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Grape Disease Management Update

Bloom and post-bloom are critical times for disease management in grapes. Temperatures and rainfall are generally favorable for pathogen development at this time, though conditions are not as wet as those observed last year. This is particularly true for grapes that are susceptible to powdery/downy mildews and Botrytis. The fruit are generally more susceptible to infection during bloom and shortly after. Make sure that you apply highly active materials during bloom and post-bloom for control of these pathogens. If you observe Botrytis following bloom, work with your local county agent to develop a fungicide resistance profile for your location — determine which fungicide classes still work at your location. By now, for most locations in Georgia where strobilurin fungicides (e.g. Abound, Pristine, etc.) have been utilized, activity is likely minimal to nonexistent for this class of chemistry for any or all of these pathogens. If using any strobilurin, tank mix with other fungicides with activity against these pathogens and others. See my previous post (6 April; Fungicide Suggestions for the Year) for suggested fungicides for this timeframe and as we progress through the season.

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About Phil Brannen

Phil Brannen is a Professor in the Plant Pathology Department at the University of Georgia. He attended the University of Georgia for his undergraduate degree in Plant Protection and Pest Management, where he also received an M.S. in Plant Pathology, followed by a Ph.D. in Plant Pathology from Auburn University. He has extensive experience with disease management programs in numerous cropping systems. He serves as the extension fruit pathologist for Georgia – conducting research and technology transfer for multiple fruit commodities. His efforts are directed towards developing IPM practices to solve disease issues and technology transfer of disease-management methods to commercial fruit producers. He also teaches the graduate level Field Pathology Course, the History of Plant Diseases and their Impact on Human Societies Course, team-teaches the IPM Course, coordinates the Viticulture and Enology in the Mediterranean Region Course (Cortona, Italy), and guest lectures in numerous other courses throughout the year.