Grape Disease Risks 5/3 – 5/10/2023 (and tomorrow’s virtual meeting)

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. This information was made available through the Wine Board-funded Sentinel Vineyard project. The downy mildew model is back again (except for the Leesburg station… I will report it to them. Based on the risk output from the nearby weather station, the risk of downy mildew was most likely zero at the location, though.)

Rain events passed across the state, resulting in a few days with disease risks. In some areas, the temperature during the rain event was low enough not to result in a risk event, but we have 2-3 days with risks across the state. Downy mildew risk was high for three and four days out of seven at Winchester and Charles City, respectively. (Last week, I mentioned a dry week, which ended up very wet in our area, so I won’t mention the forecast this time. ;))

Here’s a link to early-season grape disease management reminders. 

The image above is just a summary of the past seven days. Please visit to obtain more detailed information. You can check daily weather data and disease and insect pest model results, including forecasted risks. We paid the annual fee so that growers in Virginia could freely access NEWA.

The risk information above is just output from the model to help you understand what happened. However, preparing your sprays to protect your vines would be best. One way to use this information is to adjust your spray intervals. If you see many days with disease risk(s), you may need to shorten your spray interval, or if you missed a material for downy mildew or black rot, you might wish to spray material(s) with kick-back activity. Or you may want to extend your spray interval, if you have not seen much risks as we have been experiencing this year. 

It is essential to understand that the spray decision must be based not only on the weather condition but also on the cultivar and history of the disease(s) in your vineyard.

2023 Virtual Viticulture Meeting

If you have not, please use the form below to register. (i.e., if you already registered, you do not need to do it again.) All we need is your email address so that we can send you a reminder. It will provide you with a Zoom link after completion. We will use the same link for all six meetings, so make sure to copy and paste it into your calendar!

We are looking forward to seeing you via Zoom!

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