@article{cochran_quesada-ocampo_kerns_thiessen_2024, title={<i>Phytophthora nicotianae</i>: A Quick Diagnostic Guide for Black Shank of Tobacco}, volume={5}, ISSN={["1535-1025"]}, url={https://doi.org/10.1094/PHP-10-23-0085-DG}, DOI={10.1094/PHP-10-23-0085-DG}, abstractNote={Phytophthora nicotianae is an oomycete pathogen that causes black shank of tobacco and is a major threat to tobacco production worldwide. P. nicotianae has been reported on 255 plant genera. Tobacco roots and crowns are the primary areas for disease symptoms but lower canopy leaf lesions can arise following initial infection. P. nicotianae can be isolated with semi-selective media from symptomatic tissue, contaminated water, and soil samples. The objective of this diagnostic guide is to provide a collection of current descriptions and methods for the symptomology, isolation, storage, and identification of P. nicotianae.}, journal={PLANT HEALTH PROGRESS}, author={Cochran, Sarah and Quesada-Ocampo, Lina M. and Kerns, James P. and Thiessen, Lindsey D.}, year={2024}, month={May} }
 @article{xu_knight_boone_saleem_finley_gauthier_ayariga_akinrinlola_pulkoski_britt_et al._2024, title={Influence of Fungicide Application on Rhizosphere Microbiota Structure and Microbial Secreted Enzymes in Diverse Cannabinoid-Rich Hemp Cultivars}, volume={25}, ISSN={["1422-0067"]}, DOI={10.3390/ijms25115892}, abstractNote={Microbes and enzymes play essential roles in soil and plant rhizosphere ecosystem functioning. However, fungicides and plant root secretions may impact the diversity and abundance of microbiota structure and enzymatic activities in the plant rhizosphere. In this study, we analyzed soil samples from the rhizosphere of four cannabinoid-rich hemp (Cannabis sativa) cultivars (Otto II, BaOx, Cherry Citrus, and Wife) subjected to three different treatments (natural infection, fungal inoculation, and fungicide treatment). DNA was extracted from the soil samples, 16S rDNA was sequenced, and data were analyzed for diversity and abundance among different fungicide treatments and hemp cultivars. Fungicide treatment significantly impacted the diversity and abundance of the hemp rhizosphere microbiota structure, and it substantially increased the abundance of the phyla Archaea and Rokubacteria. However, the abundances of the phyla Pseudomonadota and Gemmatimonadetes were substantially decreased in treatments with fungicides compared to those without fungicides in the four hemp cultivars. In addition, the diversity and abundance of the rhizosphere microbiota structure were influenced by hemp cultivars. The influence of Cherry Citrus on the diversity and abundance of the hemp rhizosphere microbiota structure was less compared to the other three hemp cultivars (Otto II, BaOx, and Wife). Moreover, fungicide treatment affected enzymatic activities in the hemp rhizosphere. The application of fungicides significantly decreased enzyme abundance in the rhizosphere of all four hemp cultivars. Enzymes such as dehydrogenase, dioxygenase, hydrolase, transferase, oxidase, carboxylase, and peptidase significantly decreased in all the four hemp rhizosphere treated with fungicides compared to those not treated. These enzymes may be involved in the function of metabolizing organic matter and degrading xenobiotics. The ecological significance of these findings lies in the recognition that fungicides impact enzymes, microbiota structure, and the overall ecosystem within the hemp rhizosphere.}, number={11}, journal={INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES}, author={Xu, Junhuan and Knight, Tyson and Boone, Donchel and Saleem, Muhammad and Finley, Sheree J. and Gauthier, Nicole and Ayariga, Joseph A. and Akinrinlola, Rufus and Pulkoski, Melissa and Britt, Kadie and et al.}, year={2024}, month={Jun} }
 @article{grunwald_bock_chang_de souza_del ponte_toit_dorrance_dung_gent_goss_et al._2024, title={Open Access and Reproducibility in Plant Pathology Research: Guidelines and Best Practices}, volume={4}, ISSN={["1943-7684"]}, DOI={10.1094/PHYTO-12-23-0483-IA}, abstractNote={The landscape of scientific publishing is experiencing a transformative shift towards open access (OA), a paradigm that mandates the availability of research outputs such as data, code, materials, and publications. OA provides increased reproducibility and allows for reuse of these resources. This article provides guidance for best publishing practices of scientific research, data, and associated resources, including code, in APS journals. Key areas such as diagnostic assays, experimental design, data sharing, and code deposition are explored in detail. This guidance is in line with those observed by other leading journals. We hope the information assembled in this paper will raise awareness of best practices and enable greater appraisal of the true effects of biological phenomena in plant pathology.}, journal={PHYTOPATHOLOGY}, author={Grunwald, Niklaus J. and Bock, Clive H. and Chang, Jeff H. and De Souza, Alessandra Alves and Del Ponte, Emerson M. and Toit, Lindsey J. and Dorrance, Anne E. and Dung, Jeremiah and Gent, David and Goss, Erica M. and et al.}, year={2024}, month={Apr} }
 @article{sanabria-velazquez_cubilla_flores-giubi_barua_romero-rodriguez_enciso-maldonado_thiessen_shew_2023, title={First Report of Macrophomina euphorbiicola Causing Charcoal Rot of Stevia in Paraguay}, volume={107}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-06-21-1279-PDN}, abstractNote={Stevia (Stevia rebaudiana [Bertoni] Bertoni) is a perennial plant originating in Paraguay. Stevia is primarily cultivated for the production of non-caloric sweeteners. In December 2018, wilted stevia cv. 'PC4' were recovered from two separate fields of 0.3 ha (24.66 S 56.46 W) and 0.5 ha (24.69 S 56.44 W), both with 3 years history of stevia production in San Estanislao County, San Pedro, Paraguay. The wilted plants were randomly distributed in beds covered with plastic mulch and a 30% disease incidence was recorded. Dark brown septate hyphae and microsclerotia were observed on stem bases and black necrotic roots of the wilted plants. Root and crown regions were washed, cut into 0.5 to 1.0 cm pieces, and then surface-disinfested with 0.6% NaOCl before placing them in Petri dishes containing acidified potato-dextrose-agar. Plates were incubated for one week at 25 ± 5°C under fluorescent light with a 12 h photoperiod yielding five isolates SP1PY, SP2PY, SP3PY, SP4PY and SP5PY with gray-black colonies without conidia but showing numerous microsclerotia. Twenty microsclerotia from pure cultures of five isolates were measured, with mean width 38.8 ± 4.7 µm and length 68.8 ± 15.5 µm. Fungal DNA was extracted from mycelia of five isolates for PCR amplification of the internal transcribed spacer (ITS) and translation elongation factor 1-alpha (TEF1-α) using ITS4/ITS5 and EF1-728F/EF-2 primers (Machado et al. 2019). The resultant amplicons were sequenced at Eton Bioscience (Research Triangle Park, NC) and deposited in the NCBI GenBank database (ITS: MT645815, OM956150, OM956151, OM956152, OM956153; and TEF1-α: MT659121, OM959505, OM959506, OM959507, OM959508). Sequences were aligned with several isolates of Macrophomina spp. previously reported (Huda-Shakirah et al. 2019; Machado et al. 2019; Santos et al. 2020; Poudel et al. 2021) using ClustalW. Alignments (ITS and TEF-1α) were concatenated to generate a maximum likelihood tree using MEGA7. The novel isolates grouped into the M. euphorbiicola clade with 95% of bootstrap support. Stevia plants cv. 