I've learned that southern and central regions already seeing bud breaks among early varieties. Since early season protection (1-3 inches, no later than 3-5 inches) is a critical timing for Phomopsis management, I uploaded "Note on Phomopsis" which is a part of topics I will be presenting at the next vineyard meeting (4/29/2009). I'm planning to add information about black rot and powdery mildew in the near future to this note, but in the mean time, please take a look at this draft, especially if you have issues with Phomopsis in your vineyard. Hopefully, it will help your decision making.
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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