King et al., 2010; Kubota et al., 2008; Rivard and Louws, 2008). In tomato production, rootstock selection for disease management, and therefore associated production and economic benefits of grafting, are site-specific and depend on various local pathogens, as well as edaphic, environmental and anthropogenic factors (Barrett et al., 2012; Louws et al., 2010). As a result, it is difficult to generate reliable scientific evidence directly relevant for all growers who seek to determine the benefits of grafting for their situation (Kubota et al., 2008; Rivard and Louws, 2008). High costs of grafted plants are often viewed as a barrier to adoption of grafted technology in the United States (Rivard et al., 2010). Studies investigating economic viability of grafting typically have a specific focus predetermined by location, crop, production system and issue addressed by the experiment. For example, Barrett et al. (2012) investigated the cost-effectiveness of grafting to overcome root-knot nematodes (Meloidogyne sp.) in the production of organic heirloom tomatoes in Florida’s sandy soils. Grafted plants demonstrated great potential for maintaining fruit yields and reducing economic losses at high levels of infestation but were not economically feasible when used in fields with low nematode pressure. Taylor et al. (2008) arrived to a similar conclusion: it is not economically feasible for farmers growing seedless watermelon (Citrullus lanatus) to use grafted transplants if Fusarium wilt caused by Fusarium oxysporum is not an issue. Djidonou et al. (2013b) evaluated the impact of grafting on fresh-market tomato production under common management practices in North Florida in fumigated fields. They showed that grafting increased production costs considerably compared to the non-grafted system. However, net returns were higher in the grafted system due to yield improvements, but varied considerably depending on seasonal yields and market prices. A useful tool that could help growers make decisions about grafting is to provide a comparison of economic impacts of grafting across different production systems. We selected four case studies representing different tomato production systems capturing tomato production diversity in eastern United States: conventional field production, organic field heirloom tomato production, organic heirloom tomato production in high tunnels, and conventional heirloom tomato production in large multi-bay tunnels. Our primary objective is to investigate economic impact of grafting in these case studies and the forces that should be driving grower adoption decisions based on their specific economic circumstances. MATERIALS AND METHODS It was noted earlier that economic benefits of grafting are specific to the site and depend on various local environmental and economic factors. In addition, there exists great variability in the economic circumstances of different tomato production systems and sites. Selected case studies capture some diversity in tomato production in eastern United States. Conventional field production is the predominant system in the Southeast and is often characterized as large scale and orientated towards wholesale markets. Field and high tunnel organic heirloom tomato production systems are typically a part of highly diversified farms and are oriented towards specialized markets and local direct marketing. Finally, production of conventional heirloom tomatoes in multi-bay tunnels varies in scale and could be oriented towards both wholesale and specialty markets. In the case of multibay tunnels, frame construction is less expensive compared to high tunnels and can cover larger growing blocks. For each case study, we collected information on production, transplant and harvesting costs, expected yields and sale prices, and estimated revenues. Production cost models were developed based on customary management practices recommended by extension and research horticultural specialists and practiced by growers. These models}, number={1086}, journal={Acta Horticulturae}, publisher={International Society for Horticultural Science (ISHS)}, author={Rysin, O. and Rivard, C. and Louws, F.J.}, year={2015}, month={Jun}, pages={79–86} }
 @article{impacts of biofumigation and anaerobic soil disinfestation in strawberry production_2015, url={https://publons.com/wos-op/publon/56007344/}, journal={Hortscience}, year={2015} }
 @article{impacts of biofumigation and anaerobic soil disinfestation on strawberry plant nutrition and fruit quality_2015, url={https://publons.com/wos-op/publon/56007350/}, journal={Hortscience}, year={2015} }
 @article{rahman_ojiambo_louws_2015, title={Initial Inoculum and Spatial Dispersal of Colletotrichum gloeosporioides, the Causal Agent of Strawberry Anthracnose Crown Rot}, volume={99}, ISSN={["1943-7692"]}, DOI={10.1094/pdis-02-13-0144-re}, abstractNote={ Anthracnose crown rot (ACR), caused by Colletotrichum gloeosporioides, is a serious disease of strawberry (Fragaria × ananassa) in nurseries and fruiting fields in the southeastern United States. This study was conducted to determine the potential of alternative hosts for initial inoculum source and spread that causes ACR in strawberry nurseries. Results indicated that Parthenocissus quinquefolia is a noncultivated host of C. gloeosporioides in North Carolina and may serve as an initial inoculum source for planting material. Sources of inoculum data were complemented with a 2-year study of disease incidence and spread in simulated nursery production experiments. Sixty days after inoculation of the mother plants in the nursery, three different inoculation levels showed a significant positive correlation (r = 0.78, P < 0.004) with the quiescent infection (QI) incidence on the runner or daughter plants at the end of the nursery production cycle. Runner plant counts from different proportion of mother plants' inoculation treatments indicated that runner plant production was negatively and significantly (P < 0.001) affected by C. gloeosporioides. Infected tips used to produce transplants destined for fruit production resulted in 29.3 and 16.8% mortality in plug trays in 2007 and 2008, respectively. Tracking foliar QI incidence that resulted from dispersal of inoculum from an introduced point source in the nursery showed a sharp decline at 1 m and beyond from the inoculation focus. Although the exponential model (R2 = 0.92 to 0.94) had slightly higher coefficients of determination than the modified power law (R2 = 0.89 to 0.90), residual plots indicated that the modified power law model fit the disease gradient data better than the exponential model in both years. Results from our dispersal study indicated that rogueing of infected plants within a 4-m radius of infection foci would reduce the risk of transferring infected runner plants from the nursery to the fruiting field. }, number={1}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Rahman, Mahfuzur and Ojiambo, Peter and Louws, Frank}, year={2015}, month={Jan}, pages={80–86} }
 @article{integrated pest information platform for extension and education (ipipe): a new usda cooperative agricultural program (cap)_2015, url={https://publons.com/wos-op/publon/56007348/}, journal={Phytopathology}, year={2015} }
 @article{population genetic analysis of early blight pathogen, alternaria solani from tomato and potato_2015, url={https://publons.com/wos-op/publon/56007347/}, journal={Phytopathology}, year={2015} }
 @article{chaudhari_jennings_monks_jordan_gunter_louws_2015, title={Response of Grafted Tomato (Solanum lycopersicum) to Herbicides}, volume={29}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-15-00037.1}, abstractNote={Tomato grafting has gained increased attention in the United States as an alternative to methyl bromide to control soilborne pests and diseases. Although several herbicides are registered in tomato production, a lack of information exists on the effect of herbicides on grafted tomato. Greenhouse and field experiments were conducted to determine herbicide tolerance of grafted tomato. In greenhouse experiments, halosulfuron (27, 54, and 108 g ai ha−1), metribuzin (280, 560, and 1,120 g ai ha−1), andS-metolachlor (1,070, 2,140, and 3,200 g ai ha−1) were applied posttransplant to nongrafted ‘Amelia' and Amelia scion grafted onto ‘Maxifort' or ‘RST-04-106-T' tomato rootstocks. Although herbicide injury was observed, no differences were observed in grafted and nongrafted tomato response including visible injury assessments, plant height, and fresh weight. Tomato injury at 3 wk after herbicide application increased from 3 to 12, 1 to 87, and 0 to 37% as rate of halosulfuron, metribuzin, andS-metolachlor increased, respectively. In field experiments under plasticulture, herbicides applied pretransplant included fomesafen (280 and 420 g ai ha−1), halosulfuron (39 and 54 g ha−1), metribuzin (280 and 560 g ha−1), napropamide (1,120 and 2,240 g ha−1),S-metolachlor (800 and 1,070 g ha−1), and trifluralin (560 and 840 g ai ha−1). Amelia was used as the scion and the nongrafted control. ‘Anchor-T', ‘Beaufort', or Maxifort tomato were used as rootstocks for grafted plants. Fomesafen, halosulfuron, napropamide, and trifluralin initially caused greater injury to grafted tomato than to nongrafted tomato regardless of rootstock (Anchor-T, Beaufort, or Maxifort). However, by 4 wk after treatment, all grafted and nongrafted plants had recovered from herbicide injury. A transplant type-by-herbicide interaction was not observed for yield, but grafted A-Maxifort tomato produced greater total and marketable yield than nongrafted Amelia tomato. Grafted tomato exhibited similar tolerance as nongrafted tomato for all herbicides applied post- and pretransplant.}, number={4}, journal={WEED TECHNOLOGY}, publisher={Cambridge University Press (CUP)}, author={Chaudhari, Sushila and Jennings, Katherine M. and Monks, David W. and Jordan, David L. and Gunter, Christopher C. and Louws, Frank J.}, year={2015}, pages={800–809} }
 @article{response of grafted tomato to nitrogen_2015, url={https://publons.com/wos-op/publon/56007341/}, journal={Hortscience}, year={2015} }
 @article{suchoff_louws_gunter_schultheis_2014, title={2013 On-farm Grafted Tomato Trial to Manage Bacterial Wilt}, volume={1086}, ISSN={["0567-7572"]}, DOI={10.17660/actahortic.2015.1086.14}, abstractNote={Grossing over $33.7 million in annual sales, North Carolina ranks 7th in the US for the production of tomatoes (Solanum lycopersicum). A replicated on-farm trial was conducted in Rowan County, NC. On May 30th, 2013, 8.1 ha of two bacterial wilt (BW; R. solanacearum (race 1)) resistant rootstocks were planted. The objective of this trial was to evaluate disease susceptibility and production in fields with BW history. In addition, plant spacing and training systems were compared. Two experimental sites, one fumigated and one non-fumigated, were arranged in a randomized complete block design with four replications, each consisting of 91.4 m-rows in a commercial plasticulture system. Each row contained 13 10-plant treatment plots (2A—2A—3 Factorial + Control): two rootstocks (‘801’, ‘802’; Rijk Zwaan), two training systems (single-leader, double-leaders), three between-plant spacings (45.7, 61.0, and 76.2 cm) with ‘Mountain Fresh’ as the scion and a non-grafted ‘Mountain Fresh’ control spaced at 45.7 cm. Wilt incidence was collected during the two harvests. Fruit were harvested twice at 69 and 84 days after transplanting. Wilt incidence was lower in the non-fumigated field and no differences in yield between the grafted and non-grafted plants were observed. In the fumigated field, the main effect of grafting tended to increase yield. Both the main effect of training system and spacing significantly affected yield in the grafted treatments. BW incidence was significantly higher in the non-grafted treatment (29.08%) than ‘801’ and ‘802’ rootstocks (0.909 and 0.183%, respectively) (P<.0001). Single-leader grafted plants had 2.54% more BW incidence than double-leader plants (P=0.0007). Grafted tomatoes offered an alternative method to fumigation as a means to reduce BW loss and sustain marketable yield.}, number={1086}, journal={Acta Horticulturae (ISHS)}, publisher={International Society for Horticultural Science (ISHS)}, author={Suchoff, D.H. and Louws, F.J. and Gunter, C.C. and Schultheis, J.R.}, year={2014}, pages={119–127} }
