@article{parada-rojas_pecota_almeyda_yencho_quesada-ocampo_2021, title={Sweetpotato Root Development Influences Susceptibility to Black Rot Caused by the Fungal Pathogen <i>Ceratocystis fimbriata}, volume={111}, ISSN={0031-949X 1943-7684}, url={http://dx.doi.org/10.1094/PHYTO-12-20-0541-R}, DOI={10.1094/PHYTO-12-20-0541-R}, abstractNote={ Black rot of sweetpotato, caused by Ceratocystis fimbriata, is an important reemerging disease threatening sweetpotato production in the United States. This study assessed disease susceptibility of the storage root surface, storage root cambium, and slips (vine cuttings) of 48 sweetpotato cultivars, advanced breeding lines, and wild relative accessions. We also characterized the effect of storage root development on susceptibility to C. fimbriata. None of the cultivars examined at the storage root level were resistant, with most cultivars exhibiting similar levels of susceptibility. In storage roots, Jewel and Covington were the least susceptible and significantly different from White Bonita, the most susceptible cultivar. In the slip, significant differences in disease incidence were observed for above- and below-ground plant structures among cultivars, advanced breeding lines, and wild relative accessions. Burgundy and Ipomoea littoralis displayed less below-ground disease incidence compared with NASPOT 8, Sunnyside, and LSU-417, the most susceptible cultivars. Correlation of black rot susceptibility between storage roots and slips was not significant, suggesting that slip assays are not useful to predict resistance in storage roots. Immature, early-developing storage roots were comparatively more susceptible than older, fully developed storage roots. The high significant correlation between the storage root cross-section area and the cross-sectional lesion ratio suggests the presence of an unfavorable environment for C. fimbriata as the storage root develops. Incorporating applications of effective fungicides at transplanting and during early-storage root development when sweetpotato tissues are most susceptible to black rot infection may improve disease management efforts. }, number={9}, journal={Phytopathology®}, publisher={Scientific Societies}, author={Parada-Rojas, C. H. and Pecota, Kenneth and Almeyda, C. and Yencho, G. Craig and Quesada-Ocampo, L. M.}, year={2021}, month={Sep}, pages={1660–1669} }
 @article{fuchs_almeyda_al rwahnih_atallah_cieniewicz_farrar_foote_golino_gomez_harper_et al._2021, title={Economic Studies Reinforce Efforts to Safeguard Specialty Crops in the United States}, volume={105}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-05-20-1061-FE}, abstractNote={ Pathogen-tested foundation plant stocks are the cornerstone of sustainable specialty crop production. They provide the propagative units that are used to produce clean planting materials, which are essential as the first-line management option of diseases caused by graft-transmissible pathogens such as viruses, viroids, bacteria, and phytoplasmas. In the United States, efforts to produce, maintain, and distribute pathogen-tested propagative material of specialty crops are spearheaded by centers of the National Clean Plant Network (NCPN). Agricultural economists collaborated with plant pathologists, extension educators, specialty crop growers, and regulators to investigate the impacts of select diseases caused by graft-transmissible pathogens and to estimate the return on investments in NCPN centers. Economic studies have proven valuable to the NCPN in (i) incentivizing the use of clean planting material derived from pathogen-tested foundation plant stocks; (ii) documenting benefits of clean plant centers, which can outweigh operating costs by 10:1 to 150:1; (iii) aiding the development of disease management solutions that are not only ecologically driven but also profit maximizing; and (iv) disseminating integrated disease management recommendations that resonate with growers. Together, economic studies have reinforced efforts to safeguard specialty crops in the United States through the production and use of clean planting material. }, number={1}, journal={PLANT DISEASE}, author={Fuchs, M. and Almeyda, C. and Al Rwahnih, M. and Atallah, S. S. and Cieniewicz, E. J. and Farrar, K. and Foote, W. R. and Golino, D. A. and Gomez, M. and Harper, S. J. and et al.}, year={2021}, month={Jan}, pages={14–26} }
