Professor of Plant Pathology
Research and Extension Vegetable Pathologist
Horticulture Program Team, Plant and Environmental Sciences Department, Coastal Research and Education Center
Office: Coastal REC, Charleston, SC
Ph.D. Plant Pathology
Cornell University 1988
M.S. Plant Pathology
Cornell University 1985
Michigan State University 1982
Vegetable Disease Unit of PLPA 4110/6110: Plant Disease Diagnosis, summers of odd years.
I am the state vegetable pathologist for South Carolina with a faculty appointment of 80% research and 20% Extension. The focus of my program is sustainable disease management for vegetable crops. Five M.Sc. and three Ph.D. students have graduated under my direction; currently I advise one M.S./Ph.D. student in the Plant and Environmental Sciences graduate program. I was the lead editor of the Compendium of Cucurbit Diseases and Pests, 2nd edition, APS Press, published 2017. In 2018 I was awarded the Godley-Snell Award for Excellence in Agricultural Research from Clemson University.
My research focuses on sustainable disease management for vegetables, including the management, ecology, and epidemiology of fungi, oomycetes (water molds), and other plant pathogens. My area of expertise is Stagonosporopsis citrulli (formerly Didymella bryoniae), the fungus that causes gummy stem blight on cucurbits. Crops include the cucurbit crops watermelon, muskmelon, zucchini, and cucumber; eggplant and tomato; the leafy brassicas mustard, turnip, and collard greens; and beets. Successful management strategies should be effective, economical, and environmentally responsible.
Current research projects include epidemiology of gummy stem blight; resistance to fungicides in fungal and oomycete pathogens; fungicide efficacy against gummy stem blight and Fusarium wilt on watermelon and downy mildew on cucumber and zucchini squash; ecology and management of Pythium spp. on cucurbits; and management of Cercospora leaf spot on beet.
Extension and Outreach
The goal of my Extension program is to help people solve problems with their plants. The primary audience is small and large vegetable growers in South Carolina. Urban problems in the greater Charleston area also are addressed. Currently, my graduate students and I are conducting a survey of foliar diseases on muskmelon and Pythium species occurring on cucurbits.
My Extension program includes grower, agent, Master Gardener, and home gardener education; vegetable disease management recommendations, including fungicides and cultural practices; vegetable disease diagnosis; and on-farm research trials. I contribute yearly to the Southeastern U.S. Vegetable Crop Handbook. Since 2014 I am a tri-weekly gardening columnist for The Post and Courier newspaper, Charleston, SC.
Refereed Journal Articles
1. Keinath, A. P., Wechter, W. P., Rutter, W. B., and 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 Dis. 103:103:1383-1390.
2. Rennberger, G., Gerard, P., and Keinath, A. P. 2019. Factors Influencing the occurrence of foliar pathogens in commercial watermelon fields in South Carolina based on stratified cluster sampling. Plant Dis. 103:484-494.
3. Keinath, A. P., Coolong, T. W., Lanier, J. D., and Ji, P. 2019. Managing Fusarium wilt of watermelon with delayed transplanting and cultivar resistance. Plant Dis. 103:44-50.
4. Rennberger, G., Gerard, P., and Keinath, A. P. 2018. Occurrence of foliar pathogens of watermelon on commercial farms in South Carolina estimated with stratified cluster sampling. Plant Dis. 102:2285-2295. DOI:10.1094/PDIS-03-18-0468-RE
5. Keinath, A. P., and Agudelo, P. A. 2018. Retention of resistance to Fusarium oxysporum f. sp. niveum in cucurbit rootstocks infected by Meloidogyne incognita. Plant Dis. 102:1820-1827.
6. Rennberger, G., and Keinath, A. P. 2018. Susceptibility of fourteen new cucurbit species to gummy stem blight caused by Stagonosporopsis citrulli under field conditions. Plant Dis. 102:1365-1375.
