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 studied include the cucurbits watermelon, muskmelon, cucumber, and zucchini; 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 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. In 2019-2021 I will be conducting a survey of foliar diseases on cantaloupe in South Carolina.
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 plant problems in the greater Charleston area also are addressed.
My Extension outreach 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.
1. Keinath, A. P. 2019. Integrated management of downy mildew on slicing cucumber with fungicides and host resistance but not trellising. Plant Dis. 103:2592-2598.
2. Keinath, A. P., Miller, S. A., and Smart, C. D. 2019. Response of Pseudoperonospora cubensis to preventative fungicide applications varies by state and year. Plant Health Progress 20:142-146.
3. 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. 103:1383-1390.
4. 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.
5. 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.
6. 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)
7. 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. (DOI:10.1094/PDIS-12-17-1916-RE)
8. 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. DOI:10.1094/PDIS-12-17-1953-RE
9. 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. DOI:10.1094/PDIS-07-17-1046-RE
10. 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.
11. Keinath, A. P., Ling, K.-S., Adkins, S., Hasegawa, D. K., Simmons, A. M., Hoak, S., Mellinger, H. C., and Kousik, C. S. 2018. First report of cucurbit leaf crumple virus infecting three cucurbit crops in South Carolina. Plant Health Progress 19:322-323.
12. Keinath, A. P., Rennberger, G., and Kousik, C. S. 2018. First report of resistance to boscalid in Podosphaera xanthii, cucurbit powdery mildew, in South Carolina. Plant Health Progress 19:220-221.
13. Rennberger, G., Kousik, C. S., and Keinath, A. P. 2018. First report of powdery mildew on Cucumis zambianus, Cucurbita digitata and Melothria scabra caused by Podosphaera xanthii in the United States. Plant Dis. 102:246. DOI:10.1094/PDIS-06-17-0916-PDN
14. 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
15. Keinath, A. P., and DuBose, V. B. 2017. Disinfectant treatments that reduce transmission of Stagonosporopsis citrulli during cucurbit grafting. Plant Dis. 101:1895-1902.
16. Keinath, A. P., and DuBose, V. B. 2017. Management of southern blight on tomato with SDHI fungicides. Crop Prot. 101:29-34. DOI:10.1016/j.cropro.2017.07.013
17. 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.
18. 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
19. 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.
20. Rennberger, G., Dowling, M., Keinath, A. P., and Schnabel, G. 2017. First report of root rot caused by Pythium ultimum on Acanthosicyos horridus (Cucurbitaceae). Plant Dis. 101:258.
21. Wechter, W. P., McMillan, M. M., Keinath, A. P., Smith, J. P., and Farnham, M. W. 2016. ‘Carolina Broadleaf’ mustard green (Brassica juncea) resistant to the bacterial leaf blight pathogen Pseudomonas cannabina pv. alisalensis. HortScience 51:1062-1064.
22. 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.
23. 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
24. Keinath, A. P. 2016. Utility of a cucumber plant bioassay to assess fungicide sensitivity in Pseudoperonospora cubensis. Plant Dis. 100:490-499.
25. Keinath, A. P. 2015. Efficacy of fungicides against powdery mildew on watermelon caused by Podosphaera xanthii. Crop Prot. 75:70-76.
26. Keinath, A. P. 2015. Identification of races of Colletotrichum orbiculare on muskmelon in South Carolina. Online. Plant Health Progress. DOI:10.1094/PHP-BR-15-0004.
27. 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.
28. Keinath, A. P. 2015. Evaluating fungicide sensitivity of P. capsici in vitro. Protocol 05-02.1 in: Laboratory Protocols for Phytophthora Species, K. L. Ivors, ed. APS Press. Online. doi:10.1094/9780890544969.05.02.1
Compendium of Cucurbit Diseases and Pests, Second Edition
Gummy Stem Blight on Watermelon (video)
Watermelon Fungicide Guide
The Post and Courier gardening columns