Virginia Grape Disease Updates

It looks like there were some errors with my previous posting, so, here you go again! 2015 Virginia Cooperative Extension pruning workshops Specialists with Virginia Tech’s AHS Jr. AREC and local Virginia Cooperative Extension agents will conduct two commercial viticulture pruning workshops in January. These workshops will involve classroom style presentations followed by guided practice in the vineyard. Both programs will provide a review of the fundamentals of dormant pruning. Moving to the vineyard we will then focus on pruning strategies for vines with winter injury and crown gall where trunk-renewal and retraining are necessary to compensate for injury sustained in the 2013/2014 winter. There will be two meetings! Meeting #1 When : January 19 th 2015 (Central Virginia) @11:30am Where : Democracy Vineyards http://democracyvineyards.com/ 585 Mountain Cove Rd., Lovingston VA 22949 Meeting #2 When : January 23 rd 2015 (Northern Virginia) @ 11:30 am Wh...

Happy New Year to everybody!  Here comes a series of meetings offered through our group.  Hope to see you soon!!   2014 Virginia Cooperative Extension pruning workshops Specialists with Virginia Tech’s AHS Jr. AREC and local Virginia Cooperative Extension agents will conduct two commercial viticulture pruning workshops in January. These workshops will involve classroom style presentations followed by guided practice in the vineyard. Both programs will provide a review of the fundamentals of dormant pruning. Moving to the vineyard we will then focus on pruning strategies for vines with winter injury and crown gall where trunk-renewal and retraining are necessary to compensate for injury sustained in the 2013/2014 winter. When : January 19 th 2015 (Central Virginia) @11:30am Where : Democracy Vineyards http://democracyvineyards.com/ 585 Mountain Cove Rd., Lovingston VA 22949 When : January 23 rd 2015 (Northern Virginia) @ 11:30 am Where : Desert Rose Ranch and...

If you are interested in starting a new vineyard, or just have started, please join our beginner's workshop. Introduction to mid-Atlantic wine grape production  Virginia Tech’s AHS Jr. AREC Winchester, VA (Frederick County) Team-taught program designed for those either exploring grape production or recently engaged in wine grape production. On-site registration will occur from 8:00 to 8:30 am. Program 8:30 am: Introduction and market opportunities: Tony Wolf, Virginia Tech 9:00 am: Vineyard business planning considerations and Vineyard Calculator – predicted cash flows : Tremain Hatch, Virginia Tech 10:15 am: Lender’s perspective on vineyard enterprises : Marilyn Adams, Farm Credit of the Virginias 10:45 am: Vineyard site evaluation and environmental challenges : Mark Sutphin, VCE 11:30 am: Mapping soil variation and geomorphology to improve vineyard design an...

I had a meeting and did not able to post it in timely manner, but there was a wet event on Monday-Tuesday this week.  It was 14+ hours of wetness and average was around 60F.  It was a risk event for downy mildew, and very low risk for Botrytis. Other than a slight chance of rain tomorrow, it looks like we will have a nice cool week!  For the late season spray recommendations, please refer to previous posts. http://grapepathology.blogspot.com/2014/08/note-on-sour-rot.html http://grapepathology.blogspot.com/2014/08/last-stretch-spray-consideration.html

A line of rain went through Winchester area resulted in 10 h of wetness with an average of 69F.  It was downy and low Botrytis risk event.  Please refer to the comments on previous posts on late season disease management. FYI: Our Chardonnay berries are hitting 20-21 Brix and pH is getting near 3.0.  We will see what the forecasted thunderstorms towards the end of this week will do for it...

As the harvest approaches (plus recent rain events in some part of VA), I am receiving several emails on sour rot.  It is often confused, but not all late season rots are sour rot.  Sour rot is basically a disease caused by bacteria that form acetic acid, such as Acetobactor and Gluconobactor .  It is often associated with wounds (birds, insects, hail, too much rain, early season powdery mildew, certain very fair-skin varieties, etc), high Brix level (13-15 or higher), warm temperature range (high 60F to mid 70F). Since these bacteria cannot penetrate berry skin tissues by themselves, what we typically recommend is wound management (e.g., bird netting, grape berry moth management, etc.), and many people mention that it works.  However, with a potential role of Spotted Wing Drosophila (or lesser extent, African fig fly), which may able to penetrate skin, there is a possibility that we may see more sour rot in the future.  Luckily, Dr. Wayne Wilcox's group a...

Due to the rain event over the weekend, many people are concerned about protection for next week or two before the harvest.  At this point, the tools are rather limited due to PHI as well as wine making consideration. For downy mildew (especially for foliage, your berries are protected at this point), you can use Phosphonate (= phosphorous acid) product or captan.  (Both have 0-day PHI) For late season rots, especially Botrytis, you can use captan, Elevate (both have 0-day PHI), Switch (7-day PHI), Rovral (7-day PHI), Scala (7-day PHI), Vanguard (7-day PHI), or maybe Endura, Pristine or Luna products (these three have 14-day PHI). For ripe rot and bitter rot, a QoI (Abound, Pristine, Sovran, Flint, etc = 14-day PHI) and captan seem to be the key product.  Our lab is investigating the efficacy of a phosphonate too. As usual, please consider the situation at your vineyard as well as weather forecast.  If you do not see any issues at your place, picking in 7-day...