 @article{hoffmann_talton_nita_jones_al rwahnih_sudarshana_almeyda_2020, title={First Report of Grapevine red blotch virus, the Causal Agent of Grapevine Red Blotch Disease, in Vitis vinifera in North Carolina}, volume={104}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-07-19-1539-PDN}, abstractNote={Grapevine red blotch virus (GRBV), genus Grablovirus, family Geminiviridae, is the causal agent for grapevine red blotch disease (GRBD) (Al Rwahnih et al. 2013; Yepes et al. 2018). GRBV has been found in several wine-grape growing regions in the United States (Krenz et al. 2014), as well as in germplasm repositories (Al Rwahnih et al. 2015). However, the incidence of GRBV in parts of the southeastern United States is unknown. Initial observations between August and October of 2017 in North Carolina (NC) vineyards revealed that the commonly grown red cultivars Vitis vinifera ‘Merlot’, ‘Malbec’, and ‘Cabernet franc’ frequently exhibited leaf symptoms similar to those associated with GRBD. The symptoms were seemingly unrelated to location, management, or age of the plants. A total of 80 grapevine samples were collected from eight blocks in six vineyards (10 vines per block) in three different wine-grape growing regions in NC (Upper Hiwassee Highlands American Viticultural Area [AVA], Crest of the Blue Ridge Henderson County AVA, and Yadkin Valley AVA), following the recommended sampling strategy from Foundation Plant Services (FPS, University of California–Davis) (http://fps.ucdavis.edu/samplecollection.cfm). All samples were collected in October 2018. Blocks were selected based on the cultivar and the visibility of symptomatic leaves. Ten vines with leaf symptoms were selected randomly within each block. Three samples per grapevine were collected, sampling both cordons. Samples were directly stored at 4°C and shipped overnight to the NC State University Micropropagation and Repository Unit for further processing. Following FPS protocols, total nucleic acid (TNA) was extracted from leaf petiole tissue using the RNeasy Mini Kit (Qiagen), and samples were analyzed by quantitative reverse transcription PCR (RT-qPCR) for a panel of viruses known to infect grapevine, including GRBV. GRBV was identified in 21 samples of cultivars Merlot and Malbec in Yadkin and Surry Counties, NC (both Yadkin Valley AVA). All positive vines showed GRBD symptoms. To confirm the RT-qPCR results, aliquots of TNA from GRBV-positive samples were run by end-point PCR for further sequencing. GRBV-specific primers as described by Al Rwahnih et al. (2013) were used. RT-PCR yielded products of the expected size (557 bp) for all positive samples, and they were directly sequenced. All the positive samples shared 100% identity with 22 GRBV GenBank accessions, with the top hit being an isolate from Washington state (MF795177), based on BLASTN analysis. Complete genomes of three representative GRBV samples, one from each positive vineyard, were amplified using Phusion Hot Start Flex 2× Master Mix (NEB) and overlapping primers, GRBV-OL-F (5′-ATTCCTGCAGTTCTAGTGAAAG-3′) and GRBV-OL-R (5′-TAGAACTGCAGGAATCGC-3′). Sequencing of the 3.2-kb amplicons was done and the sequences deposited in GenBank (accession nos. MN186403 to MN186405). The GRBV sequences from NC shared 97 to 99% complete genome identities with isolates from Washington State (MF795161 and MF795177). Phylogenetic analysis revealed the clustering of the three NC isolates into GRBV clade 2 (Krenz et al. 2014). This report is part of a comprehensive survey of NC vineyards to study grapevine virus incidence in the state. The source of the virus is unclear; however, studies are underway to determine source and potential vector capacity in NC. To our understanding, this is the first time GRBV is being reported in NC.}, number={4}, journal={PLANT DISEASE}, author={Hoffmann, M. and Talton, W. and Nita, M. and Jones, T. and Al Rwahnih, M. and Sudarshana, M. R. and Almeyda, C.}, year={2020}, month={Apr}, pages={1266–1266} }
