Professor of Plant Pathology
Research and Extension Vegetable Pathologist
Horticulture Program Team, Plant and Environmental Sciences Department, Coastal Research and Education
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. My faculty appointment is divided into 80% research and 20% extension. The focus of my program is sustainable disease management for vegetable crops. I have served as a major advisor for five M.Sc. and two Ph.D. students (graduated); currently I advise one Ph.D. student and co-advise another. I am the lead editor of the Compendium of Cucurbit Diseases and Pests, 2nd edition, APS PRESS, expected publication date of July 2017.
My research focuses on sustainable disease management for vegetables, including the management, ecology, and epidemiology of fungi, Oomycetes, and bacteria on cucurbits, leafy brassicas, and other vegetables. My area of expertise is Stagonosporopsis citrulli (formerly Didymella bryoniae), the fungus that causes gummy stem blight on cucurbits.
Recent research crops include cucurbits, such as watermelon, summer squash, butternut squash, cucumber, and muskmelon; brassicas, such as mustard, turnip, and collard greens; and tomatoes.
Recent research projects include epidemiology of gummy stem blight; fungicide efficacy against Southern blight of tomato, gummy stem blight, anthracnose, and powdery mildew on watermelon, and downy mildew on squash; resistance to fungicides in fungal pathogens; grafting , planting date modification, and other cultural practices to manage Fusarium wilt of watermelon; and combining host plant resistance and a resistance activator to manage bacterial blight of leafy brassica greens.
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. Currently, my graduate student and I are conducting a survey of foliar diseases on watermelon.
Refereed Journal Articles
1. 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: (in press).
2. 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.
3. 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.
4. 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
5. Keinath, A. P. 2016. Utility of a cucumber plant bioassay to assess fungicide sensitivity in Pseudoperonospora cubensis. Plant Dis. 100:490-499.
6. Keinath, A. P. 2015. Efficacy of fungicides against powdery mildew on watermelon caused by Podosphaera xanthii. Crop Prot. 75:70-76.
7. 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.
8. Keinath, A. P. 2014. Reproduction of Didymella bryoniae on nine species of cucurbits under field conditions. Plant Dis. 98:1379-1386.
9. 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.
10. 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.
11. 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.
12. 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.
13. 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.
14. 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.
15. 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.
16. 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.
17. 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.
18. 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.
19. 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.
20. 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.
21. 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.
22. Levi, A., Thies, J. A., Simmons, A. M., Harrison, H., Hassell, R., and Keinath, A. 2011. USVL-220, a novel watermelon breeding line. HortScience 46:135–138.
23. 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.
24. 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.
25. 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.
26. 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.
27. Keinath, A. P. 2009. Sensitivity to azoxystrobin in Didymella bryoniae isolates collected before and after field use of strobilurin fungicides. Pest Manag. Sci. 65:1090–1096.
28. Ha, Y., Fessehaie, A., Ling, K. S., Wechter, W. P., Keinath, A. P., and Walcott R. R. 2009. 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.
29. Keinath, A. P. 2008. Survival of Didymella bryoniae in infested muskmelon crowns in South Carolina. Plant Dis. 92:1223-1228.
30. Njoroge, S. M. C., Riley, M. B., and Keinath, A. P. 2008. Effect of incorporation of Brassica spp. residues on population densities of soilborne microorganisms and on damping-off and Fusarium wilt of watermelon. Plant Dis. 92: 287-294.
Review Articles and Refereed Book Chapters
1. Holmes, G. J., Ojiambo, P. S., Hausbeck, M. K., Quesada-Ocampo, L., and Keinath, A. P. 2015. Resurgence of cucurbit downy mildew in the United States: A watershed event for research and extension. Plant Dis. 99:428-441.
2. Keinath, A. P. 2013. Diagnostic guide for gummy stem blight and black rot on cucurbits. Online. Plant Health Progress. doi:10.1094/PHP-2013-1024-01-DG
3. Keinath, A. 2011. From native plants in Central Europe to cultivated crops worldwide: The emergence of Didymella bryoniae as a cucurbit pathogen. HortScience 46:532-535.
4. Ojiambo, P. S., Holmes, G. J., Britton, W., et al., 2011. Cucurbit downy mildew ipmPIPE: A next generation web-based interactive tool for disease management and extension outreach. Online. Plant Health Progress. doi:10.1094/PHP-2011-0411-01-RV
Other Refereed Publications
1. 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
2. Wechter, W. P., Keinath, A. P., Smith, J. P., Farnham, M. W., Bull, C. T., and Schofield, D. A. 2014. First report of bacterial leaf on mustard greens (Brassica juncea) caused by Pseudomonas cannabina pv. alisalensis in Mississippi. Plant Dis. 98:1151.
