Grape Disease Risks: 8/12-8/19/2026

NEWA is an Agricultural Weather Station Network, and we are part of the team. Here is a snapshot from last week showing the number of days with risk for each disease: Ph = Phomopsis, PW = Powdery mildew, BR = Black rot, and DM = Downy mildew. N/A means there is no data or issues with the NEWA. I am waiting to hear back from the weather station company about fixing the one in Stafford. Note: Since we are out of the critical period for black rot and Phomopsis, you can ignore them.

There were more than four of the eight days with a risk of downy mildew infection in many locations in central to south VA. As we discussed in the previous virtual vineyard meetings, we still need to maintain our vines to ensure healthy canopies that support bud formation for next year, cane or spur selection, and winter survival. 

For detailed recommendations, please refer to the previous week’s posting.

Downy mildew forecast

Please click the table above to enlarge. Some Central VA locations show high probabilities of downy mildew in the coming week, most likely due to inoculum buildup from last week’s weather. (i.e., some of you have been experiencing high downy mildew risk weather for three weeks in a row.) I hope you can find a time to protect your vines before these events. Even if you are not bearing fruit this year, you still want your vines to keep healthy canopies so that they can survive the winter and produce healthy canes or spurs for next year.

The downy mildew forecasting effort is supported by the Virginia Wine Board.