Virginia Grape Disease Updates

Well, it looks like we will see more rains coming in next week or so. Sounds like a typical start of the season for VA vineyards, doesn't it? Since most of vines have 2-10 inches of shoots, our main focus will still be Phomopsis , especially if your vineyard(s) experienced Phomopsis in the past.  At Winchester, we are experiencing 27+ hours of wetness with the average temperature of 48F or so. This will be a low Phomopsis risk event, and counting. Plus, especially if you had a serious downy mildew issue in the past season, it may not be a bad idea to think about downy mildew because the next series of rains for this weekend and early next week may happen when air temperatures will be in 60's and 70's.  As for Phomopsis, a protective spray of mancozeb, captan, etc. is pretty much the only mean of management, but we do have some options for downy after the rain event. So, if you did not spray before this series of rains, but you are lucky enough to have a window for a s...

Several growers contacted me recently to discuss about disease management after recent frost events. Here are my take on it. 1) If you have some damages on your shoots/buds. As usual, you work with the growth of the vine, but not with the calendar dates. If you have lost a lots of growth from the primary buds, you may have to start over your spray program.  If you have mixed growth from the primary and secondary buds, you may need to adjust your spray program based on what may come from the secondary buds, especially around bloom. Flowers from the secondary buds may lag behind, thus, you may need protect flowers for a longer period of time. 2) If you have extensive damages on your shoots/buds to the point that you may not able to expect crops. Based on what I heard, we are not seen this scenario this year. However, if you happened to have the major issue from the frost events, well, first of all, I am sorry.  Second, you still need to have some level of disease managemen...

As with many other places in the VA, we were suffering from frost damages.  We experienced several near freezing events this year, and most notably, a few hours of 25F on Thursday morning. Our younger Chardonnay planting (4th leaf) had a bud break around 4/1, and being suffered more from it.  I estimated about 80-90% of emerged shoots are now gone. Our older Chardonnay (8th leaf) is about a week behind, and my visual estimate as of yesterday was about 25% loss.  Some buds/shoots look like they are surviving, but I am not sure how it will go after tomorrow morning... There is a very nice blog post about spring frost from Dr. Michela Centinari at PSU.  If you are interested in, please follow this link. The other items I noticed in our vineyards is damage from climbing cut worm. For us, it always starts from the Eastern side of our vineyard which is facing a small patch of wood.  If it is a warm weather, I would spray for it, but I think I will wait ...

Our 7-yr old Chardonnay vines are in bud swell stage, and others are tagging along.  It looks like we will see bud break in a week or two. One of diseases you need to consider this time of the year is Phomopsis cane and leaf spot .  It causes minor leaf spots, but more importantly, it can cause necrotic lesion on shoots and rachis.  It also causes berry infection; however, it is not common with wine grapes because of our spray programs.  Materials for black rot and downy mildew are often effective against Phomopsis, thus, the coverage for these diseases are also working as management of Phomopsis, especially later in the spring/summer. Phomopsis takes a while to establish in the vineyard; however, once it is established, it is difficult to get rid of this disease.  Some varieties, such as Viognier and Seyval blanc, are more susceptible to Phomopsis than others.  Phomopsis tends to become noticeable as a vineyard gets older becaus...