 @article{almeyda_abad_pesic-vanesbroeck_2013, title={First Report of Sweet potato virus G and Sweet potato virus 2 Infecting Sweetpotato in North Carolina.}, volume={97}, ISSN={["1943-7692"]}, DOI={10.1094/pdis-04-13-0359-pdn}, abstractNote={ Sweet potato virus G (SPVG) and Sweet potato virus 2 (SPV2) are two members of the genus Potyvirus, distinct from Sweet potato feathery mottle virus (SPFMV) (1,2,4). The significance of SPVG and SPV2 to sweetpotato (Ipomoea batatas Lam.) is that each virus can synergistically interact with Sweet potato chlorotic stunt virus (SPCSV) inducing sweet potato virus disease (SPVD) (1,2,4). During the summer of 2012, susceptible indicator plants (I. setosa) were evenly distributed in sweetpotato experimental plots at two research stations (Clinton and Kinston) in North Carolina (NC). Naturally infected indicator plants (n = 129) showing virus-like symptoms including vein clearing, chlorotic mosaic, and chlorotic spots were collected and tested for the presence of viruses. Sap extract from plants tested positive for SPVG and SPV2 by nitrocellulose immune-dot blot, using SPVG antiserum obtained from the International Potato Center (Lima, Peru) and SPV2 antiserum kindly provided by C. A. Clark, Louisiana State University. Total RNA was extracted from 200 mg of symptomatic leaf tissue by using the QIAGEN RNeasy Plant Mini Kit (Hilden, Germany) adding 2% PVP-40 and 1% 2-mercaptoethanol to the extraction buffer. Multiplex RT-PCR was carried out using the SuperScript III One-Step RT-PCR System (Invitrogen, Carlsbad, CA) with specific primers designed for simultaneous detection and differentiation of four closely related sweetpotato potyviruses (3). Amplicons were cloned using the pGEM-T Easy cloning kit (Promega, Madison, WI) and sequenced. Quantitative RT-PCR was used for SPCSV detection. Results confirmed the presence of SPVG and SPV2 in single infections on 7% and 0.8% of samples, respectively; and in mixed infections on 54% and 3% of samples, respectively. SPVG was found as the most prevalent in all viral combinations where 14% of samples were infected with SPVG and SPFMV; and 15% of samples were infected with SPVG, SPFMV, and Sweet potato virus C (SPVC). SPV2 was detected in less common combinations (0.8%) associated with SPVG and SPFMV. The mixed infection SPVG and SPCSV as well as the combination SPV2 and SPCSV was detected in 0.8% of samples. Sequence analyses of the samples at nucleotide level (GenBank Accession Nos. KC962218 and KC962219, respectively) showed 99% similarity to SPVG isolates from Louisiana (4) and SPV2 isolates from South Africa (1). Scions from infected indicator plants were wedge grafted onto healthy sweetpotatoes (cvs. Beauregard and Covington). Eight weeks after grafting, chlorotic mosaic was observed on plants with mixed potyvirus infections whereas plants with single potyvirus infection showed no obvious symptoms. RT-PCR testing and sequencing of amplicons corroborate the presence of both viruses initially detected in indicator plants. Additionally, naturally infected sweetpotato samples (n = 102) were collected in the same experimental plots. SPVG and SPV2 were detected and identified following the described methodology. In the United States, SPVG has been shown to be prevalent in Louisiana (4) and the results presented here indicate that SPVG is spreading in NC. Our results confirm the presence of SPVG and SPV2 in NC. To our knowledge, this is the first report of SPVG and SPV2 in sweetpotato fields in NC.  References: (1) E. M. Ateka et al. Arch Virol 152:479, 2007. (2) F. Li et al. Virus Genes 45:118, 2012. (3) F. Li et al. J. Virol. Methods 186:161, 2012. (4) E. R. Souto et al. Plant Dis 87:1226, 2003. }, number={11}, journal={PLANT DISEASE}, author={Almeyda, C. V. and Abad, J. A. and Pesic-VanEsbroeck, Z.}, year={2013}, month={Nov}, pages={1516–1516} }