(I'm still at a meeting, so, I will make it quick.) At Winchester, the series of rain started around 2 AM on this Monday (5/17/10), it was not a continuous rain, but we had frequent enough rain events during Monday, Tuesday, and this morning to keep the relative humidity high (>90%) until ~9:30 AM today. During Tuesday, there was a moment when the RH was little less than 90%, but it was still in high 80's. Thus, I would say this rain event accounted for about 55.5 hours of wetness and average temperature during this period was about 58F. Thus, it was long and warm enough for downy mildew, black rot, and Phomopsis. Some of us are expecting bloom very soon. Please remember that the critical time for downy, black rot, and powdery mildew berry infection is from bloom to 4-5 weeks after bloom.
Winchester area received precipitations from thunderstorms yesterday. It started around 3:30PM and lasted until 7:00PM. The actual amount of precipitation was not high (0.05 in) compared with other northern VA regions where a severe thunderstorm warning was issued, but since the ending part of the thunderstorm hit during the evening, the relative humidity was high (>90%) until 2 AM or so. Thus, it accounted for 11.5 hours of wetness with the average temperature of 73F. It was warm and long enough for Phomopsis, black rot, and downy mildew. We are still having chances of rain (40-60%) until Monday.
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