I was feeling uncomfortable when the rain came around 6 pm, thinking "it came too early!", there were several rain events last night, but none of the rain did not last very long at Winchester area (< 1 hour around 6 pm, then about 20 min around 8:30pm, and < 1 hour around midnight). It was so windy that the relative humidity did not stay high, but stayed around 70%. Thus, this series of rain events was not creating a risk of fungal diseases. I'm more worry about damages done by wind. I hope your vineyards were OK.
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
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