'Katupyry' were grown in 10 cm-diameter nursery bags containing autoclaved sandy soil and kept under greenhouse conditions (28 ± 5°C; 16 h photoperiod). Fifteen plants per isolate (n=75) were inoculated by adding 20 g of rice infested with M. euphorbiicola to each plant. Infested grains were distributed around the crown of the plant at a depth of 0.5 cm; non-infested rice was added to four control plants. Lower-stem lesions and microsclerotia of M. euphorbiicola developed on all inoculated plants. No lesions or microsclerotia were observed on control plants. The M. euphoribiicola fungus was re-isolated from inoculated stevia plants but not from the non-infested rice treated plants. Koch's postulates were repeated twice with similar results. Previously, M. phaseolina was reported causing charcoal rot on stevia in Egypt (Hilal and Baiuomy 2000), and in North Carolina, USA (Koehler and Shew 2017). However, Paraguayan isolates grouped with isolates of M. euphorbiicola based on the combined sequences of the ITS and TEF-1α regions. Machado et al. (2019) reported M. euphorbiicola causing charcoal rot on castor bean (Ricinus communis) and bellyache bush (Jatropha gossypifolia) in Brazil, which borders northeast Paraguay, a major stevia production area. This pathogen has a significant impact on stevia production during hot, dry weather by reducing the number of harvestable plants and increasing replanting costs in perennial production systems.}, number={1}, journal={PLANT DISEASE}, author={Sanabria-Velazquez, Andres D. D. and Cubilla, Alberto and Flores-Giubi, Maria Eugenia and Barua, Javier E. E. and Romero-Rodriguez, Cristina and Enciso-Maldonado, Guillermo A. A. and Thiessen, LindseyD D. and Shew, H. David}, year={2023}, month={Jan} }
 @article{stephens_gannon_thiessen_cubeta_kerns_2023, title={In Vitro Fungicide Sensitivity and Effect of Organic Matter Concentration on Fungicide Bioavailability in Take-All Root Rot Pathogens Isolated from North Carolina}, volume={24}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-08-22-0072-RS}, abstractNote={ Take-all root rot (TARR) of ultradwarf bermudagrass is caused by Gaeumannomyces graminis (Gg), Gaeumannomyces graminicola (Ggram), Candidacolonium cynodontis (Cc), and Magnaporthiopsis cynodontis (Mc). Multiple pathogens have recently been associated with this disease, and biological parameters such as fungicide sensitivity have not been explored in ultradwarf bermudagrass. Although fungicides are commonly used to mitigate disease development, high organic matter present in the turfgrass system could limit the bioavailability of fungicides. Fungicide bioavailability can be influenced by organic matter concentration, and the physicochemical properties of fungicides could provide insight into their binding affinity. However, the influence of organic matter content on fungicide bioavailability has not been investigated. Therefore, the in vitro sensitivity of Gg, Ggram, Cc, and Mc to 14 different fungicides across three chemical classes was determined. An in vitro bioavailability assay was developed using three fungicides and three organic matter concentrations. Generally, demethylation inhibitor and quinone outside inhibitor fungicides provided the greatest reduction in mycelial growth, whereas succinate dehydrogenase inhibitors did not reduce mycelial growth. These data can serve as a foundation for TARR pathogen sensitivity to inform in vitro fungicide sensitivity studies and field efficacy trials. Pyraclostrobin and propiconazole have a high affinity to bind to organic matter, which was evident as more fungicide was required to inhibit Gg growth as organic matter concentration increased. This was not observed when evaluating azoxystrobin, which has a lower binding affinity. Understanding how TARR pathogens respond to fungicide in vitro and how organic matter concentration affects in vitro sensitivity will improve fungicide selection for management of TARR. }, number={2}, journal={PLANT HEALTH PROGRESS}, author={Stephens, Cameron M. and Gannon, Travis W. and Thiessen, Lindsey D. and Cubeta, Marc A. and Kerns, James P.}, year={2023}, month={Jul}, pages={162–170} }
 @article{sanabria-velazquez_enciso-maldonado_maidana-ojeda_diaz-najera_ayvar-serna_thiessen_shew_2023, title={Integrated Pathogen Management in Stevia Using Anaerobic Soil Disinfestation Combined with Different Fungicide Programs in USA, Mexico, and Paraguay}, volume={13}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy13051358}, abstractNote={Stevia is a semi-perennial crop grown to obtain the diterpene glycosides in its leaves, which are processed to manufacture non-caloric sweeteners. Anaerobic soil disinfestation (ASD) and fungicide application were evaluated for the management of stevia stem rot (SSR) and Septoria leaf spot (SLS) in lab and field experiments. In 2019 and 2021, experiments using carbon sources for ASD were carried out in microplots at NCSU (Clayton, NC, USA). In 2020/21 and 2021/22 seasons, field experiments were conducted at CSAEGRO, Mexico (MX) and CEDIT, Paraguay (PY) using a 2 × 3 factorial design with two ASD treatments and three fungicide treatments. ASD treatments included soil amended with cornmeal (MX) or wheat bran (PY) at a rate of 20.2 Mg ha−1, molasses at 10.1 Mg ha−1, and non-amended controls. Fungicide applications included chemical (azoxystrobin), organic (pyroligneous acid, PA), and a non-treated control. ASD was effective in reducing sclerotia viability of Sclerotium rolfsii in laboratory assays (p < 0.0001) and microplot trials (p < 0.0001) in NC. During field trials, the viability of sclerotia was significantly reduced (p < 0.0001) in soils amended with cornmeal + molasses or wheat bran + molasses as carbon sources for ASD. While there was no significant effectiveness of ASD in reducing SLS in 2020 and 2021 or SSR in MX 2020 field trials (p = 0.83), it did exhibit efficacy on SSR in 2021 (p < 0.001). The application of fungicides was significantly effective in reducing SSR (p = 0.01) and SLS (p = 0.001), with azoxystrobin being the most consistent and PA not being statistically different from the control or azoxystrobin. The effects of ASD on fresh yield were inconsistent, exhibiting significant effects in Mexican fields in 2020 but not in 2021. During Paraguayan field trials, ASD only significantly interacted with fungicide applications in the dry yield in 2022. In the 2020/21 MX and 2020 PY field trials, fungicides were significantly effective in enhancing dry leaf yields, with azoxystrobin showing the highest consistency among treatments and PA variable control. In conclusion, utilizing ASD alongside organic fungicides can be a valuable tool for stevia farmers when the use of chemical fungicides is limited. Further research is required to enhance consistency and reduce the costs associated with these treatments under diverse edaphoclimatic conditions.}, number={5}, journal={AGRONOMY-BASEL}, author={Sanabria-Velazquez, Andres D. and Enciso-Maldonado, Guillermo A. and Maidana-Ojeda, Marco and Diaz-Najera, Jose F. and Ayvar-Serna, Sergio and Thiessen, Lindsey D. and Shew, H. David}, year={2023}, month={May} }