 @article{critical period for weed control in grafted versus nongrafted tomato_2014, url={https://publons.com/wos-op/publon/56007352/}, journal={Hortscience}, year={2014} }
 @article{screening of tomato (<i>solanum lycopersicum</i> l.) lines for bacterial spot (<i>xanthomonas species</i>) resistance_2014, url={https://publons.com/wos-op/publon/51538733/}, journal={Hortscience}, year={2014} }
 @article{tomato rootstock resistance to bacterial wilt (ralstonia solanacearum): effects of genotype and cold stress on epidemic profile_2014, url={https://publons.com/wos-op/publon/51538732/}, journal={Hortscience}, year={2014} }
 @article{adhikari_hodges_louws_2013, title={First Report of Cylindrocarpon sp Associated with Root Rot Disease of Strawberry in North Carolina}, volume={97}, ISSN={["0191-2917"]}, DOI={10.1094/pdis-01-13-0116-pdn}, abstractNote={ Strawberry (Fragaria × ananassa Duchesne) is an economically important fruit crop in North Carolina for domestic consumption and export. In April 2012, outbreaks of a destructive root disease were observed in strawberry cv. Chandler in Buncombe, New Hanover, and Roman counties, North Carolina. Samples from Rowan (ID 13175) and Buncombe (ID 13193) counties submitted to the Plant Disease and Insect Clinic of the Department of Plant Pathology, North Carolina State University, exhibited yellowing and wilting of leaves and extensive root necrosis, and disease severity based on field symptoms ranged from 20 to 30%. To identify the pathogen, five small pieces of necrotic crown and root tissues were taken from each sample, surface disinfested for 1 min in a 1.5% sodium hypochlorite solution, and plated onto potato dextrose agar (PDA) with 0.5 g liter–1 of streptomycin sulfate. Colonies developing from the tissue samples were transferred to PDA. Colonies from both samples were identical, grew relatively slowly, and gradually turned yellowish to partially brownish. After about 7 days, abundant conidia were formed. These were hyaline, mostly straight with both ends rounded, predominantly three septate, and 40 to 50 × 5 to 10 μm. Based on morphological characteristics, these isolates were identified as a species of Cylindrocarpon (1) To confirm the original identification of the fungus as a species of Cylindrocarpon, genomic DNA of both isolates was extracted from mycelia using DNeasy Plant Mini Kit (Qiagen Inc., Valencia, CA) and analyzed using PCR (2). The internal transcribed spacers (ITS)1 and (ITS)2 flanking the 5.8S rRNA regions were amplified and sequenced using universal primers ITS1 (forward) and ITS4 (reverse). The sequences of the 421 bp (GenBank KC847090 and KC847091) of both isolates were identical. Furthermore, a BLASTn search of these sequences showed homology of 99% with the sequences of Cylidrocarpon species (AB369421.1, AM419069.1, AM419074.1, AY295332.1, JN031017.1, JN253505.1, and JQ886422.1), To fulfill Koch's postulates, inoculum of each isolate was prepared and adjusted to 1.5 × 107 conidia/ml using a hemacytometer. ‘Chandler’ strawberry plants were grown in 25-cm diameter plastic pots (one seedling per pot) in the greenhouse and five 6-week-old plants were injected with conidia of each isolate into the base of crown using a 5-ml syringe. The plants were covered with clear plastic for 24 h and left on the greenhouse bench with a 16-h photoperiod and 25/20°C day/night temperatures and assessed for disease development 14 days after inoculation. The inoculated plants exhibited wilting and root necrosis, consistent with the symptoms observed on strawberry plants in the field. Control plants treated with distilled water remained healthy. Isolations were made from the inoculated plants and the fungus used for inoculation was recovered from all plants. The morphology of these isolates was in agreement with published descriptions of Cylindrocarpon (1). To our knowledge, this is the first report of a Cylindrocarpon sp. causing crown and root rot on strawberry in North Carolina and effective disease management strategies need to be explored. }, number={9}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Adhikari, T. B. and Hodges, C. S. and Louws, F. J.}, year={2013}, month={Sep}, pages={1251–1251} }
 @article{liu_louws_2013, title={Multiple divergent ITS1 copies were identified in single tomato genome using DGGE analysis}, volume={31}, number={2}, journal={Plant Molecular Biology Reporter}, author={Liu, B. and Louws, F.}, year={2013}, pages={272–279} }
 @article{organic gardening educational materials for extension master gardener volunteers_2013, url={https://publons.com/wos-op/publon/56007346/}, journal={Hortscience}, year={2013} }
 @article{liu_louws_sutton_correll_2012, title={A rapid qualitative molecular method for the identification of Colletotrichum acutatum and C. gloeosporioides}, volume={132}, ISSN={["1573-8469"]}, DOI={10.1007/s10658-011-9904-1}, number={4}, journal={EUROPEAN JOURNAL OF PLANT PATHOLOGY}, author={Liu, Bo and Louws, Frank J. and Sutton, Turner B. and Correll, James C.}, year={2012}, month={Apr}, pages={593–607} }
 @article{rivard_s. o'connell_peet_welker_louws_2012, title={Grafting Tomato to Manage Bacterial Wilt Caused by Ralstonia solanacearum in the Southeastern United States}, volume={96}, ISSN={["1943-7692"]}, DOI={10.1094/pdis-12-10-0877}, abstractNote={ Bacterial wilt, caused by Ralstonia solanacearum, can result in severe losses to tomato (Solanum lycopersicum) growers in the southeastern United States, and grafting with resistant rootstocks may be an effective strategy for managing this disease. However, R. solanacearum populations maintain considerable diversity, and little information is known regarding the efficacy of commercially available rootstocks to reduce bacterial wilt incidence and subsequent crop loss in the United States. In this study, tomato plants grafted onto ‘Dai Honmei’ and ‘RST-04-105-T’ rootstocks had significantly lower area under the disease progress curve (AUDPC) values compared with nongrafted plants (P < 0.05). Across three locations in North Carolina, final bacterial wilt incidence for non- and self-grafted plants was 82 ± 14 to 100%. In contrast, bacterial wilt incidence for the grafted plants was 0 to 65 ± 21%. Final bacterial wilt incidence of plants grafted with Dai Honmei rootstock was 0 and 13 ± 3% at two locations in western North Carolina but 50 ± 3% at a third site in eastern North Carolina. Similarly, grafting onto RST-04-105-T rootstock significantly reduced AUDPC values at two of the three locations (P < 0.05) compared with that of the nongrafted plants, but performed poorly at the third site. Total fruit yields were significantly increased by grafting onto resistant rootstocks at all three sites (P < 0.05). Regression analyses indicated that yield was significantly negatively correlated with bacterial wilt AUDPC values (R2 was 0.4048 to 0.8034), and the use of resistant rootstocks enabled economically viable tomato production in soils naturally infested with R. solanacearum. }, number={7}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Rivard, C. L. and S. O'Connell and Peet, M. M. and Welker, R. M. and Louws, F. J.}, year={2012}, month={Jul}, pages={973–978} }
 @article{o'connell_rivard_peet_harlow_louws_2012, title={High Tunnel and Field Production of Organic Heirloom Tomatoes: Yield, Fruit Quality, Disease, and Microclimate}, volume={47}, ISSN={["2327-9834"]}, DOI={10.21273/hortsci.47.9.1283}, abstractNote={Organic and heirloom tomatoes are high-value products with growing demand but there are many challenges to successful cultivation. A systems comparison study was carried out to evaluate the production of the popular heirloom tomato ‘Cherokee Purple’ (Solanum lycopersicum L.) under high tunnel and open field systems in North Carolina from 2007 to 2008. Management of the high tunnel (i.e., temperature and irrigation), weather events as well as pest and disease pressure influenced crop quality and yield. The high tunnel and field systems achieved similar total yields (100 t·ha−1) the first season but yields were 33% greater in the high tunnel system than the field system in the second year (100 t·ha−1 and 67 t·ha−1, respectively). Both years, the tomatoes were planted in high tunnels 1 month earlier and harvested 3 weeks earlier than the field. The accumulation of ≈1100 growing degree-days (GDD) was required in both systems before 50% of the fruit was harvested. Fruit cracking, cat-facing, blossom-end rot, and insect damage were the major categories of defects in both systems. Incidence of both Tomato Spotted Wilt Virus (TSWV) and Gray Leaf Spot (GLS) were lower in the high tunnel compared with the field in 2007 and 2008, respectively. Results of this study suggest that with proper management techniques, high tunnels can optimize yields, increase fruit quality, and provide season extension opportunities for high-value horticultural crops.}, number={9}, journal={HORTSCIENCE}, publisher={American Society for Horticultural Science}, author={O'Connell, Suzanne and Rivard, Cary and Peet, Mary M. and Harlow, Chris and Louws, Frank}, year={2012}, month={Sep}, pages={1283–1290} }
 @article{liu_roos_buttler_richter_louws_2012, title={Vegetable Seedling Diseases Associated with Earthworm Castings Contaminated with Phytophthora capsici and Pythium Attrantheridium}, volume={13}, DOI={10.1094/php-2012-0421-01-rs}, abstractNote={ Earthworms and worm castings have been recommended for their beneficial effects in increasing yields and suppressing soilborne diseases. However, in a few cases, earthworm castings have been shown to harbor soilborne pathogens. The research documents that earthworm castings used as an amendment in soilless potting mixes at several organic farms in North Carolina were contaminated with Phytophthora capsici and several Pythium species. Phytophthora capsici and P. attrantheridium were subsequently isolated from rotted roots of vegetable seedlings grown in the potting mix. Commercial producers of earthworm castings should only use clean plant material to maintain earthworms and earthworm castings should be ascertained as pathogen-free before incorporation into plant growth media. }, number={1}, journal={Plant Health Progress}, publisher={Scientific Societies}, author={Liu, Bo and Roos, Debbie and Buttler, Shawn and Richter, Brantlee and Louws, Frank J.}, year={2012}, month={Jan}, pages={15} }
