Patrick Wechter

Director / Research Leader
Research Leader
Plant and Environmental Sciences Department, Coastal Research and Education Center

Office: Coastal Research and Education Center
Phone: 843-402-5398


 Educational Background

Ph.D Plant Pathology
Clemson University 2000

M.S. Plant Pathology
Clemson University 1994

B.S. Biology
Winthrop University 1983


Dr. Wechter was with the USDA, ARS as a Research Plant Pathologist for 18 years. He has also served in different capacities in the American Society of Microbiology, the American Society of Horticultural Science, and the American Phytopathological Society, including service as Senior Editor for Bacteriology for the journal Plant Disease. He is the recipient of the prestigious T. W. Edminster Research Associate Award by USDA (2014) and has over 70 peer-reviewed publications.
Over his career, Dr. Wechter has worked with a variety of pathogens and vegetable crops and has developed important cultivars with significant impact on the vegetable industry. He developed the mustard green cultivar ‘Carolina Broadleaf’, the only commercially available brassica leafy green with resistance to Bacterial Leaf Blight, an important disease in the southern US. He also developed, in collaboration with Clemson Scientists, the watermelon grafting rootstock ‘Carolina Strongback’, which has high levels of tolerance to Fusarium wilt and resistance to root knot nematode. Carolina Strongback has been licensed to Syngenta Seed and has been made available in many countries around the world.

 Research Interests

Bacterial and fungal plant pathogens, molecular genetics of plant resistance, development of molecular markers for marker assisted breeding and resistant germplasm development. Main research thrust is vegetable crops, especially cucurbits, brassica leafy greens and peppers.


Kousik, C. S., Levi, A., Ling, K. S., and Wechter, W. P. Potential sources of resistance to cucurbit powdery mildew (Podosphaera xanthii) in US Plant Introductions (PI) of Lagenaria siceraria (bottle gourd). HortScience 43:1349-1364. 2008.

Harrison, H. F., Mitchell, T. R., Peterson, J. K., Wechter, W. P., and Majetich, G. R. Caffeoylquinic acids in storage roots of sixteen sweetpotato genotypes. Journal of American Society of Horticulture 133:492-500. 2008.

Wechter, W. P., Keinath, A. P., Smith, J. P., and Farnham, M. W. First report of severe outbreaks of bacterial leaf spot of leafy Brassica greens caused by Xanthomonas campestris pv. campestris in South Carolina. Plant Disease 92:1134.2008

Levi, A., Wechter, W. P., and Davis, A. R. EST-PCR markers representing watermelon fruit genes are polymorphic among watermelon heirloom cultivars sharing a narrow genetic base. Plant Genetic Resources 7:16-32. 2008.

Kousik, C. S., Levi, A., Ling, K. S., and Wechter, W. P. Potential sources of resistance to cucurbit powdery mildew (Podosphaera xanthii) in US Plant Introductions (PI) of Lagenaria siceraria (bottle gourd). HortScience 43:1359-1364. 2008.

Wechter, W. P., Levi, A., Harris, K. R., Davis, A.R., Fei, Z., Katzir, N., Giovannoni, J.J., Salman-Minkov, A., Hernandez, A., Thimmapuram, J., Tadmor, Y., Portnoy, V., and Trebitsh, T. Gene expression in developing watermelon fruit. BMC Genomics 9:275-282. 2008.

Harris, K. R., Wechter, W. P., and Levi, A. Isolation, sequence analysis, and linkage mapping of nucleotide binding site-leucine-rich repeat disease resistance gene analogs in watermelon. J. Amer. Soc. Hort. Sci. 134:649-657. 2009.

Ha, Y., Fressehaie, A., Ling, K.-S., Wechter, W. P., Keinath, A. K., and Walcott, R. R. Simultaneous Detection of Acidovorax avenae subsp. citrulli and Didymella bryoniae in cucurbit seedlots using magnetic capture hybridization and real-time polymerase chain reaction. Phytopathology 99:666-678. 2009.

Harris, K. R., Ling, K-S., Wechter, W. P., and Levi, A. Identification and utility of markers linked to the zucchini yellow mosaic virus resistance gene in watermelon. J. Amer. Soc. Hort. Sci. 134:1-6. 2009.

Levi, A., Wechter, W. P., Harris, K.R., Davis, A. R., and Fei, Z. High-frequency oligonucleotides in watermelon expressed sequence tag-unigenes are useful in producing polymorphic polymerase chain reaction markers among watermelon genotypes. J. Amer. Soc. Hort. Sci. 135:369-378. 2010.

Wechter, W. P., Keinath, A. P., Farnham, M. W., and Smith, J. P. First report of bacterial blight on broccoli and cabbage caused by Pseudomonas syringae pv. alisalensis in South Carolina. Plant Disease 94:132. 2010.