7. Neufeld, K. N., Keinath, A. P., and Ojiambo, P. S. 2018. Evaluation of a model for predicting the daily infection risk of squash and cantaloupe by Pseudoperonospora cubensis. Plant Dis. 102:855-862.
8. Keinath, A. P. 2018. Minimizing yield and quality losses in watermelon with multi-site and strobilurin fungicides effective against foliar and fruit anthracnose. Crop Prot. 106:72-78.
9. Neufeld, K. N., Keinath, A. P., Gugino, B. K., McGrath, M. T., Sikora, E. J., Miller, S. A., Ivey, M. L., Langston, D. B., Dutta, B., Keever, T., Sims, A., and Ojiambo, P. S. 2018. Predicting the risk of cucurbit downy mildew in the eastern United States using an integrated aerobiological model. Int. J. Biometeorol. 62:655-668. DOI:10.1007/s00484-017-1474-2
10. Keinath, A. P., and DuBose, V. B. 2017. Disinfectant treatments that reduce transmission of Stagonosporopsis citrulli during cucurbit grafting. Plant Dis. 101:1895-1902.
11. Keinath, A. P., and DuBose, V. B. 2017. Management of southern blight on tomato with SDHI fungicides. Crop Prot. 101:29-34.
12. Neufeld, K. N., Keinath, A. P., and Ojiambo, P. S. 2017. A model to predict the risk of infection of cucumber by Pseudoperonospora cubensis. Microb. Risk Anal. 6:21-30.
13. Rennberger, G., Keinath, A. P., and Hess, M. 2017. Correlation of trichome density and length and polyphenol fluorescence with susceptibility of five cucurbits to Didymella bryoniae. J. Plant Dis. Prot. 124:313-318. DOI:10.1007/S41348-016-0050-z
14. Sui, X., Zheng, Y., Li, R., Padmanabhan, C., Tian, T., Groth-Helms, D., Keinath, A. P., Fei, Z., Wu, Z., and Ling, K.-S. 2017. Molecular and biological characterization of Tomato mottle mosaic virus and development of RT-PCR detection. Plant Dis. 101:704-711.
15. Wechter, W. P., McMillan, M. M., Keinath, A. P., Smith, J. P., and Farnham, M. W. 2016. â€˜Carolina Broadleafâ€™ mustard green (Brassica juncea) resistant to the bacterial leaf blight pathogen Pseudomonas cannabina pv. alisalensis. HortScience 51:1062-1064.
16. Keinath, A. P., Wechter, W. P., and Farnham, M. W. 2016. Suppression of bacterial blight on mustard greens with host plant resistance and acibenzolar-S-methyl. Plant Dis. 100:1921-1926.
17. Keinath, A. P. 2016. Polyoxin D and other biopesticides reduce gummy stem blight but not anthracnose on melon seedlings. Plant Health Prog. 17:177-181. doi:10.1094/PHP-RS-16-0025
18. Keinath, A. P. 2016. Utility of a cucumber plant bioassay to assess fungicide sensitivity in Pseudoperonospora cubensis. Plant Dis. 100:490-499.
19. Keinath, A. P. 2015. Efficacy of fungicides against powdery mildew on watermelon caused by Podosphaera xanthii. Crop Prot. 75:70-76.
20. Keinath, A. P. 2015. Baseline sensitivity of Didymella bryoniae to cyprodinil and fludioxonil and field efficacy of these fungicides against isolates resistant to pyraclostrobin and boscalid. Plant Dis. 99:815-822.
21. Keinath, A. P. 2014. Reproduction of Didymella bryoniae on nine species of cucurbits under field conditions. Plant Dis. 98:1379-1386.
22. Keinath, A. P., and Hassell, R. L. 2014. Suppression of Fusarium wilt caused by Fusarium oxysporum f. sp. niveum race 2 on grafted triploid watermelon. Plant Dis. 98:1326-1332.
23. Keinath, A. P., and Hassell, R. L. 2014. Control of Fusarium wilt of watermelon by grafting onto bottlegourd or interspecific hybrid squash despite colonization of rootstocks by Fusarium. Plant Dis. 98:255-266.