 @article{faske_kandel_allen_grabau_hu_kemerait_lawrence_lawrence_mehl_overstreet_et al._2022, title={Meta-Analysis of the Field Efficacy of Seed- and Soil-Applied Nematicides on Meloidogyne incognita and Rotylenchulus reniformis Across the US Cotton Belt}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-07-21-1529-RE}, abstractNote={ Meta-analysis was used to compare yield protection and nematode suppression provided by two seed-applied and two soil-applied nematicides against Meloidogyne incognita and Rotylenchulus reniformis on cotton across 3 years and several trial locations in the U.S. Cotton Belt. Nematicides consisted of thiodicarb- and fluopyram-treated seed, aldicarb and fluopyram applied in furrow, and combinations of the seed treatments and soil-applied fluopyram. The nematicides had no effect on nematode reproduction or root infection but had a significant impact on seed cotton yield response ([Formula: see text]), with an average increase of 176 and 197 kg/ha relative to the nontreated control in M. incognita and R. reniformis infested fields, respectively. However, because of significant variation in yield protection and nematode suppression by nematicides, five or six moderator variables (cultivar resistance [M. incognita only], nematode infestation level, nematicide treatment, application method, trial location, and growing season) were used depending on nematode species. In M. incognita-infested fields, greater yield protection was observed with nematicides applied in furrow and with seed-applied + in-furrow than with solo seed-applied nematicide applications. Most notable of these in-furrow nematicides were aldicarb and fluopyram (>131 g/ha) with or without a seed-applied nematicide compared with thiodicarb. In R. reniformis-infested fields, moderator variables provided no further explanation of the variation in yield response produced by nematicides. Furthermore, moderator variables provided little explanation of the variation in nematode suppression by nematicides in M. incognita- and R. reniformis-infested fields. The limited explanation by the moderator variables on the field efficacy of nematicides in M. incognita- and R. reniformis-infested fields demonstrates the difficulty of managing these pathogens with nonfumigant nematicides across the U.S. Cotton Belt. }, journal={PLANT DISEASE}, author={Faske, Travis R. and Kandel, Yuba and Allen, Tom W. and Grabau, Zane J. and Hu, Jiahuai and Kemerait, Robert C. and Lawrence, Gary W. and Lawrence, Kathy S. and Mehl, Hillary L. and Overstreet, Charles and et al.}, year={2022}, month={Jul} }
 @article{sanabria-velazquez_enciso-maldonado_maidana-ojeda_diaz-najera_thiessen_shew_2022, title={Validation of Standard Area Diagrams to Estimate the Severity of Septoria Leaf Spot on Stevia in Paraguay, Mexico, and the United States}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-07-22-1609-RE}, abstractNote={ Septoria leaf spot (SLS) affects stevia leaves, reducing their quality. Estimates of SLS severity on different genotypes are made to identify resistance and as a basis to compare management approaches. The use of standard area diagrams (SADs) can improve the accuracy and reliability of severity estimates. In this study, we developed new SADs with six illustrations (0.5, 1, 10, 25, 40, and 75% severity). The SADs were validated by raters with and without experience in estimating SLS. Raters evaluated 40 leaf photos with SLS severities ranging from 0 to 100% without and with the SADs. Agreement (ρc), bias (Cb), precision (r), and intracluster correlation (ρ) coefficients were significantly closer to “true” severity values when the SADs was used by inexperienced (ρc = 0.89; Cb = 0.97; r = 0.90, ρ = 0.81) and experienced (ρc = 0.94; Cb = 0.99; r = 0.95, ρ = 0.91) raters. The SADs were tested under field conditions in Paraguay, Mexico, and the United States, with inexperienced raters assigned to two groups, one SADs trained and the other not trained, that estimated SLS severity three times: first, all raters without SADs and no time limit for the estimates; second, only the SADs-trained group used SADs and no time limit; and third, only the SADs-trained group used SADs, with a time limit of 10 s imposed per specimen assessment. Agreement and reliability of SLS severity estimates significantly improved when raters used the SADs without a time limit. The use of the new SADs improved the accuracy, precision, and reliability of SLS severity estimates, enhancing the uniformity in assessment across different stevia programs. }, journal={PLANT DISEASE}, author={Sanabria-Velazquez, Andres D. and Enciso-Maldonado, Guillermo A. and Maidana-Ojeda, Marco and Diaz-Najera, Jose F. and Thiessen, Lindsey D. and Shew, H. David}, year={2022}, month={Nov} }
 @misc{salcedo_purayannur_standish_miles_thiessen_quesada-ocampo_2021, title={Fantastic Downy Mildew Pathogens and How to Find Them: Advances in Detection and Diagnostics}, volume={10}, ISSN={["2223-7747"]}, url={https://doi.org/10.3390/plants10030435}, DOI={10.3390/plants10030435}, abstractNote={Downy mildews affect important crops and cause severe losses in production worldwide. Accurate identification and monitoring of these plant pathogens, especially at early stages of the disease, is fundamental in achieving effective disease control. The rapid development of molecular methods for diagnosis has provided more specific, fast, reliable, sensitive, and portable alternatives for plant pathogen detection and quantification than traditional approaches. In this review, we provide information on the use of molecular markers, serological techniques, and nucleic acid amplification technologies for downy mildew diagnosis, highlighting the benefits and disadvantages of the technologies and target selection. We emphasize the importance of incorporating information on pathogen variability in virulence and fungicide resistance for disease management and how the development and application of diagnostic assays based on standard and promising technologies, including high-throughput sequencing and genomics, are revolutionizing the development of species-specific assays suitable for in-field diagnosis. Our review provides an overview of molecular detection technologies and a practical guide for selecting the best approaches for diagnosis.}, number={3}, journal={PLANTS-BASEL}, publisher={MDPI AG}, author={Salcedo, Andres F. and Purayannur, Savithri and Standish, Jeffrey R. and Miles, Timothy and Thiessen, Lindsey and Quesada-Ocampo, Lina M.}, year={2021}, month={Mar} }
