Virginia Grape Disease Updates

I was out of town, and I did not realize it, but Winchester area received precipitations from a thunderstorm on the night of the 24th.  Since relative humidity was not high (60-70%), leaves did not stay wet for a long time.  (I could not see any measurable precipitation data from Winchester airport.  Maybe some errors of their instrument?)  Thus, there was no grape disease risk associated with the rain. Looks like we may see some rains next week.  If you have issues with Phomopsis, it may be a good idea to think about protective application of a fungicide such as a mancozeb product. Also, I uploaded an updated version of the workbook since I received some comments, including one from Dr. Anton Baudoin of our department ;) 

Here comes 2013 version of " Workbook for Developing an Effective Fungicide Spray Program for Wine Grapes in Virginia ".   Although I finished it a few weeks ago, and used in the IPM workshop, I forgot to post it in here!  As with the previous version, it may contain some errors, so, if you find any (or if you have comments and suggestions), please let me know. You can also download our Pest Management Guide and other materials, including Excel version of the template from the workbook, from the "Resources" section on the right hand side of this blog.

Both Chardonnay and Merlot are near 100% bud break as of today.  At this point, one disease to be considered is Phomopsis cane and leaf spot.  If you have a history of Phomopsis in your vineyard(s), mancozeb, or captan, or ziram will be a good choice for protection of young tissues. I have not seen much of Phomopsis in our young vineyards, so, I will skip this spray, and start my program around 5-10-inch shoot growth, targeting downy, powdery, and black rot prevention.

The two hot days we had pushed things quickly.  Our Chardonnay buds are swelling and some are even broke.  Our Merlot is bit behind, but not by much.  Cab sauvignon seems to be still tight.  Looks like the season will start very soon!  Since we saw a bit of damages, I applied climbing cutworm treatment to the area of vineyard where we historically have issues.

It looks like things are finally warming up!  We will see how it will go next week. I updated my spray guide for non-bearing grapevines.  This guide also contains basic disease information, so, if you are interested in, please check it out . My workbook for bearing vines will come very soon.  I am hoping to get it published by the end of this week.

A few people asked in about Topsin-M application for pruning wound protection against Bot canker, so, here is my old post about it .  You can also download a special label for the dormant application from the link.  (Please make sure to have it when you decided to apply Topsin-M.  As you know it is a legal requirement.)