24. Keinath, A. P. 2014. Differential susceptibility of nine cucurbit species to the foliar blight and crown canker phases of gummy stem blight. Plant Dis. 98:247-254.
25. Ling, K.-S., Levi, A., Adkins, S., Kousik, C. S., Miller, G., Hassell, R., and Keinath, A. 2013. Development and field evaluation of multiple virus virus-resistant bottle gourd (Lagenaria siceraria). Plant Dis. 97:1057-1062.
26. Keinath, A. P. 2013. Susceptibility of cucurbit rootstocks to Didymella bryoniae and control of gummy stem blight on grafted watermelon seedlings with fungicides. Plant Dis. 97:1018-1024.
27. Keinath, A. P., and Hansen, Z. R. 2013. Isolates of Didymella bryoniae from South Carolina remain sensitive to DMI fungicides despite multi-year exposure. J. Phytopathol. 161:315-323.
28. Hansen, Z. R., and Keinath, A. P. 2013. Increased pepper yields following incorporation of biofumigation cover crops and the effects on soilborne pathogen populations and pepper diseases. Appl. Soil Ecol. 63:67-77.
29. Wechter, W. P., Keinath, A. P., McMillan, M., Smith, J. P., and Farnham, M. W. 2013. Expression of bacterial blight resistance in Brassica leafy greens under field conditions and inheritance of resistance in a Brassica juncea source. Plant Dis. 97:131-137.
30. Keinath, A. P., and DuBose, V. B. 2012. Controlling powdery mildew on cucurbit rootstock seedlings in the greenhouse with fungicides and biofungicides. Crop Prot. 42:338-344.
31. Keinath, A. P. 2012. Differential sensitivity to boscalid in conidia and ascospores of Didymella bryoniae and frequency of boscalid-insensitive isolates in South Carolina. Plant Dis. 96:228-234.
32. Keinath, A. P., and Kousik, C.S. 2011. Sensitivity of isolates of Phytophthora capsici from the eastern United States to fluopicolide. Plant Dis. 95:1414-1419.
33. Farnham, M. W., Keinath, A. P., and Grusak, M. A. 2011. Mineral concentration of broccoli florets in relation to year of cultivar release. Crop Sci. 51:2721-2727.
34. Ling, K.-S., Wechter, W. P., Walcott, R. R., and Keinath, A. P. 2011. Development of a real-time RT-PCR assay for Squash mosaic virus useful for broad spectrum detection of various serotypes and its incorporation into a multiplex seed health assay. J. Phytopathol. 159:649-656.
35. Levi, A., Thies, J. A., Simmons, A. M., Harrison, H., Hassell, R., and Keinath, A. 2011. USVL-220, a novel watermelon breeding line. HortScience 46:135â€“138.
36. Ling, K.-S., Wechter, W. P., Somai, B. M., Walcott, R. R., and Keinath, A. P. 2010. 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.
37. Keinath, A. P., Hassell, R. L., Everts, K. L., and Zhou, X.-G. 2010. Cover crops of hybrid common vetch reduce Fusarium wilt of seedless watermelon in the eastern United States. Online. Plant Health Progress. doi:10.1094/PHP-2010-0914-01-RS
38. Keinath, A. P. 2010. Potassium phosphite mixed with other fungicides reduces yield loss to downy mildew on collard. Online. Plant Health Progress. doi:10.1094/PHP-2010-0823-01-RS
39. Njoroge, S.M.C., Toler, J.E. and Keinath, A.P. 2010. Soil solarization on populations of Pythium spp., fluorescent Pseudomonas, and damping-off of broccoli and cucumber. Int. J. Veg. Sci. 16:15-31.
Compendium of Cucurbit Diseases and Pests, Second Edition
Gummy Stem Blight on Watermelon (video)
Watermelon Fungicide Guide
The Post and Courier gardening columns