UGA Extension Viticulture Blog

Here Comes the Rain — Diseases Too

We have had pretty dry weather recently, but the rainfall of late and predictions for more storms next week will increase the likelihood of downy mildew onset — as well as other fungal diseases of wine grapes.  We are still within a critical stage for cluster infections by downy mildew and other diseases.  Scout aggressively for mildews, particularly downy mildew.  If you see downy mildew in your vineyard, pull the trigger on a Ridomil Gold MZ application; in general, you should still be within the preharvest interval for this fungicide at this time.  Try to use this fungicide only once per season in an effort to prevent resistance from developing.  After the Ridomil Gold MZ application, assuming again that downy mildew is present and rain continues, I would incorporate rotations of the more efficacious fungicides for downy mildew management (Revus, Zampro, Revus Top, Prophyt + Captan, or Prophyt + Ranman, etc.).  When conditions are dry, apply fungicides on a 10-14 day schedule; when wet, go to a 7-10 day schedule. Follow all label directions, and contact your local county agent should you have questions relative disease management or any other grape management topics.

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About pbrannen

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.