Today, I observed downy mildew for the first time this year. It was on Lenoir vines in west Georgia, and this indicates that producers should be scouting for it throughout the state. In addition, if you have not already done so, I would consider incorporating highly efficacious materials such as Zampro, Revus, Ridomil Gold MZ (note the pre-harvest interval), etc. in spray programs as we move forward — especially under the wet conditions we have been observing. Downy mildew spores can infect within a few hours when leaves or fruit are wet. You definitely want to have good protection against this disease as we progress through the remainder of the season. Initial symptoms of downy mildew are “oil” spots on the upper leaf surface with white, fluffy spore formation on the leaf underside. See below for an example leaf from today.
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.