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. At this point, you can ignore Phomopsis and black rot since Phomopsis should be done with their spore production, and clusters are resistant to black rot infection. This information was made available through the Wine Board-funded Sentinel Vineyard project. As noted above, this will be the last disease risk post for the season. (Let me know if you think I need to extend it for a few more weeks.)
Now we have two consecutive wet week after three weeks (for the Central and Southern VA) and after almost entire season (for the Northern VA). At Northern VA, we may have a whole week of rain, which we needed, but at the same time, it may interfere with harvest… At this point what we need to take care of are downy mildew (on leaves) and late-season rots. Remember that your spray decision should not solely rely on weather conditions. It is crucial to consider factors such as the cultivar and the disease history in your vineyard. Please see the slide set from our previous meeting discussing late-season rot management. Some products have a relatively long PHI (e.g., Ranman’s PHI is 30 days). This post contains the list of fungicides with short PHIs. Make sure to read the label or refer to our PMG.
The image above summarizes the past seven days, aiding your understanding of recent events. However, the best action is proactively safeguarding your vines. For more comprehensive information, please visit https://newa.cornell.edu/, where you can access detailed daily weather data and disease and insect pest model results, including forecasted risks. We have covered the annual fee to ensure free access for growers in Virginia to the NEWA platform.
Sentinel Vineyard report #2