debor039

First of all, Happy New Year! I hope you had a nice holiday season. Here's a table of upcoming vineyard meetings. 2017 Upcoming Virginia Vineyard Extension Meetings Program name Location Meeting details and registration information 24-Jan Pruning Workshop Honah Lee Vineyard, Central Virginia https://goo.gl/forms/J48R5RKwlFg76ckw2 23-Feb New Grower Workshop Charlottesville http://www.virginiavineyardsassociation.com/2016/12/winter-technical-meeting-registration-opens/ 24-Feb VVA Winter Technical Meeting Charlottesville http://www.virginiavineyardsassociation.com/2016/12/winter-technical-meeting-registration-opens/ 7-Mar Pruning workshop Breaux Vineyards, Northern Virginia More information coming soon 16-Mar IPM meeting – Pre-season training for vineyard pest management Early Mountain Vineyards, Central Virginia More information coming soon 9-Mar...

It has been pretty wet week so far. At Winchester, we observed about 11 hours of wetness on the 26th with an average temperature of 64F, 50+ hours (and counting) from the 28th to today with an average temperature of 61F. It is certainly long and warm enough for Botrytis infection. Whether we require a fungicide application for Botrytis or not at this point depends on several potential factors. The first one, of course, is whether you had a previous application or not. If you had a previous application to cover these rain events, you probably do not need to be concerned much. The second one is a time to harvest. If you still have several weeks to go, you may want to consider an application, but if you will harvest within a few days, I am not sure an application of fungicide will help you much since we do not have any curative materials for Botrytis. Whatever we spray at this point will be good against future infections, but not the infection happened already. The third is cultivar. Chan...

Maybe I should keep posting that rains are coming... Each time I do, it looks like rains disappear. ;) If you have not subscribed to the email list of Dr. Tony Wolf, who is our viticulturist, please do. It always have a wealth of information. In his latest newsletter, he explores potential reasons why some of cultivars are stalling on ripening process this year. Our Chardonnay is still stuck at 19 Brix or so too! The below is a link to his newsletter, but it typically take several days for the newest one to appear. Thus, the best way is to subscribe to his email list (the instruction for subscription is listed on the page too). http://www.arec.vaes.vt.edu/alson-h-smith/grapes/viticulture/extension/VN_options_index.html

Well, I was hoping that the rest of the season would be nice and sunny, but I was little naive. Looks like some portion of VA may be affected by tropical storm Hermine. Plus, probably due to the hot several weeks with no cooling time during the night in August, some cultivars have been very slow to ripen. I was bit surprised to see our Chardonnay is still around 17 Brix this week. Thus, I complied a list of fungicides with relatively low PHI (7 days or less). I cannot cover every single fungicides out there, but I tried to cover common ones. Please click here to download the table from Google drive. NOAA's precipitation prediction for Harmine as of 2 Sept. 2016

I heard that some of early cultivars are ready to be picked on 7-10 days.  Looks like no tropical storms to worry, yet... (crossing my fingers!) There have been frequent thunderstorms went through our area, and some of them (like the one we had last night) resulted in a significantly long wetness event (8 hours). These wetness events, especially the one happens overnight, are preferred by downy mildew pathogen since they produce spores in dark, moist conditions. Please check my previous post on late season downy mildew . As usual, protection is the best approach.  If you have seen some downy mildew on foliage, it would be best if you can mix a protective material (e.g., copper, captan) with a phosphonate (Prophyt, Phostrol, etc). If there is heavy downy mildew already happening, please do not use Ridomil (metaxel) products because they are known to be overcame by the downy mildew pathogen. Some of reds are probably going through veraison, which would be a good timing for your ...

As many other parts of VA, we have been experiencing thunderstorms running through our area in the past week for so. Yesterday, we had about 9 hours of wetness with an average temperature of low 70's, then followed by a very humid night with an average temperature of mid-60's. These conditions are conducive for downy mildew development. Please check the previous posting for more information on downy mildew management. Also, as veraison approaches near (or happening for some cultivars), please check 12 July posting on late season disease management.

At Winchester, we had 8 hours of wetness observed on last Thursday, then there are several short rains/thunderstorms. Moreover, the night time relative humidity has been fairly high (> 95%) in the past few days. These conditions favors downy mildew development because downy mildew pathogen prefer 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 see infection on the top of the canopy around this time of the year because younger leaves are more susceptible than older ones. Once infection gets severe, it can defoliate infected leaves. As usual, it is much better and easier to have a preventative program than try to play a catch up game. There are many good protective materials for downy mildew, such as Revus products, Zampro, Forum (Please note that these three share the same mode of action), and Ranman. In our small trial, we found that fixed copp...