Although our bud break was about two weeks behind of a typical year, the wet and hot May pushed our vines forward rather quickly. Many people in northern VA are about to see blooms (our 3-year old young Chardonnay vines are trace bloom), and I am sure rest of regions are going through bloom by now. This means that many of us are in the critical time for cluster infections by downy mildew, powdery mildew, and black rot. Bloom time is also the critical period to prevent Botrytis, ripe rot, and bitter rot, because pathogens of these diseases can infect flower parts and develop symptoms later. With all the rains we observed, many people are concerned about downy mildew and black rot. In our vineyards, I did not see much sign of downy, but there are many leaves with black rot. It is probably because we did not have major downy mildew outbreaks in past three years. We do have materials with kick-back activities against downy (Ridomil products (FRAC=4), phosphite (FRAC=33, Pro...
Grape Disease Management Tips from Mizuho Nita (Grape Pathologist at Virginia Tech)