 @article{beacorn_thiessen_2021, title={First Report of Fusarium lacertarum Causing Fusarium Head Blight on Sorghum in North Carolina}, volume={105}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-05-20-1012-PDN}, abstractNote={In August 2018, sorghum plants (Sorghum bicolor (L.) Moench) from research field plots in Wake County, North Carolina were observed with head blight symptoms including panicles with red lesions, visible mycelium, and necrosis. At the time of collection, all plants in research plots displayed symptoms of Fusarium head blight and panicles averaged 33% area affected by symptoms and signs. From these affected plants, samples (n = 5) were collected for further identification. Symptomatic grains were surface sterilized for one minute in 0.825% sodium hypochlorite solution and rinsed for one minute in sterile, deionized water. After drying on sterile paper towels, grains were plated onto water agar. Resulting fungal hyphal tips were then transferred to antibiotic-amended potato dextrose agar (PDA) and incubated at 25oC. Cultures were incubated for 3 to 5 days. Isolates had abundant white hyphae accompanied with peach-colored pigment production. Macroconidia with 5-6 septations were 23.47 ± 7.74 µm long and 3.47 ± 0.66 µm wide with foot-shaped basal cells, tapering to hooked apical cells. Chlamydospores were present in chains but microconidia were not present. Morphological species recognition (MSR) criteria tentatively identified the isolate as Fusarium lacertarum Subrahm., in the Fusarium incarnatum-equiseti species complex (FIESC) using characteristics described by Leslie and Summerell 2006. Molecular characterization using translation elongation factor 1α (TEF-1 α, primers EF1 and EF2 from O'Donnell et al. 1998), β tubulin (TUB2, primers T1 and T22 from O'Donnell and Cigelnik 1997), and ribosomal protein subunit II (RPB2, primers 5F2 and 11AR from Cerón-Bustamante et al. 2018) was conducted to confirm morphological identification. DNA from the hyphae of pure cultures was extracted using the DNeasy PowerSoil DNA extraction kit according to manufacturer's guidelines. DNA amplification conditions followed the protocols for each primer set (O'Donnell et al. 1998; O'Donnell and Cigelnik 1997; Cerón-Bustamante et al. 2018). BLASTn analysis of TEF-1α (Isolate Accession MT149915, 573bp) alignment had 99.8% identity to F. lacertarum (NCBI accession: JF740828), TUB2 (Isolate Accession MT149914, 1,183bp) alignment had 99.3% identity to F. equiseti (NCBI accession: KJ396338), and RPB2 (Isolate Accession MT184173, 1,538bp) concatenated sequences had 95.3% identity to F. lacertarum (NCBI accession: MH582185). The TUB2 region most closely aligns to F. equiseti, which is likely due to an absence of TUB2 sequences labeled for F. lacertarum in the NCBI database. Pathogenicity was confirmed by spray-inoculating Southern Harvest 80G4 sorghum panicles (n = 9) at anthesis with four ml of conidial suspension (3.3×104 conidia/ml). Control plants (n = 9) were sprayed with sterile water. Plastic bags were placed around panicles for 24 hours to ensure moist conditions during the infection period. Plants were maintained in a greenhouse under a 12-hour light cycle and fertilized bi-weekly with 20-20-20 fertilizer. Symptoms were observed on inoculated panicles after 14 days, and the F. lacertarum isolate was recovered from inoculated plants and confirmed using methods described above. Fusarium spp. were not re-isolated from non-inoculated control plants. Members of FIESC are known to contribute to the Fusarium Head Blight disease complex and may be capable of producing mycotoxins associated with infections (Lincy et al. 2011; Marin et al. 2012; Moretti 2017); however, mycotoxin characterization in F. lacertarum has not been characterized. To our knowledge, this is the first report of F. lacertarum causing disease to sorghum in North Carolina and the United States. Fusarium lacertarum may cause impactful losses to sorghum producers due to direct yield and quality losses by the pathogen as well as the potential for mycotoxins to impact trade.}, number={3}, journal={PLANT DISEASE}, author={Beacorn, J. A. and Thiessen, L. D.}, year={2021}, month={Mar} }
 @misc{garcia-rodriguez_thiessen_2021, title={Plant-Microbiome Interactions for Bacterial Wilt Suppression in Modern Tobacco Production}, volume={22}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-08-20-0069-RV}, abstractNote={ The soil-borne bacterium Ralstonia solanacearum continues to represent a major threat to flue-cured tobacco (Nicotiana tabacum) production in the southeastern United States and other major producing regions throughout the world. Beneficial microorganisms naturally found in the soil represent an alternative solution for R. solanacearum’s suppression that may reduce soil health impacts of current management strategies. Biological controls and microbiota manipulation together represent a unique opportunity to reduce disease caused by R. solanacearum. Current high-throughput DNA sequencing technologies and advances in bioinformatic analyses enable culture-independent approaches to study root-associated microorganisms and their interactions. The structure and dynamics of tobacco root-associated microbiota, as well as functional capacities of certain taxa, may improve how we apply disease management strategies in the field. Through this review we summarize our current understanding on (i) the role of bacterial microbiota on R. solanacearum survival, (ii) the impacts of current management strategies on the soil bacterial communities, (iii) the rhizospheric and core microbiome composition and inheritance, (iv) the manipulation of the microbiota for enhanced disease suppression, and (v) the shortcomings of the application of plant-associated bacteria for disease suppression. }, number={1}, journal={PLANT HEALTH PROGRESS}, author={Garcia-Rodriguez, Raymond O. and Thiessen, Lindsey D.}, year={2021}, pages={2–10} }
 @article{gorny_ye_cude_thiessen_2021, title={Soybean Root-Knot Nematode: A Diagnostic Guide}, volume={22}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-01-21-0005-DG}, abstractNote={Root-knot nematodes (Meloidogyne spp.) are one of the most economically important plant parasites in the world, and significantly impacts soybean production in places where they are endemic. Several species of root-knot nematode are capable of causing significant damages to soybean and have broad host ranges that include common rotational crops and weeds. Symptoms of root-knot nematode infections may be confused with other diseases, nutritional disorders, or common root features associated with legumes. The purpose of this diagnostic guide is to provide information regarding identification, isolation, storage, and other relevant aspects of this pathosystem.}, number={2}, journal={PLANT HEALTH PROGRESS}, author={Gorny, Adrienne M. and Ye, Weimin and Cude, Sam and Thiessen, Lindsey}, year={2021}, pages={164–175} }
