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Prepare for a potential rain event for this weekend.


Looks like a tropical storm Marco is moving westward, but Laura may hit our areas during this weekend. The current forecast shows (opens a new window with a link to Weather.com) potential movement to Virginia and surrounding states around this Saturday (8/29). Many white cultivars will be either ready to pick or getting very close to harvest, and red cultivars may have several weeks to go, depends on where you are what you grow.

At this point in the season, the target diseases are late-season fruit rots (Botrytis, ripe rot, bitter rot, etc.) and downy mildew (on leaves).

For whites, it may be a decision of when to pick, but not what to spray. If you decided to wait until the storm is over, there are several materials with a very short PHI that you may want to consider, such as Oso/Ph-D or Elevate for Botrytis and a phos acid for downy mildew. FYI: when we tested in the field, Oso plus Double Nickel combination worked well against sour rot.

For reds, it will depend on when and what you have sprayed recently. As noted in the previous posts and meetings, it may not be a good idea to spray captan, sulfur, and copper near harvest due to their potential negative impacts on the fermentation and wine quality. However, you probably need to assess the situation at both your vineyard and winery. 

The links here are the presentation slides from the last viticulture meeting that covers some of the diseases mentioned above and a list of short PHI materials for Botrytis, powdery mildew, and downy mildew, which may help you decide what to do.


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