At Winchester, we had light rain events during the night of 6/12/09, but it was short events and the relative humidity was low (80% or so), thus it probably did not promote any infections. However, we are experiencing continuing favorable nights for downy mildew sporulation (average T>55F, high RH (80-100%)) for 10 days now. Yesterday, we conducted a formal disease assessment, and observed first incidence of powdery mildew for this season. We had plenty of infection events in last two months, so it was not surprising. At this point, it is a trace level of infection on untreated vines. Downy mildew was the major disease so far. We had up to 40% incidence on untreated vines. Next runner-up was black rot. It varies vine to vine, but some of vine had 10-15% incidence. Phomopsis was omnipresent as I expected from early May rain falls, but severity was low overall. We will examine diseases again in the near future, and I will update as the season goes. Here is downy mildew ga...
We have seen some damage due to climbing cutworms on Chardonnay. Since I'm not an entomologist, I'll refer to Dr. Pfeiffer's page for the description of the insect. Virginia Tech's grape diseases and insects in vineyards has spray recommendations for cutworms. Some chemicals listed in the guideline can be harmful to beneficial insects such as bees which are very active right now with apple blossoms. Please refer to the label before you apply it. When you are in doubt, please consult local extension agents.
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