Levi, A., Harris, K. R., Wechter, W. P., Kousik, C. S., and Thies, J. A. DNA markers and pollen morphology reveal that Praecitrullus fistulosus is more closely related to Benincasa hispida than to Citrullus spp. Genet. Resour. Crop Evol. 57:1191-1205. 2010.

Ling, K.-S., Wechter, W. P., Somai, B. M., Walcott, R. R., and Keinath, A. P. An improved real-time PCR system for broad-spectrum detection of Didymella bryoniae, the causal agent of gummy stem blight of cucurbits. Seed Sci. & Technol. 38:692-703. 2010.

Wechter, W. P., Levi, A., Ling, K.-S., Kousik, C., and Block, C. C. Identification of resistance to Acidovorax avenae subsp. citrulli among melon (Cucumis spp.) Plant Introductions. HortScience 46:207-212. 2011.

Levi, A., Wechter, W. P., Massey, L. Carter, L. and Hopkins, D. Genetic linkage map of Citrullus lanatus var. citroides chromosomal segments introgressed into the watermelon cultivar Crimson Sweet (Citrullus lanatus var. lanatus) genome. Amer. J. Plant Sci. 2:93-110. 2011.

Ling, K.-S., Wechter, W. P., Walcott, R. R., and Keinath, A. P. Development of a real-time assay for squash mosaic virus useful for broad spectrum detection of various serotypes and its incorporation into a multiplex seed health assay. J. Phytopath. 159:649-656. 2011.

Wechter, W. P., Kousik, C. S., McMillan, M. L., and Levi, A. Identification of resistance to Fusarium oxysporum f. sp. niveum race 2 in Citrullus lanatus var. citroides plant introductions. HortScience. 47:334-338. 2012.

Yakabe, L. E., MacCree, M. M., Sudarshana, P., McClean, A. E., Parker, S. R., Wechter, W. P., Presting, G., and Kluepfel, D. A. Novel primers for detection of genetically diverse virulent Agrobacterium tumefaciens bv1 strains. J. Gen. Plant Pathol. J.of Gen.Plant Pathol. DOI: 10.1007/s10327-012-0364-z. 2012.

Harrison, H. F., Wechter, W. P., and Kousik, C. S. Inhibition of bacterial, fungal, and plant growth by testa extracts of Citrullus genotypes. HortScience 47:448-451. 2012

Schofield, D. A., Bull, C. T., Wechter, W. P., Westwater, C., and Molineux, I. J. Development of an engineered ‘bioluminescent’ reporter phage for the detection of bacterial blight of crucifers. App. Environ. Microbio. 78:3592-3598. 2012.

Nyczepir, A. P., Kluepfel, D. A., Waldrop, V., and Wechter, W. P. Soil solarization and biological control for managing Mesocriconema xenoplax and Short Life in a newly established peach orchard. Plant Dis. 96:1309-1314. 2012.

Li, R., Shan, G., Hernandez, A. G., Wechter, W. P., Fei, Z., abd Ling, K. S. Deep sequencing of small RNAs in tomato for virus and viroid identification and strain differentiation. PLos One. 7(5):e37127. 2012.

Loper, J. E., Hassan, K. A., Mavrodi, D., Davis, E. W., Lim, C. K., Shaffer, B. T., Elbourne, L. D. H., Stockwell, V. O., Hartney, S. L., Breakwell, K., Henkels, M. D., Tetu, S. G., Rangel, L. I., Kidarsa, T. A., Wilson, N. L., Van Mortel, J., Song, C., Blumhagen, R., Radune, D., Hostetler, J. B., Brinkac, L. M., Durkin, A. S., Kluepfel, D. A., Wechter, W. P., Anderson, A. J., Kin, Y. C., Pierson III, L. S., Pierson, E. A., Lindow, S. E., Raaijmakers, J. M., Weller, D. M., Thomashow, L. S., Allen, A. E., and Paulsen, I. I. Comparative genomics of plant-associated Pseudomonas spp.: Insights into diversity and inheritance of traits involved in multitrophic interactions. PLoS Genetics. 8(7):e1002784. 2012.

Wechter, W. P., Keinath, A. P., McMillan, M. L., Smith, P., and Farnham, M. W. Expression of bacterial blight resistance in Brassica leafy greens under field conditions and inheritance of resistance in a Brassica juncea source. Plant Disease. 97:131-137. 2012.

Schofield, D, Bull, C. T., Wechter, W. P., Westwater, C., Molineux, I.R., and Rubio-Salazar, I. “Light-tagged” bacteriophage as a diagnostic tool for the detection of phytopathogens. Bioengineered. 4:1-5. 2012.

Kousik, C., Ikerd, J. L., Wechter, W. P., Harrison, H. F., and Levi, A. Resistance to Phytophthora fruit rot of watermelon caused by Phytophthora capsici in U.S. Plant Introdutions (PI). HortScience. 47:1682-1689. 2012.

