Grape Disease Risk Summary 6/22-6/29/2022

Here’s a snapshot from the last week, showing the number of days with the risk of each disease: Ph = Phomopsis, PW = Powdery mildew, BR = Black rot, and DM = Downy mildew.

The image above is just a summary. Please visit https://newa.cornell.edu/ to obtain more detailed information. You can check daily weather data as well as disease and insect pest model results including forecasted risks. We paid the annual fee so that growers in Virginia can freely access NEWA. Please take advantage of the resources. This information was made available through Wine Board-funded the Sentinel Vineyard project. We obtained NEWA weather stations that have been installed throughout the state.

More than a few days with downy mildew risks were observed in nearly all stations in the past 7 days. In addition, it looks like we are expecting a rainy week starting next Tuesday. If you have not, please consider protecting your vines with downy mildew material(s). If you saw more than 2 inches of rain, it is probably a good idea to mix a phosphonate (i.e., a “phos acid”, such as Prophyt or Phostrol) for downy mildew and a DMI (e.g., Rally) for black rot to your next spray.

Many of our vines are nearly done with the critical period for downy mildew, powdery mildew, and black rot cluster infection (i.e., bloom to ~6 weeks after bloom). Once you are done with the critical period, you will focus on powdery and downy mildew until veraison. You can find specific materials information in this post (mid-season disease management), this post (VVA presentation), or this one (bloom time reminders).

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