Here are links to the 2021 edition of Pest Management Guides. Unlike the past years, all the crops are combined together. (i.e., I cannot separate the grape section.) Once you get to the site, click "PDF", then "Preview", and it will open a new window. Then you need to click "Download Version" to download the file to your computer. Once the document is downloaded, you can search the document to find "grapes".
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...
A bit confusing but I got it.
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