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.)
At Winchester, we had light rain events during the night of 6/12/09, but it was short events and the relative humidity was low (80% or so), thus it probably did not promote any infections. However, we are experiencing continuing favorable nights for downy mildew sporulation (average T>55F, high RH (80-100%)) for 10 days now. Yesterday, we conducted a formal disease assessment, and observed first incidence of powdery mildew for this season. We had plenty of infection events in last two months, so it was not surprising. At this point, it is a trace level of infection on untreated vines. Downy mildew was the major disease so far. We had up to 40% incidence on untreated vines. Next runner-up was black rot. It varies vine to vine, but some of vine had 10-15% incidence. Phomopsis was omnipresent as I expected from early May rain falls, but severity was low overall. We will examine diseases again in the near future, and I will update as the season goes. Here is downy mildew ga...
This comment has nothing to do with Topsin-M, however; I was curious if VA growers should be concerned at this point about Red Blotch associated Virus (RBaV). I was purchasing vines from California and there is now a Disclosure Statement you need to sign stating that plant materials may be infected. This seems to be a common request for Novavines, Sunridge, and Vintage before purchase. Has this been seen in VA?
ReplyDeleteRed Blotch associated Virus has been confirmed in a few vineyards in VA. It has been discussed quite a bit due to media hype. Do we have to be concerned? Yes and no. We need a little more research, but my feeling is that the virus has been in VA for a while, but now it got attention probably because we have cleaner vines thanks to efforts of the FPS. In addition, like many other virus diseases, the symptom expression is not consistent. The fruits of infected vines can may suffer lower Brix and higher TA, but as with the cases with grapevine leafroll associated viruses, the actual damage may or may not happen with your vines. It is on my lab's "watch list", but it is not the only one. (It will be a long comment, so, I will come up with a posting in a near future.)
ReplyDeleteThank you Dr. Nita for keeping this blog updated with very useful information.
DeleteBrad