At Winchester, we had rain from 11:50am to 2:20pm (0.12 in) with starting and ending temperature of 62.3 and 67.8F, respectively. Relative humidity dropped soon after the rain and still declining at 5pm and the wind was constantly blowing at 5-10 mph, thus, leaves are probably dried one hour or so after the rain. (If the leafwetness measurement is not available, I use RH>90% as an indicator for the leafwetness after the rain.) Three hours or so was not enough for Phomopsis infection, but it was warm enough for powdery mildew ascospore discharge.Yesterday (4/30/09), we took an advantage of a calm cloudy day and applied our first fungicide application (mancozeb 3 lb/A + sulfur 3 lb/A). Primary target at this point is Phomopsis and Powdery mildew.
Although it was either raining or overcast, average temperature in the past few days were in 50's and 60's, and grape were moving its growth stage. About 70% of our Chardonnay was 3-inch stage, and Cabernet sauvignon was about 50% with 1-2 inch stage (still variable, some are just after bud break).
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