 @article{liu_munster_johnson_louws_2011, title={First Report of Anthracnose Caused by Colletotrichum fragariae on Cyclamen in North Carolina}, volume={95}, DOI={10.1094/pdis-06-11-0475}, abstractNote={ In November 2009, cyclamen (Cyclamen persicum) plants with disease symptoms from a commercial greenhouse operation in the western part of North Carolina were sent to the Plant Diseases and Insect Clinic at North Carolina State University. Symptoms consisted of coalescing reddish and tan necrotic leaf spots with concentric circles. Other symptoms included darkened vascular tissue and decay of the corm, large roots, and petioles. Diseased leaves and stems were surface sterilized in 0.5% sodium hypochlorite for 3 min, air dried, and placed in petri dishes containing alkaline water agar. After 3 days of incubation at room temperature, fungal colonies were transferred to acidified potato dextrose agar. Isolation frequency after 5 days was 33% (three of nine pieces) and 16% (one of six pieces) from small leaf spots and petioles, respectively. Pure cultures of isolates were gray and black with abundant, aerial, gray whitish mycelia. Diseased plants were also incubated in a moist chamber at room temperature and sporulation was observed within 7 days. Conidia were tapered with rounded ends and produced in the acervulus and on the tips of setae, which is consistent with the morphology of described isolates of Colletotrichum fragariae. Similar setae were also observed directly on the fine roots of the original sample. The pathogenicity of single-spore cultures was tested by spraying four 2-month-old cyclamen plants with a conidial suspension (106 conidia/ml) and the plants were kept in a humid chamber for 24 h. Noninoculated controls (four plants) were sprayed with distilled water and subjected to the same conditions. The pathogenicity test was also repeated. Inoculated plants and controls were placed in a greenhouse with a temperature range from 22 to 25°C. After 7 to 10 days, symptomatic leaves and stems were observed on all the inoculated plants but not on the control plants. Fungi reisolated from 10 symptomatic leaf tissues had identical morphological features as the original isolates. Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits following the manufacturer's protocol (Qiagen Inc., Valencia, CA). Sequence analysis of the rRNA internal transcribed spacer (ITS) region of the cyclamen isolate (GenBank Accession No. HQ188923), based on the fragment amplified with ITS1 and ITS4 primers, showed 100% similarity to isolates of C. fragariae deposited in GenBank (Accession Nos. FJ172290 [ATCC MYA-4443 from cyclamen] and FJ810510 [ATCC MYA-4442 from silver date palm]) and Florida isolate C16 isolated from strawberry (1). In addition, the morphology and ITS sequences of the cyclamen isolate were identical to those of the C. fragariae voucher isolate from strawberry (GU174546). Results from disease symptoms, colony and spore morphology, pathogenicity tests, and ITS sequence analysis suggest that C. fragariae was the pathogen responsible for the disease symptoms on cyclamens. To our knowledge, this is the first report of a disease caused by C. fragariae on cyclamen in North Carolina and complements an earlier report from Florida (1). }, number={11}, journal={Plant Disease}, publisher={Scientific Societies}, author={Liu, B. and Munster, M. and Johnson, C. and Louws, F. J.}, year={2011}, month={Nov}, pages={1480–1480} }
 @article{rivard_sydorovych_o'connell_peet_louws_2010, title={An Economic Analysis of Two Grafted Tomato Transplant Production Systems in the United States}, volume={20}, ISSN={["1943-7714"]}, DOI={10.21273/horttech.20.4.794}, abstractNote={The grafting of herbaceous vegetables is an emerging development in the United States. This report provides an estimate of the variable costs of grafting within U.S. tomato (Solanum lycopersicum) transplant production systems. Grafted and nongrafted plants were propagated at two commercial farming operations in Ivanhoe, NC (NC) and Strasburg, PA (PA) and the farm in NC produced certified organic transplants. Detailed economic production sequences were generated for each site, and grafted and nongrafted transplant production costs were $0.59 and $0.13 in NC, and $1.25 and $0.51 in PA, respectively. Direct costs associated with grafting (e.g., grafting labor, clips, chamber, etc.) accounted for 37% to 38% of the added cost of grafting, and grafting labor was 11.1% to 14.4% of the cost of grafted transplant production. Seed costs represented 52% and 33% of the added cost of grafting at the two sites, and indirect costs (e.g., soil, trays, and heating) accounted for 10% and 30% of the added cost of grafting. Our findings suggest that under current seed prices and with similar production practices, the feasibility of grafting in the United States is not disproportionately affected by domestic labor costs. Additionally, the economic models presented in this report identify the cost of production at various transplant stages, and provide a valuable tool for growers interested in grafted tomato transplant production and utilization.}, number={4}, journal={HORTTECHNOLOGY}, publisher={American Society for Horticultural Science}, author={Rivard, Cary L. and Sydorovych, Olha and O'Connell, Suzanne and Peet, Mary M. and Louws, Frank J.}, year={2010}, month={Aug}, pages={794–803} }
 @article{rivard_s. o'connell_peet_louws_2010, title={Grafting Tomato with Interspecific Rootstock to Manage Diseases Caused by Sclerotium rolfsii and Southern Root-Knot Nematode}, volume={94}, ISSN={["1943-7692"]}, DOI={10.1094/pdis-94-8-1015}, abstractNote={ Southern blight (Sclerotium rolfsii) and root-knot nematodes (Meloidogyne spp.) cause severe damage to fresh-market tomato (Solanum lycopersicum) throughout the southeastern United States. Grafting is an emerging technology in U.S. tomato production, and growers require information regarding the resistance characteristics conferred by rootstocks. In this study, southern blight (SB) and root-knot nematodes (RKN) were effectively managed using interspecific hybrid rootstocks. During 2007 and 2008, field trials were carried out at two locations that had soils naturally infested with S. rolfsii. At the end of the growing seasons, the mean SB incidence of nongrafted plants was 27 and 79% at the two sites. SB incidence among plants grafted onto rootstock cultivars Big Power (one location only), Beaufort, and Maxifort ranged from 0 to 5%, and area under the disease progress curve (AUDPC) values were lower than for nongrafted and self-grafted controls (P < 0.01). At one location, soils were naturally infested with RKN, and all three rootstocks reduced RKN AUDPC and RKN soil populations at first harvest (P < 0.01). Big Power was particularly effective at reducing RKN galling and RKN soil populations at final fruit harvest (P < 0.01). Fruit yield was higher when resistant rootstocks were utilized (P < 0.05), and in our study grafting was effective at maintaining crop productivity in soils infested with S. rolfsii and M. incognita. }, number={8}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Rivard, C. L. and S. O'Connell and Peet, M. M. and Louws, F. J.}, year={2010}, month={Aug}, pages={1015–1021} }
 @misc{louws_rivard_kubota_2010, title={Grafting fruiting vegetables to manage soilborne pathogens, foliar pathogens, arthropods and weeds}, volume={127}, ISSN={["1879-1018"]}, DOI={10.1016/j.scienta.2010.09.023}, abstractNote={Grafting is an important integrated pest management strategy to manage soilborne pathogens and other pests of solanaceous and cucurbitaceous crops. Important diseases managed by grafting are caused by fungal pathogens such as Verticillium, Fusarium, Pyrenochaeta and Monosporascus; oomycete pathogens like Phytophthora; bacterial pathogens, particularly Ralstonia; root knot nematodes and several soil-borne virus pathogens. Rootstocks can include intraspecific selections that utilize specific major resistance genes and interspecific and intergeneric selections that exploit non-host resistance mechanisms or multigenic resistance. Rootstock selection has also been documented to impact foliar pests including pathogens, arthropods and viruses. Over-reliance on specific rootstocks in production systems has led to the emergence of new pathogens or shifts in the host specificity of the pathogen population, emphasizing the need for multi-tactic approaches to manage soilborne pathogens. One advantage and associated challenge of grafting is that rootstock selection for disease management is site specific depending on the presence, population structure and dynamics of the pathogen, as well as edaphic, environmental and anthropogenic factors. The use of grafting as an Integrated pest management tool to manage biotic stress will be most successful when carried out with increasing knowledge about the biology, diversity, and population dynamics of the pathogen or other pests and when complemented with sustainable farming system practices. This review highlights major uses of grafting to manage soilborne pathogens, provides some novel information on managing foliar or other soilborne pests (insects, mites, weeds) and offers discussion on future research and applications.}, number={2}, journal={SCIENTIA HORTICULTURAE}, publisher={Elsevier BV}, author={Louws, Frank J. and Rivard, Cary L. and Kubota, Chieri}, year={2010}, month={Dec}, pages={127–146} }
 @article{louws_2009, title={IPM for Soilborne Disease Management for Vegetable and Strawberry Crops in SE USA}, DOI={10.1007/978-1-4020-8804-9_16}, journal={Recent Developments in Management of Plant Diseases}, publisher={Springer Netherlands}, author={Louws, Frank J.}, year={2009}, month={Aug}, pages={217–227} }
 @article{sydorovych_safley_welker_ferguson_monks_jennings_driver_louws_2008, title={Economic evaluation of methyl bromide alternatives for the production of tomatoes in North Carolina}, volume={18}, number={4}, journal={HortTechnology}, author={Sydorovych, O. and Safley, C. D. and Welker, R. M. and Ferguson, L. M. and Monks, D. W. and Jennings, K. and Driver, J. and Louws, F. J.}, year={2008}, pages={705–713} }
 @article{rivard_louws_2008, title={Grafting to Manage Soilborne Diseases in Heirloom Tomato Production}, volume={43}, ISSN={["2327-9834"]}, DOI={10.21273/hortsci.43.7.2104}, abstractNote={Organic heirloom tomato production is limited in the southeastern United States by foliar and soilborne diseases, thermal stress, and weathered soil structure. Heirloom cultivars command a premium market, but tolerance to disease and abiotic stress is often poor. Organic growers need research that supports the advantages of market niches afforded by heirloom tomatoes through the development of integrated systems to manage pests and reduce risks of associated crop losses or low yields. Two major soilborne diseases common in the southeast, bacterial wilt (caused by Ralstonia solanacearum) and fusarium wilt (caused by Fusarium oxysporum f.sp. lycopersici), were effectively managed using susceptible heirloom scions grafted onto resistant rootstock. In naturally infested soil, bacterial wilt incidence for nongrafted ‘German Johnson’ was 79% and 75% in 2005 and 2006, respectively. ‘German Johnson’ showed no symptoms of bacterial wilt in either year when grafted onto the resistant genotypes CRA 66 or Hawaii 7996. Fusarium wilt incidence was 46% and 50%, respectively, in nongrafted and self-grafted ‘German Johnson’ controls. When ‘Maxifort’ rootstock was grafted with ‘German Johnson’, no symptoms of fusarium wilt were seen, and plants with ‘Robusta’ rootstock had an intermediate level of disease (29%). An evaluation of commercially available rootstock was carried out in three separate experiments in diverse organic production systems to determine yield impacts with low disease pressure. ‘Maxifort’ rootstock significantly increased yield in one location (P = 0.05), but ‘Maxifort’ and ‘Robusta’ rootstock did not consistently impact yield at the other two locations. Grafting is an effective management tool for organic growers in the southeast United States to reduce risk of crop loss resulting from soilborne diseases and will be a valuable component in an integrated pest management program.}, number={7}, journal={HORTSCIENCE}, publisher={American Society for Horticultural Science}, author={Rivard, Cary L. and Louws, Frank J.}, year={2008}, month={Dec}, pages={2104–2111} }
