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. 

Rescheduled Vineyard IPM Meeting Meets this Friday Date:           Friday, March 21, 2014 Time:          10:00 a.m. to 4:00 p.m. Location:   The Nelson Center, 8445 Thomas Nelson Highway, Lovingston, VA Contact:     Michael Lachance, Nelson County Extension Unit;  (434) 263-4035 The central Virginia vineyard IPM meeting, originally scheduled earlier this month will be meeting this Friday, March 21 st in Lovingston, Virginia,  located roughly 30 miles south of Charlottesville & 35 miles north of Lynchburg on Highway #29. Dr. Mizuho Nita and Tremain Hatch will conduct this informative, pre-season briefing on how to manage the challenges of the 2014 growing season.  In addition, Dr. Jeff Derr will contribute recommendations for vineyard weed control.  This will be an excellent opportunity to review our past challenges to quality...

If you are pruning, and wondering whether you can protect pruning wounds from infections by trunk diseases, t here is a supplemental label of Rally for control of various trunk diseases (Botryosphaeria, ESCA, and Eutypa).  Also we have a special use label of Topsin-M for VA.   You can apply them with a sprayer or as a paint.  It would be a very good idea to use them, especially when you are making a big cut.  The timing of application would be soon after pruning and before a rain. Also, double pruning (early winter rough cut followed by the final cut in early spring) showed to reduce 95% of trunk disease in a CA study.