 @article{bradley_allen_sisson_bergstrom_bissonnette_bond_byamukama_chilvers_collins_damicone_et al._2021, title={Soybean Yield Loss Estimates Due to Diseases in the United States and Ontario, Canada, from 2015 to 2019}, volume={22}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-01-21-0013-RS}, abstractNote={ Soybean (Glycine max [L.] Merrill) yield losses as a result of plant diseases were estimated by university and government plant pathologists in 29 soybean producing states in the United States and in Ontario, Canada, from 2015 through 2019. In general, the estimated losses that resulted from each of 28 plant diseases or pathogens varied by state or province as well as year. Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) caused more than twice as much loss as any other disease during the survey period. Seedling diseases (caused by various pathogens), Sclerotinia stem rot (white mold) (caused by Sclerotinia sclerotiorum [Lib.] de Bary), and sudden death syndrome (caused by Fusarium virguliforme O’Donnell & T. Aoki) caused the next greatest yield losses, in descending order. Following SCN, the most damaging diseases in the northern United States and Ontario differed from those in the southern United States. The estimated mean economic loss from all soybean diseases, averaged across the United States and Ontario, Canada was US$45 per acre (US$111 per hectare). The outcome from the current survey will provide pertinent information regarding the important soybean diseases and their overall severity in the soybean crop and help guide future research and Extension efforts on managing soybean diseases. }, number={4}, journal={PLANT HEALTH PROGRESS}, author={Bradley, Carl A. and Allen, Tom W. and Sisson, Adam J. and Bergstrom, Gary C. and Bissonnette, Kaitlyn M. and Bond, Jason and Byamukama, Emmanuel and Chilvers, Martin I and Collins, Alyssa A. and Damicone, John P. and et al.}, year={2021}, pages={483–495} }
 @article{ernst_thiessen_2020, title={Cercospora nicotianae Isolates from Flue-Cured Tobacco in North Carolina Found with G143A and F1291 Mutations in Cytochrome b Gene}, volume={21}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-04-20-0029-RS}, abstractNote={ Frogeye leaf spot of tobacco caused by Cercospora nicotianae (Ellis & Everhart) is a widespread disease of cultivated tobacco. Recently, flue-cured tobacco producers in North Carolina reported losses due to frogeye leaf spot disease despite the use of strobilurin fungicides. Isolates (n = 4) were obtained in 2018 from affected tobacco leaves from Cumberland, Lenoir, and Nash counties. In 2019, isolates (n = 28) were collected from a field in Wilson county. After sequencing the cytb region of 32 isolates, 30 contained a single point mutation conferring a G143A or F129L amino acid change that resulted in quinone outside inhibitor (QoI) fungicide resistance. Although these resistance mutations have been found in air-cured tobacco in Kentucky, to the best of our knowledge, the present study is the first to report QoI resistance mutations in C. nicotianae populations in flue-cured tobacco and a first report in North Carolina. }, number={4}, journal={PLANT HEALTH PROGRESS}, author={Ernst, Andrew and Thiessen, Lindsey}, year={2020}, pages={288–290} }
 @article{mueller_wise_sisson_allen_bergstrom_bissonnette_bradley_byamukama_chilvers_collins_et al._2020, title={Corn Yield Loss Estimates Due to Diseases in the United States and Ontario, Canada, from 2016 to 2019}, volume={21}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-05-20-0038-RS}, abstractNote={ Annual reductions in corn (Zea mays L.) yield caused by diseases were estimated by university Extension-affiliated plant pathologists in 26 corn-producing states in the United States and in Ontario, Canada, from 2016 through 2019. Estimated loss from each disease varied greatly by state or province and year. Gray leaf spot (caused by Cercospora zeae-maydis Tehon & E.Y. Daniels) caused the greatest estimated yield loss in parts of the northern United States and Ontario in all years except 2019, and Fusarium stalk rot (caused by Fusarium spp.) also greatly reduced yield. Tar spot (caused by Phyllachora maydis Maubl.), a relatively new disease in the United States, was estimated to cause substantial yield loss in 2018 and 2019 in several northern states. Gray leaf spot and southern rust (caused by Puccinia polysora Underw.) caused the most estimated yield losses in the southern United States. Unfavorable wet and delayed harvest conditions in 2018 resulted in an estimated 2.5 billion bushels (63.5 million metric tons) of grain contaminated with mycotoxins. The estimated mean economic loss due to reduced yield caused by corn diseases in the United States and Ontario from 2016 to 2019 was US$55.90 per acre (US$138.13 per hectare). Results from this survey provide scientists, corn breeders, government agencies, and educators with data to help inform and prioritize research, policy, and educational efforts in corn pathology and disease management. }, number={4}, journal={PLANT HEALTH PROGRESS}, author={Mueller, Daren S. and Wise, Kiersten A. and Sisson, Adam J. and Allen, Tom W. and Bergstrom, Gary C. and Bissonnette, Kaitlyn M. and Bradley, Carl A. and Byamukama, Emmanuel and Chilvers, Martin I and Collins, Alyssa A. and et al.}, year={2020}, pages={238–247} }
 @article{warneke_thiessen_mahaffee_2020, title={Effect of Fungicide Mobility and Application Timing on the Management of Grape Powdery Mildew}, volume={104}, ISBN={1943-7692}, DOI={10.1094/PDIS-06-19-1285-RE}, abstractNote={Grape powdery mildew (GPM) fungicide programs consist of 5 to 15 applications, depending on region or market, in an attempt to achieve the high fruit quality standards demanded by the market. Understanding how fungicides redistribute and targeting redistributing fungicide to critical crop phenological stages could improve fungicide protection of grape clusters. This study evaluated fungicide redistribution in grapevines from major fungicide groups labeled for GPM control. Translaminar and xylem redistribution was examined by placing fungicide-impregnated filter disks on the adaxial or abaxial leaf surface of detached leaves for 10 min and then incubating for 48 h before inoculating the abaxial surface with conidia. Vapor redistribution used Teflon disks sprayed with fungicides and placed on the abaxial leaf surface of detached leaves 48 h before inoculation. Disease development was rated 10 days later. Translaminar movement through calyptra was tested using flowering potted vines. All fungicides tested redistributed through at least one mechanism. Fungicide timing at critical phenological stages (early, mid, and late bloom) was assessed in small plots of cultivar Pinot noir vines. The application of trifloxystrobin, quinoxyfen, or fluopyram at different bloom stages showed that applications initiated at end of bloom resulted in the lowest berry infection probabilities of 0.073, 0.097, and 0.020, respectively. The results of this study suggest that integrating two carefully timed applications of redistributing fungicides initiated at end of bloom into a fungicide program may be an effective strategy for wine grape growers in western Oregon to produce fruit with low GPM infection.}, number={4}, journal={PLANT DISEASE}, author={Warneke, Brent and Thiessen, Lindsey D. and Mahaffee, Walter F.}, year={2020}, month={Apr}, pages={1167–1174} }