 @article{abad_abad_coffey_oudemans_man in ’t veld_de gruyter_cunnington_louws_2008, title={Phytophthora bisheria sp. nov., a new species identified in isolates from the Rosaceous raspberry, rose and strawberry in three continents}, volume={100}, ISSN={0027-5514 1557-2536}, url={http://dx.doi.org/10.1080/15572536.2008.11832502}, DOI={10.1080/15572536.2008.11832502}, abstractNote={A homothallic semipapillate slow growing Phytophthora species associated with root rot of strawberries from greenhouse-grown plants in North Carolina, USA, root rot of roses in the Netherlands, and root rot of raspberry in Knoxfield, Australia, was identified. The main character of this organism is the production of paragynous antheridia with broad attachment to the oogonial wall. The morphology of the pathogen does not match that of any of the more than 85 described Phytophthora species. Phylogenetic analysis based on sequences of the internal transcribed spacer rDNA region (ITS1-5.8S-ITS2) of this taxon and those from other Phytophthora species from GenBank supports the conclusion that this organism is an unreported new species. In the phylogenetic tree with other reported Phytophthora species at the GenBank, the new species is more closely related to others in ITS clade 2 comprising semipapillate taxa including P. botryosa, P. citrophthora, P. colocasiae, P. meadii, P. citricola, P. inflata, P.tropicalis, P. capsici, Phytophthora sp. ‘glovera’ and P. multivesiculata. The most closely related species is P. multivesiculata isolated from Cymbidium orchid in the Netherlands. In this paper we describe the morphological characteristics and the phylogenetic relationships that support the description of this taxon as a new species Phytophthora bisheria sp. nov.}, number={1}, journal={Mycologia}, publisher={Informa UK Limited}, author={Abad, Z. Gloria and Abad, Jorge A. and Coffey, Michael D. and Oudemans, Peter V. and Man in ’t Veld, Willem A. and de Gruyter, Hans and Cunnington, James and Louws, Frank J.}, year={2008}, month={Jan}, pages={99–110} }
 @article{abad_abad_coffey_oudemans_man_gruyter_cunnington_louws_2008, title={Phytophthora bishetia sp nov., a new species identified in isolates from the Rosaceous raspberry, rose and strawberry in three continents}, volume={100}, ISSN={["1557-2536"]}, DOI={10.3852/mycologia.100.1.99}, abstractNote={A homothallic semipapillate slow growing Phytophthora species associated with root rot of strawberries from greenhouse-grown plants in North Carolina, USA, root rot of roses in the Netherlands, and root rot of raspberry in Knoxfield, Australia, was identified. The main character of this organism is the production of paragynous antheridia with broad attachment to the oogonial wall. The morphology of the pathogen does not match that of any of the more than 85 described Phytophthora species. Phylogenetic analysis based on sequences of the internal transcribed spacer rDNA region (ITS1-5.8S-ITS2) of this taxon and those from other Phytophthora species from GenBank supports the conclusion that this organism is an unreported new species. In the phylogenetic tree with other reported Phytophthora species at the GenBank, the new species is more closely related to others in ITS clade 2 comprising semipapillate taxa including P. botryosa, P. citrophthora, P. colocasiae, P. meadii, P. citricola, P. inflata, P.tropicalis, P. capsici, Phytophthora sp. 'glovera' and P. multivesiculata. The most closely related species is P. multivesiculata isolated from Cymbidium orchid in the Netherlands. In this paper we describe the morphological characteristics and the phylogenetic relationships that support the description of this taxon as a new species Phytophthora bisheria sp. nov.}, number={1}, journal={MYCOLOGIA}, author={Abad, Z. Gloria and Abad, Jorge A. and Coffey, Michael D. and Oudemans, Peter V. and Man, Willem A. and Gruyter, Hans and Cunnington, James and Louws, Frank J.}, year={2008}, pages={99–110} }
 @article{leandro_guzman_ferguson_fernandez_louws_2007, title={Population dynamics of Trichoderma in fumigated and compost-amended soil and on strawberry roots}, volume={35}, ISSN={["1873-0272"]}, DOI={10.1016/j.apsoil.2006.04.008}, abstractNote={Effectiveness of Trichoderma strains for biocontrol of soilborne pathogens requires an improved understanding of soil and root ecology of this fungus. We compared the population dynamics of Trichoderma hamatum strain T382 (T382) and indigenous Trichoderma spp. in soil and on roots in different strawberry production systems. Strawberry transplants, either amended or not-amended with Trichoderma biocontrol strains, were planted in field soil left untreated or treated with soil fumigant, compost, and compost-amended with T382. Soil and root samples were taken between October and June of two production seasons (2002-03 and 2003-04), and Trichoderma populations were assessed by plating soil dilutions and root pieces onto selective medium. Identity of T382 was confirmed using strain-specific primers. T382 became established and maintained a stable population of 103 cfu/g soil throughout the growing season when added to field soil in amended compost, but T382 was rarely isolated from strawberry roots. Populations of indigenous Trichoderma spp. were up to 60-fold greater in fumigated soil than in any other soil treatment. Indigenous Trichoderma spp. were isolated from a greater proportion (20–50%) of roots in fumigated soil than from roots in the other treatments (0–20%). Transplant treatments did not significantly affect Trichoderma populations on roots or in soil during field production. This study showed that compost may be used as a substrate to establish and promote survival of Trichoderma in field soil, and illustrates how soil manipulation can affect population dynamics of indigenous Trichoderma spp. on roots and in soil.}, number={1}, journal={APPLIED SOIL ECOLOGY}, publisher={Elsevier BV}, author={Leandro, L. F. S. and Guzman, T. and Ferguson, L. M. and Fernandez, G. E. and Louws, F. J.}, year={2007}, month={Jan}, pages={237–246} }
 @article{leandro_ferguson_louws_fernandez_2007, title={Strawberry Growth and Productivity in Fumigated Compared to Compost-amended Production Systems}, volume={42}, DOI={10.21273/hortsci.42.2.227}, abstractNote={Strawberry (Fragaria ×ananassa Duchnesne) growth and productivity were compared in fumigated and nonfumigated production systems. Strawberry transplants grown in potting mix amended with Trichoderma hamatum (Bonord.) Bainier, strain T382, Trichoderma harzianum Rifai, strain T22, or untreated, were planted in field plots treated with compost, compost amended with T. hamatum strain T382, Telone-C35, or not treated. Plants were sampled throughout the growing season, and dry weights of roots, crowns, leaves, flowers and fruit, leaf area, and total and marketable yield were determined. Trichoderma amendments to the potting mix improved plant dry weight and leaf area of strawberry transplants in the first year and suppressed root rot incidence in the second year but did not affect plant growth or disease incidence once the plants were set in the field. Field plants in fumigated plots had greater root, leaf, and crown dry weights, leaf area, and yield compared with plants in the other soil treatments. We conclude that Trichoderma amendments (1) alone had little benefit to plug plant growth and (2) in combination with compost, had no benefit to strawberry plant growth in the field. The task remains to develop a reliable and sustainable strawberry production system that does not rely on chemical fumigants.}, number={2}, journal={HortScience}, publisher={American Society for Horticultural Science}, author={Leandro, Leonor F.S. and Ferguson, Lisa M. and Louws, Frank J. and Fernandez, Gina E.}, year={2007}, month={Apr}, pages={227–231} }
 @article{rademaker_norman_forster_louws_schultz_bruijn_2006, title={Classification and identification of Xanthomonas translucens isolates, including those pathogenic to ornamental asparagus}, volume={96}, ISSN={["1943-7684"]}, DOI={10.1094/PHYTO-96-0876}, abstractNote={ In order to confirm and refine the current classification scheme of Xanthomonas translucens and to identify novel strains from ornamental asparagus, a collection of field and reference strains was analyzed. Rep-polymerase chain reaction (PCR) genomic fingerprint profiles were generated from 33 isolates pathogenic to asparagus as well as 61 X. trans-lucens reference strains pathogenic to cereals and grasses. Amplified ribo-somal gene restriction analysis profiles were obtained from most of these and 29 additional Xanthomonas reference strains. Rep-PCR genomic fingerprint profiles of all strains were compared with those in a large Xanthomonas database using computer-assisted analysis. Rep-PCR ge-nomic fingerprinting facilitated the characterization and discrimination of X. translucens, including the pathovars arrhenatheri, graminis, phlei, phleipratensis, and poae, as well as a number of strains received as X. translucens pv. cerealis. Strains received as pathovars hordei, secalis, translucens, undulosa, and other cerealis strains were grouped in two subclusters that correspond to the recently redefined pathovars X. trans-lucens pvs. undulosa and translucens. All 33 novel isolates from ornamental asparagus (tree fern; Asparagus virgatus) were identified as X. translucens pv. undulosa. Moreover, a unique amplified small subunit ribosomal gene MspI/AluI restriction profile specific for all X. translucens strains tested, including those pathogenic to asparagus, allowed discrimination from all other Xanthomonas spp. Although phage tests were inconclusive, the classification of the asparagus strains within the X. translucens complex was supported by pathogenicity assays in which all the isolates from ornamental asparagus induced watersoaking on wheat. Surprisingly, several X. translucens reference strains affected asparagus tree fern as well. That the novel asparagus isolates belong to X. translucens pv. undulosa is extraordinary because all hosts of X. translucens pathovars described to date belong only to the families Gramineae and Poaceae, whereas asparagus belongs to the phylogenetically distant family Liliaceae. }, number={8}, journal={PHYTOPATHOLOGY}, author={Rademaker, J. L. W. and Norman, D. J. and Forster, R. L. and Louws, F. J. and Schultz, A. H. and Bruijn, F. J.}, year={2006}, month={Aug}, pages={876–884} }
 @article{cuppels_louws_ainsworth_2006, title={Development and evaluation of PCR-based diagnostic assays for the bacterial speck and bacterial spot pathogens of tomato}, volume={90}, ISSN={["1943-7692"]}, DOI={10.1094/PD-90-0451}, abstractNote={ Bacterial speck and bacterial spot lesions can easily be confused with each other and with those formed by other tomato pathogens. To facilitate disease diagnosis, we developed and evaluated polymerase chain reaction (PCR)-based lesion assays using crude DNA extracts and primer sets COR1/2 (bacterial speck) and BSX1/2 (bacterial spot). All 29 pathogenic Pseudomonas syringae pv. tomato strains tested produced a 689-bp amplicon with COR1/2; 28 of the 37 geographically diverse bacterial spot-causing xanthomonad (BSX) strains that were tested generated the 579-bp BSX1/2 amplicon. The detection limit with plant samples was 30 to 50 CFU/reaction. In a 6-year study, the COR1/2 PCR assay diverged from the culture-based classical assay for only 3 of 70 bacterial speck lesion samples collected from Ontario greenhouses and tomato fields; the BSX1/2 assay was positive for 112 of the 124 confirmed bacterial spot lesions sampled. The majority (66%) of the BSX strains isolated from these lesions belonged to group D; the 12 strains that were BSX1/2-negative belonged to group C. Group D strains produced a 425-bp PCR product with crude DNA extracts but a 579-bp product with purified DNA; the former was identical to the latter except that it was missing 150 bp from the middle of the 579-bp sequence. }, number={4}, journal={PLANT DISEASE}, publisher={Scientific Societies}, author={Cuppels, DA and Louws, FJ and Ainsworth, T}, year={2006}, month={Apr}, pages={451–458} }