Sarris, P. F., Trantas, E. A., Baltras, D. A., Bull, C. T., Wechter, W. P., Yan, S., Jones, C. D., Dangl, J. L., Panopoulos, N. J., Vinatzer, B. A., and Goumas, D. E. Comparative genomics of multiple strains of Pseudomonas cannabina pv alisalensis, a potential model pathogen of both monocots and dicats. PloS One. 8:1-16. 2013.

Levi, A., Thies, J. A., Wechter, W. P., Farnham, M. W., Weng, Y., and Hassell, R. USVL-360, a novel watermelon tetraploid germplasm line. HortScience. 49:354-357. 2013.

Daley, S., Wechter, W. P., and Hassell, R. Improvement of grafted watermelon transplant survival as a result of size and starch increases over time caused by rootstock fatty alcohol treatment Part II. HortTechnology. 24:350-354. 2014.

Wechter, W. P., Keinath, A. P., Smith, J. P., Farnham, M. W., Bull, C. T., and Schofield, D. A. First report of bacterial leaf blight on mustard greens (Brassica juncea) caused by Pseudomonas cannabina pv alisalensis in Mississippi. Plant Disease. 98:1151. 2014.

Lambel, S., Lanini, B., Vivoda, E., Fauve, J., Wechter, W. P., Harris-Shultz, K., Massey, L. M., and Levi, A. A major QTL associated with Fusarium oxysporum race 1 resistance identified in genetic populations derived from closely related watermelon lines using selective genotyping and genotyping-by-sequencing for SNP discovery. Theoretical and Applied Genetics. 127:2105-2115. 2014.

Wechter, W. P., Katawczik, M. L., Farnham, M. W., and Levi, A. Watermelon germplasm lines USVL246-FR2 and USVL252-FR2 tolerant to Fusarium oxysporum f. sp. niveum race 2. HortScience. 51:1065-1067. 2016.

Wechter, W. P., Katawczik, M. L., Keinath, A. P., Smith, J. P., and Farnham, M. W. ‘Carolina Broadleaf’ mustard green (Brassica juncea L.) resistant to the bacterial leaf blight pathogen Pseudomonas cannabina pv alisalensis. HortScience. 51:1062-1064. 2016.

Keinath, A. P., Wechter, W. P., and Farnham, M. W. Suppression of bacterial blight on mustard greens with host plant resistance and Acibenzolar-S-Methyl. Plant Disease. 100:1921-1926. 2016.

Nimmakayala, P., Tomasson, Y., Abburi, V. K., Saminathan, T., Rodriggues, A. G., Vajja, V. G., Salazar, G., Girish, P., Levi, A., Wechter, W. P., McCreight, J. D., Korol, A., Ronin, Y., Garcia-Mas, J., and Reddy, U. Genome-wide differentiation of various nelon botanical groups for use in genome-wide association study for fruit firmness and construction of a high-resolution genetic map. Frontiers in Plant Science. DOI:10.3389/fpls.2016.01437. 2016.

Daley, J., Branham, S., Levi, A., Hassell, R., and Wechter, W. P. Mapping resistance to Alternaria cucumerina in Cucumis melo. Phytopathology. DOI:10.1094/PHYTO-06-16-0246-R. 2017.

Branham, S., Levi, A., Farnham, M. W., and Wechter, W. P. A GBS-SNP-based linkage map and quantitative trait loci (QTL) associated with resistance to Fusarium oxysporum f. sp. niveum race 2 identified in Citrullus lanatus var. citroides. Theoretical and Applied Genetics. DOI: 10.1007/s00122-16-2813-0. 2017.

Levi, A., Simmons, A. M., Massey, L. M., Coffey, J., Wechter, W. P., Jarret, R. L., Tadmor, Y., Nimmakayala, P., and Reddy, U. Genetic relationships in the desert watermelon Citrullus colocynthis and its genetic relations with other Citrullus taxa as viewed using high frequency oligonucleotide–targeting active gene (HFO–TAG) markers. J. Soc. Hort. Sci. 142:47-57. 2017.

Branham, S., Vexler, L., Meir, A., Tzuri, G., Frieman, Z., Levi, A., Wechter, W.P., Tadmor, Y., Gur, A. 2017. Genetic mapping of a major co-dominant QTL associated with B-carotene accumulation in watermelon. Molecular Breeding. 37:146.

Branham, S.E., Farnham, M.W., Robinson, S.M., and Wechter, W.P. 2018. Identification of resistance to bacterial leaf blight in the USDA collard collection. HortScience 53:838-841.