3. Farnham, M. W., Keinath, A. P., and Grusak, M. A. 2013. Response to the Letter to the Editor of Crop Science from Donald R. Davis Regarding Our Research Article Entitled “Mineral Concentration of Broccoli Florets in Relation to Year of Cultivar Release” Published in Crop Science (2011 51:2721–2727). Crop Sci. 53:1830-1831.
4. Stevenson, K. L., Keinath, A. P., Thomas, A., Langston, Jr., D. B., Roberts, P. D., Hochmuth, R. C., and Thornton, A. C. 2012. Boscalid insensitivity documented in Didymella bryoniae isolated from watermelon in Florida and North Carolina. Online. Plant Health Progress. doi:10.1094/PHP-2012-0518-01-BR
5. Wechter, W. P., Keinath, A. P., Farnham, M. W., and Smith, J. P. 2010. First report of bacterial leaf blight on broccoli and cabbage caused by Pseudomonas syringae pv. alisalensis in South Carolina. Plant Dis. 94:132.
6. Kousik, C. S., and Keinath, A. P. 2008. First report of insensitivity to cyazofamid among isolates of Phytophthora capsici from the southeastern United States. Plant Dis. 92:979.
7. Ling, K. S., Kousik, C. S., and Keinath, A. P. 2008. First report of Southern blight on bottle gourd (Lagenaria siceraria) caused by Sclerotium rolfsii in South Carolina. Plant Dis. 92:656.
8. Wechter, W. P., Keinath, A. P., Smith, J. P., and Farnham, M. W. 2008. First report of severe outbreaks of bacterial leaf spot of leafy brassica greens caused by Xanthomonas campestris pv. campestris in South Carolina. Plant Dis. 92:1134.
1. Keinath, A. P., and Miller, G. A. 2017 (rev). Watermelon Spray Guide for 2016. Clemson Univ. Extension HOR01.
2. Keinath, A. P., and Rennberger, G. 2017. Powdery Mildew on Watermelon. Clemson Univ. Extension HOR02.
3. Keinath, A. P. 2015 (rev). Cucurbit Downy Mildew Management for 2015. Clemson Univ. Extension Information Leaflet 90 (www.clemson.edu/psapublishing/Pages/Plntpath/IL90.pdf).
4. Kemble, J. M., Lewis Ivey, M. L., Jennings, K. M., and Walgenbach, J. F., ed. 2016 (rev). Southeastern U.S. Vegetable Crop Handbook. (Contributor). (www.thepacker.com/grower/2015-southeastern-us-vegetable-crop-handbook ).
5. Keinath, A. P. 2014. Susceptibility of Seventeen Cucurbit Crops to Gummy Stem Blight. Agricultural News, May 2014, pp. 10-11. Cornell Cooperative Extension - Suffolk County, NY.
6. Keinath, A. P. 2012 (rev). Managing Phytophthora Blight on Squash and Pepper. Clemson Univ. Extension Info. Leaflet 85. (www.clemson.edu/psapublishing/Pages/Plntpath/IL85.pdf).
7. Keinath, A. P. 2012. Controlling Bacterial Spot on Tomato and Pepper. Clemson Univ. Extension Info. Leaflet 91. (www.clemson.edu/psapublishing/Pages/Plntpath/IL91.pdf).
8. Francis, R., and Keinath, A. 2010. Biofungicides and Chemicals for Managing Diseases in Organic Vegetable Production. Clemson Cooperative Extension Information Leaflet 88. (http://www.clemson.edu/psapublishing/PAGES/PLNTPATH/IL88.pdf).
9. Polomski, R. F., Hassell, R. L., and Keinath, A. P. Revised 2008. Home Vegetable Gardening. Clemson University Extension Circular 570. 145 pp.
10. Keinath, A. 2007. Santa Barbara—A Superior Salvia. SC Nurseryman, July/Aug. 2007, p. 45.
11. Keinath, A. P., Willliamson, M. R., Polomski, B., and Miller, R. W. 2007. Basic Plant Pathology. Chapter 7 in: The South Carolina Master Gardener Training Manual, Clemson Univ.
12. Polomski, B., and Keinath, A. P. 2007. Herbaceous Ornamental Plants: Annuals, Bulbs, and Perennials. Chapter 14 in: The SC Master Gardener Training Manual, Clemson Univ.