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Time to Pull out the Big Guns

I think most producers are fully aware that recent rainfall events will increase disease levels in wine grapes.  I am particularly concerned about fruit rots and downy mildew.  In particular, more active materials for downy mildew are needed at this time.  Though the contact materials such as Captan and Mancozeb are good materials, I think it is time to bring in systemic materials as well — at least until we have drier conditions. If I were growing grapes commercially, I would consider use of Ridomil Gold MZ as soon as I could get back into the vineyard; this may be a little earlier trigger than desired, but I think it is warranted with the current conditions in the field.  Ridomil has good kickback activity, and I hope it will take out some infections that may have occurred in the last 24-48 hours.  I would then rotate in the more active materials such as Zampro, Revus (or Revus Top), Ranman + Prophyt, Prophyt + Captan etc. — incorporating the most active materials and using as many fungicide classes as possible for resistance management.  Again, these are downy mildew active materials and you have to cover the rots (Botrytis, black rot, ripe rot, etc.) and powdery mildew as well with other fungicides.  As always, contact your local county agent should you have questions or need additional information.

Downy Mildew Fungicides

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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.