 @article{thiessen_schappe_zaccaron_conner_koebernick_jacobson_huseth_2020, title={First Report of Cotton Leafroll Dwarf Virus in Cotton Plants Affected by Cotton Leafroll Dwarf Disease in North Carolina}, volume={104}, ISSN={0191-2917 1943-7692}, url={http://dx.doi.org/10.1094/PDIS-02-20-0335-PDN}, DOI={10.1094/PDIS-02-20-0335-PDN}, abstractNote={HomePlant DiseaseVol. 104, No. 12First Report of Cotton Leafroll Dwarf Virus in Cotton Plants Affected by Cotton Leafroll Dwarf Disease in North Carolina PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Cotton Leafroll Dwarf Virus in Cotton Plants Affected by Cotton Leafroll Dwarf Disease in North CarolinaLindsey D. Thiessen, Tyler Schappe, Marcio Zaccaron, Kassie Conner, Jenny Koebernick, Alana Jacobson, and Anders HusethLindsey D. Thiessen†Corresponding author: L. D Thiessen; E-mail Address: ldthiess@ncsu.eduhttp://orcid.org/0000-0001-5029-0139North Carolina State University, Raleigh, NC 27695Search for more papers by this author, Tyler SchappeNorth Carolina State University, Raleigh, NC 27695Search for more papers by this author, Marcio ZaccaronAuburn University, Auburn, AL 36849Search for more papers by this author, Kassie ConnerAlabama Cooperative Extension System, Auburn University, Auburn, AL 36849Search for more papers by this author, Jenny KoebernickAuburn University, Auburn, AL 36849Search for more papers by this author, Alana JacobsonAuburn University, Auburn, AL 36849Search for more papers by this author, and Anders HusethNorth Carolina State University, Raleigh, NC 27695Search for more papers by this author AffiliationsAuthors and Affiliations Lindsey D. Thiessen1 † Tyler Schappe1 Marcio Zaccaron2 Kassie Conner3 Jenny Koebernick2 Alana Jacobson2 Anders Huseth1 1North Carolina State University, Raleigh, NC 27695 2Auburn University, Auburn, AL 36849 3Alabama Cooperative Extension System, Auburn University, Auburn, AL 36849 Published Online:8 Oct 2020https://doi.org/10.1094/PDIS-02-20-0335-PDNAboutSectionsView articlePDFSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleDuring the 2019 growing season, cotton (Gossypium hirsutum L.) plants in North Carolina were observed to have virus-like symptoms including leaf rugosity, leaf curling, and shortened upper internodes, consistent with cotton leafroll dwarf disease (CLRDD) associated with cotton leafroll dwarf virus (CLRDV, family Luteoviridae, genus Polerovirus) (Avelar et al. 2020). Sentinel plots planted on June 17, 2019, at the Sandhills Research Station in Moore County, NC, exhibited CLRDD symptoms, and disease incidence was estimated at 75% on a 0.1-ha field. Cotton aphids (Aphis gossypii Glover), the reported vector of CLRDV (Heilsnis et al. 2020; McLaughlin et al. 2020; Michelotto and Busoli 2007), were detected on plants throughout the growing season. Samples (n = 24) were collected from sentinel plots on September 20, 2019, to test for CLRDV through reverse transcription PCR. Each sample represented five symptomatic plants collected from a single plot. Total RNA was extracted from the petiole tissue of each sample using a Qiagen RNeasy Plant Mini kit (Qiagen, Germantown, MD), following the manufacturer’s recommendations. The cDNA was synthesized using a SuperScript IV first-strand synthesis system (ThermoFisher Scientific, Waltham, MA) and amplified with CLRDV-specific PCR primers CLRDV3675F/Pol3982R (Sharman et al. 2015) targeting a 310-bp genome segment of ORF3-5. Seven CLRDV-positive samples were further amplified with two additional primer sets specifically designed to detect CLRDV: AL674F/AL1407R (Avelar et al. 2019), targeting a 733-bp portion of the ORF0-ORF1, and CLPOF/CLPOR (Cascardo et al. 2015), amplifying an 880-bp fragment spanning the ORF0. Nucleotide BLAST searches showed that the best matches for all sequences in this study were derived from CLRDV with a range of pairwise identity of 99.2 to 100% for all genome segments. From symptomatic samples (n = 14), the isolated virus was confirmed as CLRDV in several cotton varieties, including Deltapine 1646 B2XF (GenBank accessions MN958131 [ORF3-5], MN958147 [ORF0-ORF1], MN958138 [ORF0], MN958133 [ORF3-5], MN958145 [ORF0-ORF1], and MN958140 [ORF0]), Phytogen 480 W3FE (MN958134 [ORF3-5], MN958144 [ORF0-ORF1], and MN958141 [ORF0]), Stoneville 5471 GLTP (MN958135 [ORF3-5], MN958143 [ORF0-ORF1], and MN958142 [ORF0]), and Nextgen 5711 B3XF (MN958130 [ORF3-5], MN958148 [ORF0-ORF1], MN958137 [ORF0], MN958132 [ORF3-5], MN958146 [ORF0-ORF1], MN958139 [ORF0], and MN958136 [ORF3-5]). CLRDD is a newly named disease of cotton in the United States that was first reported in Alabama (Avelar et al. 2019), Georgia (Tabassum et. al. 2019), Mississippi (Aboughanem-Sabanadzovic et. al. 2019), and Texas (Alabi et al. 2020). Although the virus has been reported with variable impacts, losses can be extensive in some fields that are affected (Avelar et al. 2019). North Carolina produced over one million bales of cotton in 2019, and given reported losses among fields with high disease incidence, CLRDV has the potential to significantly reduce cotton yield and quality for the state if it becomes widespread.The author(s) declare no conflict of interest.References:Aboughanem-Sabanadzovic, N., et al. 2019. Plant Dis. 103:1798. https://doi.org/10.1094/PDIS-01-19-0017-PDN Link, ISI, Google ScholarAlabi, O. J., et al. 2020. Plant Dis. 104:998. https://doi.org/10.1094/PDIS-09-19-2008-PDN Link, ISI, Google ScholarAvelar, S., et al. 2019. Plant Dis. 103:592. https://doi.org/10.1094/PDIS-09-18-1550-PDN Link, ISI, Google ScholarAvelar, S., et al. 2020. Plant Dis. 104:780. https://doi.org/10.1094/PDIS-06-19-1316-RE Link, ISI, Google ScholarCascardo, R. S., et al. 2015. Virol. J. 12:123. https://doi.org/10.1186/s12985-015-0356-7 Crossref, ISI, Google ScholarHeilsnis, B., et al. 2020. Proc. Beltwide Cotton Conf., Austin, TX. Google ScholarMcLaughlin, A. K., et al. 2020. Proc. Beltwide Cotton Conf., Austin, TX. Google ScholarMichelotto, M. D., and Busoli, A. C. 2007. Campinas 66:441. Google ScholarSharman, M., et al. 2015. Australas. Plant Dis. Notes 10:24. https://doi.org/10.1007/s13314-015-0174-1 Crossref, ISI, Google ScholarTabassum, A., et al. 2019. Plant Dis. 103:1803. https://doi.org/10.1094/PDIS-12-18-2197-PDN Link, ISI, Google ScholarThe author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 104, No. 12 December 2020SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionUredinia of Phragmidium violaceum on European blackberry (K. J. Evans et al.). Photo credit: L. Morin. Strawberry fruit rot caused by Sclerotinia sclerotiorum (M. V. Marin and N. A. Peres). Photo credit: M. V. Marin. Metrics Downloaded 897 times Article History Issue Date: 1 Dec 2020Published: 8 Oct 2020First Look: 26 Jun 2020Accepted: 23 Jun 2020 Page: 3275 Information© 2020 The American Phytopathological SocietyKeywordscotton leafroll dwarf viruscottonCLRDVviruses and viroidsThe author(s) declare no conflict of interest.PDF downloadCited ByInvestigating the effects of planting date and Aphis gossypii management on reducing the final incidence of cotton leafroll dwarf virusCrop Protection, Vol. 158Complete Genome Sequence of Cotton Leafroll Dwarf Virus Infecting Cotton in Oklahoma, USAMicrobiology Resource Announcements, Vol. 11, No. 7First Report of Cotton Leafroll Dwarf Virus Infecting Hibiscus syriacus in South KoreaDavaajargal Igori, Ah-Young Shin, Se Eun Kim, Suk-Yoon Kwon, and Jae Sun Moon5 February 2022 | Plant Disease, Vol. 0, No. jaCotton Leafroll Dwarf Virus US Genomes Comprise Divergent Subpopulations and Harbor Extensive Variability5 November 2021 | Viruses, Vol. 13, No. 11Effect of Cotton Leafroll Dwarf Virus on Physiological Processes and Yield of Individual Cotton Plants1 October 2021 | Frontiers in Plant Science, Vol. 12Genome analysis of cotton leafroll dwarf virus reveals variability in the silencing suppressor protein, genotypes and genomic recombinants in the USA7 July 2021 | PLOS ONE, Vol. 16, No. 7Natural host range, incidence on overwintering cotton and diversity of cotton leafroll dwarf virus in Georgia USACrop Protection, Vol. 144}, number={12}, journal={Plant Disease}, publisher={Scientific Societies}, author={Thiessen, Lindsey D. and Schappe, Tyler and Zaccaron, Marcio and Conner, Kassie and Koebernick, Jenny and Jacobson, Alana and Huseth, Anders}, year={2020}, month={Dec}, pages={3275} }