 @article{development and evaluation of pcr-based diagnostic assays for the bacterial speck and bacterial spot pathogens of tomato (vol 90, pg 451, 2006)_2006, url={https://publons.com/wos-op/publon/56007366/}, journal={Plant Disease}, year={2006} }
 @article{sydorovych_safley_ferguson_poling_fernandez_brannen_monks_louws_2006, title={Economic evaluation of methyl bromide alternatives for the production of strawberries in the southeastern United States}, volume={16}, number={1}, journal={HortTechnology}, author={Sydorovych, O. and Safley, C. D. and Ferguson, L. M. and Poling, E. B. and Fernandez, G. E. and Brannen, P. A. and Monks, D. M. and Louws, F. J.}, year={2006}, pages={118–128} }
 @article{sanders_reyes_monks_jennings_louws_driver_2006, title={INFLUENCE OF COMPOST ON VEGETABLE CROP NUTRIENT MANAGEMENT}, volume={41}, DOI={10.21273/hortsci.41.3.508a}, abstractNote={Tomato, pepper and cucumber were grown for consecutive years using compost from two North Carolina cities (Lexington and Edenton) and McGill Composts (CMC) sources and CMC amended with Tracoderma 382. Treatments included compost with an untreated control and Telone C-35 (Telone) with and without additional fertilizer. The objective was to evaluate compost influence on yield and pest management. Results showed significant differences between treatments and among years. Cucumber and pepper had higher total and marketable yields in 2005 than in 2004. Although tomato yield was lower in 2005 than in 2004 it was evident that CMC+Telone had a higher marketable and total plant dry weight in both years. Two year data showed that combinations of treatments with CMC and Telone (Telone+fertilizer, CMC+Telone, CMC+T382) produced higher yield for tomato and cucumber. Composts from Lexington and Edenton produced more number 2 grade peppers, but treatments did not differ in total and marketable yield. In general compost treatments with or without amendments showed better results in crop yields than the control. Weed counts by species were determined on all plots. Pepper had the greatest number of weeds relative to cucumber and tomato. Organic amendments seem to increase the action of the compost source in several crops. Combination of treatments may depend on the particular crop.}, number={3}, journal={HortScience}, publisher={American Society for Horticultural Science}, author={Sanders, D.C. and Reyes, L.M. and Monks, D.W. and Jennings, K.M. and Louws, F.J. and Driver, J.G.}, year={2006}, month={Jun}, pages={508A–508} }
 @article{sanders_reyes_monks_jennings_louws_driver_2006, title={INFLUENCE OF COMPOST ON VEGETABLE CROP NUTRIENT MANAGEMENT}, volume={41}, DOI={10.21273/hortsci.41.3.509c}, abstractNote={Tomato, pepper, and cucumber were grown for consecutive years using compost from two North Carolina cities (Lexington and Edenton) and McGill Composts (CMC) sources and CMC amended with Tracoderma 382. Treatments included compost with an untreated control and Telone C-35 (Telone) with and without additional fertilizer. The objective was to evaluate compost influence on yield and pest management. Results showed significant differences between treatments and among years. Cucumber and pepper had higher total and marketable yields in 2005 than in 2004.}, number={3}, journal={HortScience}, publisher={American Society for Horticultural Science}, author={Sanders, D.C. and Reyes, L.M. and Monks, D.W. and Jennings, K.M. and Louws, F.J. and Driver, J.G.}, year={2006}, month={Jun}, pages={509C–509} }
 @article{tu_louws_creamer_mueller_brownie_fager_bell_hu_2006, title={Responses of soil microbial biomass and N availability to transition strategies from conventional to organic farming systems}, volume={113}, ISSN={["1873-2305"]}, DOI={10.1016/j.agee.2005.09.013}, abstractNote={Abstract Organic farming can enhance soil biodiversity, alleviate environmental concerns and improve food safety through eliminating the applications of synthetic chemicals. However, yield reduction due to nutrient limitation and pest incidence in the early stages of transition from conventional to organic systems is a major concern for organic farmers, and is thus a barrier to implementing the practice of organic farming. Therefore, identifying transition strategies that minimize yield loss is critical for facilitating the implementation of organic practices. Soil microorganisms play a dominant role in nutrient cycling and pest control in organic farming systems, and their responses to changes in soil management practices may critically impact crop growth and yield. Here we examined soil microbial biomass and N supply in response to several strategies for transitioning from conventional to organic farming systems in a long-term field experiment in Goldsboro, NC, USA. The transitional strategies included one fully organic strategy (ORG) and four reduced-input strategies (withdrawal of each or gradual reduction of major conventional inputs—synthetic fertilizers, pesticides (insecticides/fungicides), and herbicides), with a conventional practice (CNV) serving as a control. Microbial biomass and respiration rate were more sensitive to changes in soil management practices than total C and N. In the first 2 years, the ORG was most effective in enhancing soil microbial biomass C and N among the transition strategies, but was accompanied with high yield losses. By the third year, soil microbial biomass C and N in the reduced-input transition strategies were statistically significantly greater than those in the CNV (averaging 32 and 35% higher, respectively), although they were slightly lower than those in the ORG (averaging 13 and 17% lower, respectively). Soil microbial respiration rate and net N mineralization in all transitional systems were statistically significantly higher than those in the CNV (averagely 83 and 66% greater, respectively), with no differences among the various transition strategies. These findings suggest that the transitional strategies that partially or gradually reduce conventional inputs can serve as alternatives that could potentially minimize economic hardships as well as benefit microbial growth during the early stages of transition to organic farming systems.}, number={1-4}, journal={AGRICULTURE ECOSYSTEMS & ENVIRONMENT}, author={Tu, C and Louws, FJ and Creamer, NG and Mueller, JP and Brownie, C and Fager, K and Bell, M and Hu, SJ}, year={2006}, month={Apr}, pages={206–215} }
 @article{rademaker_louws_schultz_rossbach_vauterin_swings_bruijn_2005, title={A Comprehensive Species to Strain Taxonomic Framework forXanthomonas}, volume={95}, DOI={10.1094/phyto-95-1098}, abstractNote={ A comprehensive classification framework was developed that refines the current Xanthomonas classification scheme and provides a detailed assessment of Xanthomonas diversity at the species, subspecies, pathovar, and subpathovar levels. Polymerase chain reaction (PCR) using primers targeting the conserved repetitive sequences BOX, enterobacterial repetitive intergenic consensus (ERIC), and repetitive extragenic palindromic (REP) (rep-PCR) was used to generate genomic fingerprints of 339 Xanthomonas strains comprising 80 pathovars, 20 DNA homology groups, and a Stenotrophomonas maltophilia reference strain. Computer-assisted pattern analysis of the rep-PCR profiles permitted the clustering of strains into distinct groups, which correspond directly to the 20 DNA-DNA homology groups(genospecies) previously identified. Group 9 strains (X. axonopodis) were an exception and did not cluster together into a coherent group but comprised six subgroups. Over 160 strains not previously characterized by DNA-DNA hybridization analysis, or not previously classified, were assigned to specific genospecies based on the classification framework developed. The rep-PCR delineated subspecific groups within X. hortorum, X. arboricola, X. axonopodis, X. oryzae, X. campestris, and X. translucens. Numerous taxonomic issues with regard to the diversity, similarity, redundancy, or misnaming were resolved. This classification framework will enable the rapid identification and classification of new, novel, or unknown Xanthomonas strains that are pathogenic or are otherwise associated with plants. }, number={9}, journal={Phytopathology}, publisher={Scientific Societies}, author={Rademaker, J. L. W. and Louws, F. J. and Schultz, M. H. and Rossbach, U. and Vauterin, L. and Swings, J. and Bruijn, F. J.}, year={2005}, month={Sep}, pages={1098–1111} }
 @article{byrne_dianese_ji_campbell_cuppels_louws_miller_jones_wilson_2005, title={Biological control of bacterial spot of tomato under field conditions at several locations in North America}, volume={32}, ISSN={["1090-2112"]}, DOI={10.1016/j.biocontrol.2004.12.001}, abstractNote={Following the relatively successful biological control of bacterial speck of tomato under field conditions at several locations (Phytopathology 92 (2002) 1284), similar selection and testing strategies were employed in an effort to isolate an effective biological control agent for bacterial spot of tomato. Fifty potential biological control agents were isolated from tomato foliage in Alabama (AL) and Florida (FL) and tested under greenhouse conditions in AL for the ability to reduce the foliar severity of bacterial spot of tomato (Lycopersicon esculentum), which is caused by either Xanthomonas campestris pv. vesicatoria or Xanthomonas vesicatoria. Three pseudomonads that provided protection against bacterial speck also were included in the tests. The strains which were most efficacious (i.e., high mean percentage reduction) and consistent (i.e., low standard deviation) in reducing bacterial spot severity in repeated greenhouse experiments were selected for field experiments conducted over the period 1996–1998. Among these strains were Cellulomonas turbata BT1, which provided the highest mean reduction in disease severity [45.2% (SD = 21.0)], and Pseudomonas syringae Cit7 [36.4% (SD = 12.2)], which was the most consistent. Field experiments were conducted in Shorter, AL; Bradenton and Sanford, FL; Clinton, North Carolina; Wooster, Ohio; and London, Ontario, Canada. The highest mean reductions in severity of bacterial spot on foliage, averaged across all locations, were provided by P. syringae Cit7 [28.9% (SD = 11.6)] and Pseudomonas putida B56 [23.1% (SD = 7.4)]. The efficacy and consistency of P. syringae Cit7 against bacterial spot were very similar to those achieved against bacterial speck [28.3% (SD = 12.7)] (Phytopathology 92 (2002) 1284). Unfortunately, neither the bacterial strains nor the standard copper bactericides consistently reduced disease incidence on fruit.}, number={3}, journal={BIOLOGICAL CONTROL}, author={Byrne, JM and Dianese, AC and Ji, P and Campbell, HL and Cuppels, DA and Louws, FJ and Miller, SA and Jones, JB and Wilson, M}, year={2005}, month={Mar}, pages={408–418} }
