UGA Extension Viticulture Blog

Powdery Mildew Management Information for Next Year

This information is a out of place relative the season, but I want to share it with you while it is fresh on my mind.  Despite a wet year, some producers have experienced significant powdery mildew issues this year — some on the clusters. Powdery mildew contributes to poor grape development, but it also contributes to subsequent invasion by other rots as well. When observed, the lack of control means that one of two things happened: (1) poor application timing and/or coverage with the appropriate fungicides, or (2) resistance development by the powdery mildew fungus.  The slide set below (see link) was presented at a meeting I attended a couple of weeks ago.  Brent Warneke, a graduate student at Oregon State, conducted the research, and he shipped this to me with his permission to share it ahead of publication. In his studies, Fluopyram (Luna fungicides), Quinoxyfen (Quintec), and Trifloxystrobin (Flint) were all effective at controlling mildew, but the timing of efficacious products at the 50% bloom and late bloom timeframes were proven to be of exceptional value for grape powdery mildew management.  In these studies, Fluopyram was particularly effective. I would be careful about trusting Flint if you have utilized other strobilurins over time, but I would recommend use of Fluopyram for these critical sprays next year. He used sulfur before and after the bloom sprays, and his management of mildew was excellent.  These presentations may be a bit technical for some, but I think you can glean the pertinent information of importance for your spray programs. We will discuss this information in meetings, but again, take a look at it as you have time.

APS 2017 Brent Warneke Presentation