 @article{schappe_ritchie_thiessen_2020, title={First Report of Serratia marcescens Causing a Leaf Spot Disease on Industrial Hemp (Cannabis sativa)}, volume={104}, ISBN={1943-7692}, DOI={10.1094/PDIS-04-19-0782-PDN}, abstractNote={In the 2017 and 2018 growing seasons (between May and October), several cultivars of industrial hemp plants grown for flowers in greenhouse production from four North Carolina counties showed symptoms of an angular leaf spot on leaves, stems, and flower parts. Lesions were initially small, dark brown, 1 to 3 mm in size, and vein-limited. As the disease progressed, lesions coalesced to form larger regions of necrosis that engulfed large portions of leaves, and whole plants were lost to disease. Red bacterial ooze was observed streaming from the plant tissues. Bacterial colonies growing on potato dextrose agar (PDA) were raised and dark-pink colored. The Gram stain indicated gram-negative bacilli. A representative isolate (called strain T2) was used to inoculate Cannabis sativa L. ‘Carmagnola’. Two-week-old seedlings (n = 6) were inoculated with a bacterial suspension (OD₆₀₀ = 0.1, approximately 10⁸ CFU/ml) using a PreVal hand sprayer; additional seedlings (n = 6) were inoculated with sterile water to serve as the negative control. Plants were incubated at 23°C for 21 days in a growth chamber with a 12-h photoperiod. After 8 days, dark brown-black lesions similar to those described above were observed on inoculated leaves. Control plants remained symptomless. The pathogen of interest was the only microorganism reisolated from lesions, and after transferring onto PDA, colonies were identical in morphology to those isolated from the original diseased plants. Molecular identification was conducted by first extracting DNA from the representative isolate T2 using the DNeasy Powersoil kit (Qiagen, Hilden, Germany). The 16S ribosomal RNA region (Klindworth et al. 2013) and the RNA polymerase β-subunit (rpoB) gene (Mollet et al. 1997) were PCR amplified. Amplicons were sequenced at the North Carolina State Genomic Sciences Laboratory, and sequences for each gene from the isolate assessed (T2) were deposited to GenBank (accessions MK598699 and MN400982 for 16S rRNA and rpoB, respectively). NCBI-BLAST searches (Altschul et al. 1997) showed the highest similarity (99.6% identity) with 16S rRNA of Serratia marcescens subsp. sakuensis and 99.6% pairwise identity to rpoB of S. marcescens strain B3R3 (GenBank accession KU894791). Based on pathogenicity, morphology, and molecular identification, the unknown bacterial isolate was identified as S. marcescens. Because industrial hemp is increasingly grown across the United States for cannabidiol production, this disease could pose significant challenges and cause yield reduction in affected plants. Additionally, this pathogen could be of human health concern should it survive hemp processing practices, because there are strains that affect humans.}, number={4}, journal={PLANT DISEASE}, author={Schappe, T. and Ritchie, D. F. and Thiessen, L. D.}, year={2020}, month={Apr}, pages={1248–1249} }
 @article{thiessen_ellington_macialek_johnson_reed_2020, title={Sanitation of Float Trays for the Management of Pythium Species in Tobacco Float Systems}, volume={21}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-07-19-0047-RS}, abstractNote={ Pythium root rot is an economically important disease threatening greenhouse production of tobacco seedlings. Although methyl bromide was historically used for tray sanitation, the phase-out of the fumigant from agricultural use has left few options for growers to produce disease-free transplants. Steam sanitation at 80°C for 30 min has shown control of disease caused by Rhizoctonia solani and has been adopted for use to manage Pythium spp. This study evaluates other steam temperatures and time durations to effectively manage Pythium spp. in float-tray systems. Naturally infested trays steamed at 63, 71, and 77°C for 30 min significantly reduced Pythium spp. from trays compared with TriSan wash and CC-15 dip treatments. Float trays inoculated with Pythium spp. that were steamed at 70 and 80°C for 2 h 30 min, respectively, also significantly reduced Pythium spp. survival. Other fungi, likely saprophytic or beneficial organisms, were not significantly impacted by any steaming treatment. }, number={1}, journal={PLANT HEALTH PROGRESS}, author={Thiessen, Lindsey D. and Ellington, Grant H. and Macialek, Justin A. and Johnson, Chuck S. and Reed, David T.}, year={2020}, pages={21–25} }
 @article{thiessen_schappe_cochran_hicks_post_2020, title={Surveying for Potential Diseases and Abiotic Disorders of Industrial Hemp (Cannabis sativa) Production}, volume={21}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-03-20-0017-RS}, abstractNote={ Industrial hemp (Cannabis sativa L.) has recently been reintroduced as an agricultural commodity in the United States, and, through state-led pilot programs, growers and researchers have been investigating production strategies. Diseases and disorders of industrial hemp in the United States are largely unknowns because record-keeping and taxonomy have improved dramatically in the last several decades. In 2016, North Carolina launched a pilot program to investigate industrial hemp, and diseases and abiotic disorders were surveyed in 2017 and 2018. Producers, consultants, and agricultural extension agents submitted samples to the North Carolina Department of Agriculture and Consumer Services Agronomic Services Division (n = 572) and the North Carolina Plant Disease and Insect Clinic (n = 117). Common field diseases found included Fusarium foliar and flower blights (Fusarium graminearum), Fusarium wilt (Fusarium oxysporum), and Helminthosporium leaf spot (Exserohilum rostratum). Greenhouse diseases were primarily caused by Pythium spp. and Botrytis cinerea. Common environmental disorders were attributed to excessive rainfall flooding roots and poor root development of transplanted clones. }, number={4}, journal={PLANT HEALTH PROGRESS}, author={Thiessen, Lindsey D. and Schappe, Tyler and Cochran, Sarah and Hicks, Kristin and Post, Angela R.}, year={2020}, pages={321–332} }