 @article{gent_al-saadi_gabriel_louws_ishimaru_schwartz_2005, title={Pathogenic and genetic relatedness among Xanthomonas axonopodis pv. allii and other pathovars of X-axonopodis}, volume={95}, ISSN={["1943-7684"]}, DOI={10.1094/PHYTO-95-0918}, abstractNote={ Xanthomonas axonopodis pv. allii is phenotypically and genetically diverse and its relationship to other X. axonopodis pathovars within DNA homology group 9.2 is unknown. In growth chamber experiments, disease symptoms were produced on onion only by inoculation with X. axonopodis pv. allii. Citrus bacterial spot symptoms were induced by X. axonopodis pvs. alfalfae, itrumelo, and allii on Duncan grapefruit and key lime. X. axonopodis pv. allii multiplication and persistence in Duncan grapefruit were equal to those of an aggressive strain of X. axonopodis pv. citrumelo, but populations of X. axonopodis pvs. alfalfae, betlicola, citrumelo, phaseoli, and vesicatoria were 1.3 to 4.0 log units less than X. axonopodis pv. allii in onion. Genomic fingerprinting by repetitive sequence- based polymerase chain reaction demonstrated that X. axonopodis pvs. allii, alfalfae, and citrumelo are distinct from other Xanthomonas species and X. axonopodis pathovars, but these pathovars were indistinguishable from each other. Three genotype groups were apparent among DNA homology group 9.2 strains, and generally correspond to the aggressiveness and genotype groups previously described for X. axonopodis pv. citrumelo. X. axonopodis pvs. allii, alfalfae, and citrumelo appear to have recently diverged from a common ancestral strain. }, number={8}, journal={PHYTOPATHOLOGY}, publisher={Scientific Societies}, author={Gent, DH and Al-Saadi, A and Gabriel, DW and Louws, FJ and Ishimaru, CA and Schwartz, HF}, year={2005}, month={Aug}, pages={918–925} }
 @article{zhang_rui_tu_diab_louws_mueller_creamer_bell_wagger_hu_2005, title={Responses of soil microbial community structure and diversity to agricultural deintensification}, volume={15}, number={4}, journal={Pedosphere}, author={Zhang, W. J. and Rui, W. Y. and Tu, C. and Diab, H. G. and Louws, F. J. and Mueller, J. P. and Creamer, N. and Bell, M. and Wagger, M. G. and Hu, S.}, year={2005}, pages={440–447} }
 @article{sanders_reyes_monks_louws_driver_2005, title={Use of Compost as an Alternative to Methyl Bromide for Vegetables}, volume={40}, DOI={10.21273/hortsci.40.4.1110e}, abstractNote={We evaluated the influence of three compost sources and compost amended with T382 with fumigant Telone C-35 and various combinations of compost and Telone C-35 on the yield and pest management of cucumber, pepper, tomato, collard, southern pea, and summer squash in a multicrop rotational system. In the first year, there were few differences between the compost treatments and Telone C-35, but all treatments resulted in more yield than the control. In the second year, all compost treatments and/or Telone C-35 improved total and marketable yield of cucumber, pepper, tomato, southern pea, and summer squash. Furthermore, in the second year, Telone C-35 treat-ments produced more yield than some of the compost treatments in tomatoes. Combining Telone C-35 with compost did not differ from either treatment alone. Nematode and disease assessments were not consistent and will be discussed in further detail.}, number={4}, journal={HortScience}, publisher={American Society for Horticultural Science}, author={Sanders, Doug and Reyes, Luz M. and Monks, David and Louws, Frank and Driver, James}, year={2005}, month={Jul}, pages={1110E–1111} }
 @article{leandro_ferguson_fernandez_louws_2004, title={Evaluation of Trichoderma strains as biocontrol tools for integrated management of strawberry root rot}, ISBN={9290671708}, journal={Proceedings of a meeting of the WGs : management of plant diseases and arthropod pests by BCAs and their integration in agriculture systems at S. Michele all'Adige, Trentino, Italy, 9-13 June 2004}, publisher={Dijon, France : International Organization for Biological and Integrated Control of Noxious Animals and Plants, West Palaearctic Regional Section}, author={Leandro, L. and Ferguson, L. and Fernandez, G. and Louws, F.}, editor={Y. Elad, I. Pertot and Enkegaard, A.Editors}, year={2004} }
 @article{rippy_peet_louws_nelson_orr_sorensen_2004, title={Plant development and harvest yields of greenhouse tomatoes in six organic growing systems}, volume={39}, number={2}, journal={HortScience}, author={Rippy, J. F. M. and Peet, M. M. and Louws, F. J. and Nelson, P. V. and Orr, D. B. and Sorensen, K. A.}, year={2004}, pages={223–229} }
 @article{gent_schwartz_ishimaru_louws_cramer_lawrence_2004, title={Polyphasic characterization of Xanthomonas strains from onion}, volume={94}, ISSN={["1943-7684"]}, DOI={10.1094/PHYTO.2004.94.2.184}, abstractNote={ Xanthomonas leaf blight has become an increasingly important disease of onion, but the diversity among Xanthomonas strains isolated from onion is unknown, as is their relationship to other species and pathovars of Xanthomonas. Forty-nine Xanthomonas strains isolated from onion over 27 years from 10 diverse geographic regions were characterized by pathogenicity to onion and dry bean, fatty acid profiles, substrate utilization patterns (Biolog), bactericide resistance, repetitive sequence-based polymerase chain reaction fingerprinting, rDNA internally transcribed spacer (ITS) region, and hrp b6 gene sequencing. Multiplication of onion Xanthomonas strain R-O177 was not different from X. axonopodis pv. phaseoli in dry bean, but typical common bacterial blight disease symptoms were absent in dry bean. Populations from each geographical region were uniformly sensitive to 100 μg of CuSO4, 100 μg of ZnSO4, and 100 μg of streptomycin sulfate per ml. Biolog substrate utilization and fatty acid profiles revealed close phenoltypic relatedness between onion strains of Xanthomonas and X. axonopodis pv. dieffenbachiae (57% of strains) and X. arboricola pv. poinsettiicola (37% of strains), respectively. A logistic regression model based on fatty acid composition and substrate utilization classified 69% of strains into their geographical region of origin. Sequencing of a portion of the hrp B6 gene from 24 strains and ITS region from 25 strains revealed greater than 97% sequence similarity among strains. DNA fingerprinting revealed five genotype groups within onion strains of Xanthomonas and a high degree of genetic diversity among geographical regions of origin. Based on pathogenicity to onion, carbon substrate utilization, fatty acid profiles, rDNA genetic diversity, and genomic fingerprints, we conclude that the strains examined in this study are pathovar X. axonopodis pv. allii. Implications of genetic and phenotypic diversity within X. axonopodis pv. allii are discussed in relation to an integrated pest management program. }, number={2}, journal={PHYTOPATHOLOGY}, publisher={Scientific Societies}, author={Gent, DH and Schwartz, HF and Ishimaru, CA and Louws, FJ and Cramer, RA and Lawrence, CB}, year={2004}, month={Feb}, pages={184–195} }
 @article{mueller_barbercheck_bell_brownie_creamer_hitt_hu_king_linker_louws_et al._2002, title={Development and implementation of a long-term agricultural systems study: Challenges and opportunities}, volume={12}, number={3}, journal={HortTechnology}, author={Mueller, J. P. and Barbercheck, M. E. and Bell, M. and Brownie, C. and Creamer, N. G. and Hitt, A. and Hu, S. and King, L. and Linker, H. M. and Louws, F. J. and et al.}, year={2002}, pages={362–368} }
 @article{butler_fernandez_louws_2002, title={Strawberry plant growth parameters and yield among transplants of different types and from different geographic sources, grown in a plasticulture system}, volume={12}, number={1}, journal={HortTechnology}, author={Butler, L. M. and Fernandez, G. E. and Louws, F. J.}, year={2002}, pages={100–103} }
 @article{staman_blum_louws_robertson_2001, title={Can simultaneous inhibition of seedling growth and stimulation of rhizosphere bacterial populations provide evidence for phytotoxin transfer from plant residues in the bulk soil to the rhizosphere of sensitive species?}, volume={27}, ISSN={["1573-1561"]}, DOI={10.1023/A:1010362221390}, abstractNote={In order to demonstrate that allelopathic interactions are occurring, one must, among other things, demonstrate that putative phytotoxins move from plant residues on or in the soil, the source, through the bulk soil to the root surface, a sink, by way of the rhizosphere. We hypothesized that the incorporation of phytotoxic plant residues into the soil would result in a simultaneous inhibition of seedling growth and a stimulation of the rhizosphere bacterial community that could utilize the putative phytotoxins as a sole carbon source. If true and consistently expressed, such as relationship would provide a means of establishing the transfer of phytotoxins from residue in the soil to the rhizosphere of a sensitive species under field conditions. Presently, direct evidence for such transfer is lacking. To test this hypothesis, cucumber seedlings were grown in soil containing various concentrations of wheat or sunflower tissue. Both tissue types contain phenolic acids, which have been implicated as allelopathic phytotoxins. The level of phytotoxicity of the plant tissues was determined by the inhibition of pigweed seedling emergence and cucumber seedling leaf area expansion. The stimulation of cucumber seedling rhizosphere bacterial communities was determined by the plate dilution frequency technique using a medium containing phenolic acids as the sole carbon source. When sunflower tissue was incorporated into autoclaved (to reduce the initial microbial populations) soil, a simultaneous inhibition of cucumber seedling growth and stimulation of the community of phenolic acid utilizing rhizosphere bacteria occurred. Thus, it was possible to observe simultaneous inhibition of cucumber seedlings and stimulation of phenolic acid utilizing rhizosphere bacteria, and therefore provide indirect evidence of phenolic acid transfer from plant residues in the soil to the root surface. However, the simultaneous responses were not sufficiently consistent to be used as a field screening tool but were dependent upon the levels of phenolic acids and the bulk soil and rhizosphere microbial populations present in the soil. It is possible that this screening procedure may be useful for phytotoxins that are more unique than phenolic acids.}, number={4}, journal={JOURNAL OF CHEMICAL ECOLOGY}, author={Staman, K and Blum, U and Louws, F and Robertson, D}, year={2001}, month={Apr}, pages={807–829} }
 @article{louws_wilson_campbell_cuppels_jones_shoemaker_sahin_miller_2001, title={Field control of bacterial spot and bacterial speck of tomato using a plant activator}, volume={85}, ISSN={["0191-2917"]}, DOI={10.1094/PDIS.2001.85.5.481}, abstractNote={ Acibenzolar-S-methyl (CGA 245704 or Actigard 50WG) is a plant activator that induces systemic acquired resistance (SAR) in many different crops to a number of pathogens. Acibenzolar-S-methyl was evaluated for management of bacterial spot (Xanthomonas axonopodis pv. vesicatoria) and bacterial speck (Pseudomonas syringae pv. tomato) of tomato in 15 and 7 field experiments, respectively. Experiments were conducted over a 4-year period in Florida, Alabama, North Carolina, Ohio, and Ontario using local production systems. Applied at 35 g a.i. ha-1, acibenzolar-S-methyl reduced foliar disease severity in 14 of the 15 bacterial spot and all 7 bacterial speck experiments. Disease control was similar or superior to that obtained using a standard copper bactericide program. Acibenzolar-S-methyl also reduced bacterial fruit spot and speck incidence. Tomato yield was not affected by using the plant activator in the field when complemented with fungicides to manage foliar fungal diseases, but tomato transplant dry weight was negatively impacted. X. axonopodis pv. vesicatoria population densities on greenhouse-grown tomato transplants were reduced by acibenzolar-S-methyl treatment. Bacterial speck and spot population densities on leaves of field-grown plants were not dramatically affected. Acibenzolar-S-methyl can be integrated as a viable alternative to copper-based bactericides for field management of bacterial spot and speck, particularly where copper-resistant populations predominate. }, number={5}, journal={PLANT DISEASE}, author={Louws, FJ and Wilson, M and Campbell, HL and Cuppels, DA and Jones, JB and Shoemaker, PB and Sahin, F and Miller, SA}, year={2001}, month={May}, pages={481–488} }
