Virginia Grape Disease Updates

Our 5-yr old Chardonnay is still in the mitten stage, only a few broke buds.  At least we do not see the risk of frost in the 10-day forecast... Once they broke buds, the first disease to be considered is Phomopsis.  It is because a) Phomopsis produce spores from previously infected canes, cordons, and trunks, b) the spores are active even in 40's, and c) young leaves and clusters are susceptible to infection.  The best approach is use of Mancozeb, captan, or Zirum as a protective application.  QoI fungicides such as Abound and Pristine works too, but you want to keep them for later in the season.

Some of northern VA growers contacted us about splitting of the trunks and cordons which became apparent in the last few weeks.  Although the cold injury model showed that temperature we experienced were below the threshold temperature (i.e., the buds should be safe in many cases), the cold winter then a few days of warmth followed by another cold temperature probably caused some of vines to show more or less like "Southwest injury" on trunks and cordons.  If you have these suffering vines, you would probably think about re-training damaged cordon or trunk.  If you decided to do, please keep in your mind that the big wound can invite various vascular/trunk pathogens such as Esca and Botryosphaeria.  These disease may not damage the vines in a short time, but it can shorten the life of the vine.  As I noted in my trunk disease management page , there are few options to provide protections on these wounds. The bottom line is that you should pick a day witho...

The cold temperature during this winter probably resulted in many trunk splitting or scarring on less winter hardy vines.  I am planning to conduct a quick study on the effect of protective paint on the development of crown gall.  If you have vines with split or scars, especially on the young vines (1-2 years on the ground), please let me know.  It will be one-time application, so, it won't take much of your time.

I have a feeling many of you are working on pruning right now to take an advantage of the warm weather.  Please find a handout for the pruning time disease management against many of trunk diseases by clicking this link.

It looks like the winter is finally over.  I hope everybody is ready for the new season. We will start off our season with a vineyard meeting at Cardinal Point Winery at Afton.  The meeting is from 11AM until 3PM or so (note: please bring your lunch).  One of the major focus of the day will be frost protection.  We will also cover seasonal updates as well. Also, I have changed a few things on this blog.  Other than little more modern look to it, the major additions are project pages.  Our lab has several active projects going on right now, and we are finding more about our pathogens that will lead to the development of better management tools.  These page should explain more about our activities.  I will add more pages, but for a starter, I have added trunk disease project page.  As a part of our activities, I have also updated our recommendations for trunk disease management, so,  please take a look.