Branham, S.E., Levi, A., Katawczik, M.M., Fei, Z., and Wechter, W.P. 2018. Construction of a genome-anchored, high-density genetic map for melon (Cucumis melo L.) and identification of Fusarium oxysporum f. sp. melonis race 1 resistance QTL. Theoretical and Applied Genetics: 10.1007/s00122-017-3039-5

Smith, C.L., Freeman, J.H., Kokalis-Burelle, N., and Wechter, W.P. 2019. Screening cucurbit rootstocks for resistance to Meloidogyne spp. and Rotylenchulus reniformis. HoprtScience 54:125-128.

Potnis, N., Branham, S.E., Jones, J.B., and Wechter, W.P. 2019. Genome-wide association study of resistance to Xanthomonas gardneri in USDA Pepper (Capsicum) collection. Phytopathology DOI: 10.1094/PHYTO-06-18-0211-R

Branham, S.E., Levi, A., Katawczik, M.L., and Wechter, W.P. 2019. QTL mapping of resistance to bacterial fruit blotch in Citrullus amarus. Theoretical and Applied Genetics 132:1463-1471.

Branham, S.E., Wechter, W.P., Lambel, S., Massey, L.M., Ma, M., Fauve, J., Farnham,M.W., and Levi, A. 2019. QTL-seq and marker development for resistance to Fusarium oxysporum f. sp. niveum rave 1 in cultivated watermelon. Molecular Breeding 38:139-147.

Zheng, Y., Wu, S., Bai, Y., Sun, H., Jiao, C, Wechter, W, et al., 2019. Cucurbit Genomics Database (CuGenDB): a central portal for comparative and functional genomics of cucurbit crops. Nucleic Acids Research 47:1128-1136.

Branham, S.E., Levi, A., Katawczik, M.L., and Wechter, W.P. 2019. QTL mapping of resistance to bacterial fruit blotch in Citrullus amarus. Theoretical and Applied Genetics 132:1463-1471.

Keinath, A.P., Wechter, W.P., Rutter, W.B., Agudelo, P.A. 2019. Cucurbit rootstocks resistant to Fusarium oxysporum f.sp. niveum remain resistant when co-infected by Meloidogyne incognita in the field. Plant Disease. 103(6):1383-1390.

Wu, S., Wang, X., Reddy, U., Sun, H., Bao, K., Patel, T., Oritz, C., Abburi, L., Nimmakayala, P., Branham, S., Wechter, W.P., Massey, L.M., Ling, K., Kousik, C.S., Hammar, S.A., Tadmor, Y., Portnoy, V., Gur, A., Katzir, N., Guner, N., Davis, A., Hernandez, A.G., Wright, C.L., McGregor, C., Jarret, R.L., Xu, Y., Zhang, X., Wehner, T.C., Grumet, R., Levi, A., Fei, Z. 2019. Genome of ‘Charleston Gray’, the principal American watermelon cultivar, and genetic characterization of 1,365 accessions in the U.S. National Plant Germplasm System watermelon collection. Plant BiotechnologyJournal.

Branham, S., Wechter, W.P., Ling, K., Chanda, B., Massey, L.M., Zhao, G., Guner, N., Bello, M., Kabelka, E., Fei, Z., Levi, A. 2019b. QTL mapping of resistance to Fusarium oxysporum f. sp. niveum race 2 and Papaya ringspot virus in Citrullus amarus. Theoretical and Applied Genetics. 133:677-687.

Keinath, A.P., Dubose, V.B., Katawczik, M.L., Wechter, W.P. 2020. Identifying races of Fusarium oxysporum f. sp. niveum in South Carolina recovered from watermelon seedlings, plants, and field soil. Plant Disease. 104:2481-2488. RE.

Branham, S., Daley, J., Levi, A., Hassell, R., Wechter, W.P. 2020. QTL mapping and marker development for tolerance to sulfur phytotoxicity in melon (Cucumis melo). Frontiers in Plant Science. 11:1097-1105.

Katuuramu, D.N., Wechter, W.P., Washington, M., Horry, M.I., Cutulle, M.A., Jarret, R.L., Levi, A. 2020. Phenotypic diversity for root traits and identification of superior germplasm for root breeding in watermelon. HortScience. 55(8):12-72-1279.

Branham, S.E., Kousik, S., Mandal, M., Wechter, W.P. QTL mapping of resistance to powdery mildew race 1 in a recombinant inbred line population of melon. Plant Disease (ACCEPTED).

Toporek, S., Branham, S.E., Katawczik, M.L., Keinath, A.P., Wechter, W.P. 2021. QTL mapping of resistance to Pseudoperonospora cubensis clade 1, mating type 2, in Cucumis melo. Theoretical and Applied Genetics. (ACCEPTED)

Singh, G., Wechter, W.P., Framaha, B.S., Cutulle, M. 2021. Integration of halosulfuron and anaerobic soil disinfestation for weed control. Weed Technology. (ACCEPTED