 @article{louws_ritchie_shoemaker_2001, title={Genetic Diversity of Selected Bacterial Populations in North Carolina}, DOI={10.1007/978-94-010-0003-1_24}, journal={Plant Pathogenic Bacteria}, publisher={Springer Netherlands}, author={Louws, F. J. and Ritchie, D. F. and Shoemaker, P. B.}, year={2001}, pages={124–127} }
 @article{fernandez_butler_louws_2001, title={Strawberry Growth and Development in an Annual Plasticulture System}, volume={36}, ISSN={0018-5345 2327-9834}, url={http://dx.doi.org/10.21273/hortsci.36.7.1219}, DOI={10.21273/hortsci.36.7.1219}, abstractNote={The growth and development of three strawberry cultivars commonly grown in a plasticulture system were documented. Strawberry plants were harvested monthly and divided by roots, crown, leaves, flowers, and fruit and then dried in an oven. The dry matter production and resource allocation proceeded along a predictable pattern of development. The establishment phase was characterized by an active period of growth of root, crown and leaves in the fall. Through the winter, the plants underwent slow growth, ending in a transition period in the late winter/early spring when resources were allocated to both vegetative and reproductive growth. In the spring, all plant parts received significantly increased allocation of, or redistribution of, resources. Cultivars of California origin, `Chandler' and `Camarosa', displayed similar trends in yield, dry matter production, seasonal resource allocation, and growth analysis variables throughout the season. `Sweet Charlie', a cultivar from Florida, showed lower dry matter accumulation and relative growth rate in the spring, higher harvest index and lower yield than the California cultivars.}, number={7}, journal={HortScience}, publisher={American Society for Horticultural Science}, author={Fernandez, Gina E. and Butler, Laura M. and Louws, Frank J.}, year={2001}, month={Dec}, pages={1219–1223} }
 @article{creamer_baldwin_louws_2000, title={A Training Series for Cooperative Extension Agents on Organic Farming Systems}, volume={10}, DOI={10.21273/horttech.10.4.675}, abstractNote={More than 50 agents participated in a series of workshops that were offered as in-service training and as a graduate level North Carolina State University (NCSU) course worth four credits. The Organic Unit at the Center for Environmental Farming Systems (CEFS), a 100-acre (40-ha) facility dedicated to research and education in organic farming systems, served as a home base for training activities. These training activities consisted of lectures, hands-on demonstrations, group discussions, field trips, and class exercises. Two unique features of the workshops were the interdisciplinary, team teaching approach and the emphasis on integration of information about interactions among production practices. This well-received, successful training program will serve as a model for future extension training. A training manual, slide sets, extension publications, and an organic farming web site are being created to provide agents with the resource materials they need to conduct county-based educational programming in organic production systems and enterprises. The model for extension training presented in this report is an effective means for engaging county agents in continuing education and professional development. Interdisciplinary teaching teams allow for a full, integrated treatment of subject matter and present a whole systems perspective to agents. Regularly scheduled, intensive sessions that accommodate busy calendars and utilize time efficiently provide a strong incentive for regular attendance. Awarding graduate level university credit hours for completion of required course work attracts and retains prospective student and agents. Encouragement of active participation by agents through hands-on field activities, open discussion of issues that impact agricultural and rural life, and field trips to view concepts presented in a real world context ensure that educational goals are fulfilled and that active learning takes place. This model should be used in future extension training programs.}, number={4}, journal={HortTechnology}, publisher={American Society for Horticultural Science}, author={Creamer, N.G. and Baldwin, K.R. and Louws, F.J.}, year={2000}, month={Jan}, pages={675–681} }
 @article{rademaker_hoste_louws_kersters_swings_vauterin_vauterin_bruijn_2000, title={Comparison of AFLP and rep-PCR genomic fingerprinting with DNA-DNA homology studies: Xanthomonas as a model system}, volume={50}, ISSN={["1466-5026"]}, DOI={10.1099/00207713-50-2-665}, abstractNote={The genus Xanthomonas contains a large number of strains, which have been characterized by a variety of phenotypic and genotypic classification methods. The Xanthomonas collection constitutes one of the largest groups of bacteria that have been characterized phylogenetically by DNA-DNA homology studies and genomic fingerprinting. Presently, a total genomic DNA-DNA homology value of 70% represents an internationally accepted criterion to define bacterial species levels. However, the complexity of DNA-DNA reassociation kinetics methods precludes the rapid analysis of large numbers of bacterial isolates, which is imperative for molecular microbial diversity studies. Therefore, the aim of this study was to compare more facile PCR-based genomic fingerprinting techniques, such as repetitive-sequence-based (rep)-PCR and AFLP genomic fingerprinting, to DNA-DNA hybridization studies. Using three different primer sets, rep-PCR genomic fingerprint patterns were generated for 178 Xanthomonas strains, belonging to all 20 previously defined DNA-DNA homology groups, and one Stenotrophomonas maltophilia strain. In addition, AFLP genomic fingerprints were produced for a subset of 80 Xanthomonas strains belonging to the 20 DNA-DNA homology groups and for the S. maltophilia strain. Similarity values derived from rep-PCR- and AFLP-generated fingerprinting analyses were calculated and used to determine the correlation between rep-PCR- or AFLP-derived relationships and DNA-DNA homology values. A high correlation was observed, suggesting that genomic fingerprinting techniques truly reveal genotypic and phylogenetic relationships of organisms. On the basis of these studies, we propose that genomic fingerprinting techniques such as rep-PCR and AFLP can be used as rapid, highly discriminatory screening techniques to determine the taxonomic diversity and phylogenetic structure of bacterial populations.}, number={2000 Mar.}, journal={INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY}, author={Rademaker, JLW and Hoste, B and Louws, FJ and Kersters, K and Swings, J and Vauterin, L and Vauterin, P and Bruijn, FJ}, year={2000}, month={Mar}, pages={665–677} }
 @article{creamer_baldwin_louws_1999, title={642 A Training Series in Organic Farming Systems}, volume={34}, DOI={10.21273/hortsci.34.3.558c}, abstractNote={Consumer demand for organically produced food and the desire by many farmers to eliminate chemical fertilizers and pesticides is increasing the need for research and educational programs to support organic farmers. To date, the land-grant universities and the cooperative extension service have been viewed by organic farmers as unresponsive to this need. The primary reason for the unresponsiveness has been inadequate training and resource materials available to extension agents. In 1998, we conducted an intensive training for agriculture agents in North Carolina. Funding was provided by the USDA SARE Professional Development Program. More than 50 agents participated in a series of workshops that were offered together as a graduate course worth four NCSU credits. Much of the training was conducted on the Organic Unit at The Center for Environmental Farming Systems (CEFS), a 100-acre facility dedicated to research and education in organic farming systems. The hands-on training consisted of lectures, demonstrations, field trips, and class exercises. The topic areas included soil biology/ecology; crop rotation; organic nutrient management; composting; cover crop management; organic weed, insect, and disease management; appropriate tillage practices; organic greenhouse management; marketing organic produce; integrating animals into organic crop production systems; delivery systems for disseminating information to organic producers, and; social and community development aspects of sustainable agriculture. Unique features of the workshops were the interdisciplinary approach to teaching them, and the integration of information about interactions between production factors. The training was very well-received and will serve as a model for future extension programming. A training manual, slide sets, extension publications, and a Web site are being created to further support agents as they conduct programming in their own counties.}, number={3}, journal={HortScience}, publisher={American Society for Horticultural Science}, author={Creamer, N.G. and Baldwin, K.R. and Louws, F.J.}, year={1999}, month={Jun}, pages={558C–558} }
 @article{tuang_rademaker_alocilja_louws_bruijn_1999, title={Identification of bacterial rep-PCR genomic fingerprints using a backpropagation neural network}, volume={177}, DOI={10.1111/j.1574-6968.1999.tb13740.x}, abstractNote={A backpropagation neural network (BPN) was used to identify bacterial plant pathogens based on their genomic fingerprints. Genomic fingerprint data, comprised of complex DNA band patterns generated using BOX, enterobacterial repetitive intergenic consensus (ERIC) and repetitive extragenic palindromic (REP)-primers (rep-PCR), were used to train three independent BPNs. 10 Strains of the genus Xanthomonas, each with a characteristic host plant range, were identified correctly using the three trained BPNs. When tested with fingerprints of bacterial strains not present in the training sets, the rejection rate was 100%, using the three BPN classifiers combined. Thus, BPN protocols can be employed to generate a powerful computer-based system for the identification of pathogenic bacteria in the genus Xanthomonas.}, number={2}, journal={FEMS Microbiology Letters}, publisher={Oxford University Press (OUP)}, author={Tuang, Fei Ni and Rademaker, Jan L.W. and Alocilja, Evangelyn C. and Louws, Frank J. and Bruijn, Frans J.}, year={1999}, month={Aug}, pages={249–256} }
