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Thank you again for those of you attended one of my sessions. Here are links to my presentations. It will open PDF files on Google Drive. 1) Interactive grape disease management 2) Advanced topic in grape disease management: Fungicide resistance Please note that we will have more meetings coming up: 16 March 2018 Pruning workshop at Breaux Vineyards (Northern Virginia) 17 April 2018 Vineyard IPM workshop at Early Mountain Vineyards (Central Virginia) 6 June 2018 “Beginner’s” Grape Growing workshop Virginia Tech’s AHS Jr. Agricultural Research and Extension Center, Winchester VA We hope to see you there!

The label of Presidio has been changed, and unfortunately, the grape was removed from the list of hosts. This means that we no longer able to purchase Presidio to control grape downy mildew. If you already have it, it is still legally OK to use it for the grape, as long as you keep the original label. (and if you do, please make sure to mix with another mode of action such as mancozeb, captan, copper, since the active ingredient for Presidio is known to have the fungicide resistance issue, and required by the label to mix.)

Here's this year's handout for pruning time disease considerations  (this link opens Google Drive with this year's recommendation for trunk disease management). As I noted in this handout, the first line of defense against trunk diseases that may infect through pruning cut is a cultural control. Make sure to pick dates when you are expecting several days of dry weather. In this handout, I refer to Topsin-M as a choice of trunk disease management, especially for Botryosphaeria canker, which is very common in our area. The product has been transferred to a new company in 2017, and there are changes in the label. [Note: The US distributor is still the same (UPI), thus, I do not think it will affect where you can purchase the product.]  If you are using Topsin-M for pruning wound protection, please update your label.  You can download the new label by clicking this link  (will open Google Drive). If you are pruning, and wondering whether you can protect pruning woun...

Looks like we will likely to have another round of rain from Hurricane Irma sometimes next week. Just a reminder that we do not have any curative materials for Botrytis and other late season rots. In order to obtain better results, you need to protect your vines before the rain! Please see the previous post for disease management tips and the list of low PHI materials for each diseases. Also, it is very important to keep FRAC codes rotated!

At Winchester, night time temperature in recent few days is getting pretty low to the point that relative humidity during the night is close to 100%. In addition, we are looking at a thunderstorm forecast tonight that will bring high relative humidity. These conditions favor downy mildew development because downy mildew pathogen prefers to produce spores under dark, humid conditions. At this point, you do not need to worry about downy mildew infection on clusters; however, they can still infect leaves. Often time, you will initially see infection on the top of the canopy because younger leaves are more susceptible than older ones. Losing the top leaves and laterals are not a big deal; however, once the infection gets severe, it can defoliate many leaves rather quickly (as in the picture above), and that can affect maturing process. As usual, it is much better and easier to have a preventative program than trying to play the catch-up game. There are many good protective materials for do...

In a typical year, the fourth of July weekend is the time the critical period for cluster infection by downy mildew, powdery mildew, and black rot will end for many of us because it will be about 5-6 weeks after bloom. (Bloom this year was about 1-2 weeks ahead of typical years, so, this week maybe it for 2017.)  This critical time varies by varieties, but in general, 4 to 6 weeks and 3 to 4 weeks from bloom for V. vinifera and V. labrusca species, respectively.  After this critical period, you should be able to relax a bit because these pathogens are no longer able to cause disease on berries. Plus, powdery mildew tends to slow down because it is not very active under hot condition (> 90F). So, what’s next?  As usual, disease dynamics depends on environmental conditions, cultivars, and cultural practices you employ, but in general, this is the moment when you will be thinking about late season diseases such as Botrytis, ripe rot, bit...

As of today, it is about 10% bloom at our Chardonnay plots. Since bud break was about 2 weeks ahead of a typical year, things are moving along as we would expect. Of course, bloom in VA almost always has to happen in rain... As for bloom time disease management consideration, please refer to the previous post. From this point on, 4 to 5 weeks will be a critical period for management of downy mildew, powdery mildew, and black rot. Please make sure to keep your vines covered. Once again, providing a protection is much better and easier than playing a catch-up, especially if it comes to grape disease management in VA. You can use protective materials such as mancozeb, copper, and sulfur as your backbone, and add more specific (and often locally systemic) materials. Some of these materials have efficacy against multiple diseases (either by itself or through the combination of two materials). Examples are DMI, aka SI (FRAC = 3), e.g., Rally, tebuconazole, Mettle, etc. Inspire super is a...