 @article{thiessen_schappe_2019, title={First Report of Exserohilum rostratum Causing Foliar Blight of Industrial Hemp (Cannabis saliva)}, volume={103}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-08-18-1434-PDN}, abstractNote={HomePlant DiseaseVol. 103, No. 6First Report of Exserohilum rostratum Causing Foliar Blight of Industrial Hemp (Cannabis sativa) PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Exserohilum rostratum Causing Foliar Blight of Industrial Hemp (Cannabis sativa)L. D. Thiessen and T. SchappeL. D. Thiessen†Corresponding author: L. D. Thiessen; E-mail Address: ldthiess@ncsu.eduNorth Carolina State University, Raleigh, NC, 27695Search for more papers by this author and T. SchappeNorth Carolina State University, Raleigh, NC, 27695Search for more papers by this authorAffiliationsAuthors and Affiliations L. D. Thiessen † T. Schappe North Carolina State University, Raleigh, NC, 27695 Published Online:3 Apr 2019https://doi.org/10.1094/PDIS-08-18-1434-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In the 2017 and 2018 growing seasons (between May and October), industrial hemp plants of several cultivars including those grown for fiber, seed, and flower from numerous counties in North Carolina showed foliar, stem, and floral blight symptoms. Plants were collected from samples submitted to the North Carolina State University Plant Disease and Insect Clinic. Lesions on leaves were round, brown to black, with dark margins. Inside of each lesion, abundant conidia were found. Conidia were rostrate, ellipsoidal to narrowly obclavate, straight or slightly curved, olive-brown, with a protuberant, cylindrical hilum at the base. Conidia were 7 to 12 septate and 75.64 ± 8.31 × 15.61 ± 1.41 µm. Conidiophores were cylindrical, olivaceous-brown with swollen conidiogenous cells containing circular conidial scars. Isolates were obtained by transferring single spores to water agar and then transferring to potato dextrose agar (PDA). On PDA, mycelia were initially white, turning dark brown to black after 2 to 3 days. To fulfill Koch’s postulates, a representative isolate of Exserohilum rostratum (syn. Setospaeria rostrata) was used to inoculate Cannabis sativa L. ‘Carmagnola’. Two-week-old seedlings (n = 6) were inoculated with a conidial suspension (106/ml) using a PreVal hand sprayer, and inoculated seedlings were compared with a water control plant. Plants were incubated at 23°C for 21 days in a growth chamber with a 12-h photoperiod. After 8 days, dark brown lesions were found on inoculated leaves. Lesions were small and varied from 5 mm to 1 cm. After 3 weeks, lesions were surface sterilized in 10% bleach solution for 1 min, rinsed with sterile deionized water, and placed onto PDA. The pathogen of interest was the only microorganism reisolated from lesions, and spores were identical in morphology to those originally isolated. Molecular identification was conducted by first extracting DNA from a representative pure culture using the DNeasy Powersoil kit (Qiagen, Hilden, Germany). The ITS1, 5.8S, and ITS2 regions were amplified via polymerase chain reaction using ITS1f (Gardes and Bruns 1993) and ITS4 (White et al. 1990) primers, and the RPB2 gene was amplified using the bRPB2-6F and bRPB2-7R primers (Matheny 2005). Amplicons were purified using AmpureXP magnetic beads and sequenced using Sanger sequencing at the North Carolina State Genomic Sciences Lab. Forward and reverse raw sequences were trimmed, and a consensus sequence was generated and aligned with ITS and RPB2 sequences of 19 representative isolates of all Setosphaeria species (syn. Exserohilum) in GenBank using MUSCLE (Edgar 2004). A maximum likelihood phylogenetic tree was constructed using PhyML 3.2.2 (Guindon et al. 2010) with 500 bootstrap replicates. In addition, NCBI-BLAST searches (Altschul et al. 1997) of the ITS and RPB2 sequences showed the greatest identity with Setosphaeria longirostrata (99.8% pairwise identity, syn. E. rostratum) and S. rostrata (99.5% pairwise identity, syn. E. rostratum), respectively. Sequence data for ITS1 from the isolate assessed was deposited to GenBank (accession MH779469). Based on the morphological (Seifert and Gams 2011) and molecular identification using three barcoding regions, the fungal isolates were identified as E. rostratum (syn. S. rostrata). As industrial hemp acreage increases in the United States, this disease could limit yield and quality of industrial hemp flower production.The author(s) declare no conflict of interest.References:Altschul, S. F., et al. 1997. Nucleic Acids Res. 25:3389. https://doi.org/10.1093/nar/25.17.3389 Crossref, ISI, Google ScholarEdgar, R. C. 2004. Nucleic Acids Res. 32:1792. https://doi.org/10.1093/nar/gkh340 Crossref, ISI, Google ScholarGardes, M., and Bruns, T. D. 1993. Mol. Ecol. 2:113. https://doi.org/10.1111/j.1365-294X.1993.tb00005.x Crossref, ISI, Google ScholarGuindon, S., et al. 2010. Syst. Biol. 59:307. https://doi.org/10.1093/sysbio/syq010 Crossref, ISI, Google ScholarMatheny, P. B. 2005. Mol. Phylogenet. Evol. 35:1. https://doi.org/10.1016/j.ympev.2004.11.014 Crossref, ISI, Google ScholarSeifert, K. A., and Gams, W. 2011. Persoonia Mol. Phylogeny Evol. Fungi. 27:119. https://doi.org/10.3767/003158511X617435 Crossref, 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. 6 June 2019SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionGreen mottle mosaic and leaf deformation symptoms on watermelon (Sui, Li, Shamimuzzaman, Wu, and Ling). Photo credit: K.-S. Ling. Postharvest rot on cucumber caused by Ceratocystis fimbriata (Li, Xu, Zhang, Song, Xie, Sun, and Huang). Photo credit: H. Song. Metrics Article History Issue Date: 6 Jun 2019Published: 3 Apr 2019First Look: 9 Jan 2019Accepted: 7 Jan 2019 Pages: 1414-1414 Information© 2019 The American Phytopathological SocietyThe author(s) declare no conflict of interest.Cited bySetosphaeria rostrata (leaf spot of grasses)CABI Compendium, Vol. CABI CompendiumDieback and Leaf Spot in Box Elder (Acer negundo) Caused by Exserohilum rostratumCheng-long Liu, Xiang-rong Zheng, and Feng-mao Chen9 November 2021 | Plant Disease, Vol. 105, No. 10Molecular Diagnostics and Pathogenesis of Fungal Pathogens on Bast Fiber Crops18 March 2020 | Pathogens, Vol. 9, No. 3Surveying for Potential Diseases and Abiotic Disorders of Industrial Hemp (Cannabis sativa) ProductionLindsey D. Thiessen, Tyler Schappe, Sarah Cochran, Kristin Hicks, and Angela R. Post14 October 2020 | Plant Health Progress, Vol. 21, No. 4Full Issue PDF25 January 2022 | Plant Health Progress, Vol. 21, No. 4}, number={6}, journal={PLANT DISEASE}, author={Thiessen, L. D. and Schappe, T.}, year={2019}, month={Jun}, pages={1414–1414} }
 @article{garcia_kerns_thiessen_2019, title={Ralstonia solanacearum Species Complex: A Quick Diagnostic Guide}, volume={20}, ISSN={["1535-1025"]}, DOI={10.1094/PHP-04-18-0015-DG}, abstractNote={ Ralstonia solanacearum (Smith 1896) Yabuuchi et al. 1996 is ranked second among the top 10 most economically important plant pathogenic bacteria. The soil-borne bacterium affects over 200 plant species worldwide, including economically and nutritionally important crops, such as potato (Solanum tuberosum), tomato (Solanum lycopersicum), and bananas (Musa spp.). R. solanacearum is a species complex, meaning that the species is composed of strains with differential characteristics, including different metabolic requirements, centers of origin, host range, and ideal environmental conditions for infection. Its nature and the fact that it is a species complex can make R. solanacearum a difficult bacterium to work with, especially when lacking experience. Inappropriate isolation or storage of the pathogen can lead to inaccurate diagnostics or misleading conclusions. Thus, the objectives of this diagnostic guide are to provide adequate methods for isolation, storage, and identification and to discuss other relevant aspects related to this important plant pathogenic bacterium. }, number={1}, journal={PLANT HEALTH PROGRESS}, author={Garcia, Raymond O. and Kerns, Jim P. and Thiessen, Lindsey}, year={2019}, pages={7–13} }