 @article{bouzar_jones_stall_louws_schneider_rademaker_bruijn_jackson_1999, title={Multiphasic analysis of xanthomonads causing bacterial spot disease on tomato and pepper in the Caribbean and Central America: Evidence for common lineages within and between countries}, volume={89}, ISSN={["0031-949X"]}, DOI={10.1094/PHYTO.1999.89.4.328}, abstractNote={Four hundred thirty-three xanthomonad strains isolated from tomato or pepper plants from 32 different fields in four Caribbean and Central American countries were screened for the ability to hydrolyze starch and sodium polypectate and for resistance to copper and streptomycin. Of these, 95 representative strains were further characterized by various phnetic tests, and 63 of these strains were then analyzed by genomic fingerprinting. Most of the strains (>90%) were tolerant to copper. However, there was much more variability in sensitivity to streptomycin. All strains in Guadeloupe and 93% of the strains in Barbados were sensitive to streptomycin. The majority of strains were typical Xanthomonas campestris pv. vesicatoria group A strains. In Barbados, however, a unique group of strains was identified that was serologically similar to group A strains but was amylolytic. These strains were designated A1. The occurrence of X. campestris pv. vesicatoria group B strains in Central America was found to be limited to two fields in Costa Rica and one in Guatemala. No group B strains were identified in the Caribbean, in contrast to common occurrence in the central United States and in South America. T3 strains were not found in this study, despite the recent increase of such strains in Florida and Mexico. Unique strains from Costa Rica belonging to the X. gardneri group were identified. Little linkage was found among phenotypic and rep-polymerase chain reaction (rep-PCR) genomic fingerprinting profiles of the pathogens except at the species/pathovar level; strains displaying virtually identical fingerprint profiles were found to correspond to distinct races and vice versa. The rep-PCR genomic fingerprinting analyses suggest that certain lineages may have evolved or predominated in specific regions or specific countries.}, number={4}, journal={PHYTOPATHOLOGY}, author={Bouzar, H and Jones, JB and Stall, RE and Louws, FJ and Schneider, M and Rademaker, JLW and Bruijn, FJ and Jackson, LE}, year={1999}, month={Apr}, pages={328–335} }
 @book{louws_holmes_ristaino_1999, title={Phytophthora blight of peppers and cucurbits}, journal={Vegetable disease information note, Jan. 1999}, author={Louws, F. and Holmes, G. and Ristaino, J.}, year={1999} }
 @misc{louws_rademaker_bruijn_1999, title={The three Ds of PCR-based genomic analysis of phytobacteria: Diversity, detection, and disease diagnosis}, volume={37}, ISSN={["1545-2107"]}, DOI={10.1146/annurev.phyto.37.1.81}, abstractNote={ ▪ Abstract  The advent of molecular biology in general and the polymerase chain reaction in particular have greatly facilitated genomic analyses of microorganisms, provide enhanced capability to characterize and classify strains, and facilitate research to assess the genetic diversity of populations. The diversity of large populations can be assessed in a relatively efficient manner using rep-PCR-, AFLP-, and AP-PCR/RAPD-based genomic fingerprinting methods, especially when combined with computer-assisted pattern analysis. Genetic diversity maps provide a framework to understand the taxonomy, population structure, and dynamics of phytobacteria and provide a high-resolution framework to devise sensitive, specific, and rapid methods for pathogen detection, plant disease diagnosis, as well as management of disease risk. A variety of PCR-based fingerprinting protocols such as rDNA-based PCR, ITS-PCR, ARDRA, T-RFLPs, and tRNA-PCR have been devised, and numerous innovative approaches using specific primers have been adopted to enhance both the detection and identification of phytobacteria. PCR-based protocols, combined with computer-based analysis, have provided novel fundamental knowledge of the ecology and population dynamics of bacterial pathogens, and present exciting new opportunities for basic and applied studies in plant pathology. }, number={1}, journal={ANNUAL REVIEW OF PHYTOPATHOLOGY}, publisher={Annual Reviews}, author={Louws, FJ and Rademaker, JLW and Bruijn, FJ}, year={1999}, pages={81–125} }
 @article{carver_fernandez_louws_1998, title={Phenological Aspects of Strawberry Growth Influencing Gray Mold Development in Annual Systems}, volume={33}, DOI={10.21273/hortsci.33.3.538c}, abstractNote={Strawberry (Fragaria xananassa) plant phenology was evaluated at two sites in North Carolina in order to assess the relationship of plant growth and the development of gray mold fruit rot (Botrytis cinerea). Site 1 consisted of three cultivars: Camarosa (CA), Chandler (CH), and Sweet Charlie (SC) from a single nursery; site 2 consisted of cultivar CH obtained from three distinct sources. Weekly records were kept of leaf senescence, leaf emergence, flowering, and fruit set, as well as a monthly whole-plant analysis. Leaf senescence and emergence was uniform for all treatments, with >90% of transplant foliage senescing between November and December. Analysis of leaf area and plant weights reveal an increase in dry mass beginning in February and continuing through April. Although first bloom appeared in December, primary floral development occurred in late February for cultivar SC and in March for cultivars CA and CH, with blooms continuing through late May. Marketable yield was lower in cultivar SC throughout harvest, with the exception of early fruit development in March. Non-marketable yield varied, with increases in gray mold following periods of heavy rainfall. Statistical analysis of all data shows no consistent differences in plant growth or disease among treatments. Analysis of foliage revealed latent infections on transplants as the primary source of gray mold inoculum. Patterns of plant growth and corresponding disease development found in this study provide tools necessary for phenology-based control practices for the integrated management of gray mold.}, number={3}, journal={HortScience}, publisher={American Society for Horticultural Science}, author={Carver, L.M. Butler and Fernandez, G.E. and Louws, F.J.}, year={1998}, month={Jun}, pages={538c–538} }
 @article{louws_1996, title={Impact of Reduced Fungicide and Tillage on Foliar Blight, Fruit Rot, and Yield of Processing Tomatoes}, volume={80}, DOI={10.1094/pd-80-1251}, abstractNote={The effect of reduced tillage, soil-surface crop residue maintenance, and reduced fungicide input on processing tomato yield and disease incidence was studied in 1990 to 1992. Fall-seeded rye was desiccated in strips in early spring; the remainder, after 1.2 m of growth. Strips were zone tilled (ZT) 35 cm deep with no soil inversion. The ZT system permitted desiccated interrow rye residue to persist throughout the summer, providing approximately 90% cover of the soil surface. Tomatoes were transplanted into the prepared strips. The ZT system did not affect marketable yield or percent fruit with mold (1991 to 1992); but it decreased (1990), increased (1991), and did not affect (1992) defoliation caused by early blight (EB) compared to a conventional tillage production system using a moldboard plow, disk, or both. The fungicide, Bravo 720 (chlorothalonil), was applied as follows: none, weekly, or a full or reduced rate at intervals according to the disease forecasting model, TOM-CAST. Fungicide treatment did not enhance marketable yield compared to that of the unsprayed treatment. TOM-CAST-based treatments did not consistently provide control of defoliation compared to that in plots sprayed weekly. However, compared to weekly sprays, select forecast-generated spray schedules required 45 to 80% fewer applications to limit fruit mold incidence caused by Alternaria solani (EB), Colletotrichum coccodes (anthracnose), and Rhizoctonia solani (soil rot). Conservation tillage practices, soil-surface residue maintenance, and reduced fungicide input were integrated without compromising yield and management of disease, affording advantages of sustained farmland productivity.}, number={11}, journal={Plant Disease}, publisher={Scientific Societies}, author={Louws, Frank J.}, year={1996}, pages={1251} }
 @article{louws_1995, title={Differentiation of Genomic Structure by rep-PCR Fingerprinting to Rapidly ClassifyXanthomonas campestrispv.vesicatoria}, volume={85}, DOI={10.1094/phyto-85-528}, abstractNote={DNA primers corresponding to repetitive extragenic sequences (repetitive extragenic palindromic [REP], enterobacterial repetitive intergenic consensus [ERIC], and BOX element [BOXIA] sequences) and polymerase chain reaction (rep-PCR) were used to generate complex fingerprint patterns that identified four distinct genotypes among strains classified as Xanthomonas campestris pv. vesicatoria. After agarose gel electrophoresis, these genotypes were easily differentiated from each other by comparing the migration rates of 60 or more bands generated with rep-PCR. Representative strains of each genotype were pathogenic to tomato and/or pepper. We performed rep-PCR on numerous strains that have been included in previous studies, and our observations using the simple, rapid procedure of rep-PCR were consistent with the polyphasic approaches published by others. The majority of strains belonged to two previously described groups, A and B. Group A strains originated from tomato or pepper. Most of these strains proved to be negative in starch hydrolysis and pectolytic activity tests. All group A strains were relatively homogeneous with regard to their rep-PCR fingerprint patterns. Group B strains originated primarily from tomato and were positive for starch hydrolysis and pectolytic activity. Numerous rep-PCR fingerprint polymorphisms distinguished six patterns or lineages in group B. Group B strains comprised an important component of the tomato spot complex in the Northcentral tomato production region of North America. Three strains comprised two additional genotypes and were clear outliers compared to strains classified as group A or B. Interestingly, based on rep-PCR genomic fingerprint patterns, two of the nongroup A/B strains shared numerous bands of similar mobility with strains pathogenic for cabbage, classified as X. c. pv. campestris, suggesting that these two solanaceous strains are closely related to the cabbage pathogen}, number={5}, journal={Phytopathology}, publisher={Scientific Societies}, author={Louws, Frank J.}, year={1995}, pages={528} }
 @article{cohen_dombrovsky_louws, title={Grafting as agrotechnology for reducing disease damage.}, DOI={10.1079/9781780648972.0155}, abstractNote={Louws et al. (2010) summarized concurrent literature on the use of grafting technology to manage diseases (fungal, bacterial and viral), pests (including nematodes) and weeds in vegetable production, and provided up-to-date information on disease cycles, complementary disease-management practices, and the effects of rootstocks on controlling different diseases of cucurbits and solanaceous crops. This chapter emphasizes additional plant-pathology-associated aspects of critical importance to long-term success in grafting systems. Grafting of vegetables has expanded in most vegetable production regions of the world and provides a critical integrated pest management (IPM) tool to manage soilborne diseases. In addition to the direct effect that the rootstock confers on reducing disease incidence and severity, the grafting system introduces many complexities and opportunities related to disease management. Critical factors include considerations at each phase of production including seed health, management of diseases in the nursery, selection of the best genetics, unforeseen surprises, and an understanding and exploitation of mechanisms of resistance to limit disease severity. As the science and practice of IPM move forward, complemented with advances in genomics, an enhanced understanding of vegetable physiology and optimization of scion-rootstock interactions, grafting will become a more efficacious and precise tool to manage a large number of soilborne diseases of vegetables.}, journal={Vegetable grafting: principles and practices}, publisher={CABI}, author={Cohen, R. and Dombrovsky, A. and Louws, F. J.}, pages={155–170} }