Skip to main content

Recent disease risk events

Most of VA started a week with a rainy Monday.  At Winchester, the first estimated wetness period started 5 AM Monday morning, lasted until 3 PM (10 hours) with an average temperature of 64F.  The second one started from 6 PM and lasted until today around noon (18 hours) with an average temperature of 64F.  Both were risk events for Phomopsis, black rot, downy mildew, and Botrytis.

Some of you may remember that I was concerning about lack of diseases in our experimental vineyards at the VVA summer technical meeting ;).  Sure enough, I start to noticing a rapid development of powdery mildew on some of border vines, and downy mildew is on its way too!  It reminds me how quickly these pathogens can spread.

Some of early varieties are at bunch closure.  If you have a variety that is susceptible to Botrytis, this would be a good spray timing to deliver a material into the cluster.
Labels:

Comments

Post a Comment

Please leave your comment here. In order to avoid spam messages, l moderate comments, thus it may take a few hours for your comment to be posted on the page.

Popular posts from this blog

Disease risks from yesterday's rain

Winchester area received precipitations from thunderstorms yesterday.  It started around 3:30PM and lasted until 7:00PM.  The actual amount of precipitation was not high (0.05 in) compared with other northern VA regions where a severe thunderstorm warning was issued, but since the ending part of the thunderstorm hit during the evening, the relative humidity was high (>90%) until 2 AM or so.  Thus, it accounted for 11.5 hours of wetness with the average temperature of 73F.  It was warm and long enough for Phomopsis, black rot, and downy mildew. We are still having chances of rain (40-60%) until Monday.
Post a Comment
Read more

Recent downy mildew risk events

 It seems that several rain events have happened over the course of the past two weeks or so. Here is a summary of recent downy mildew risk events, based on the NEWA stations and DMCast. Bristol, VA Fifteen days with potential DM infection event(s) since Sept 1. The latest event happened last Sunday. Floyd, VA Eleven days with potential DM infection event(s) since Sept 1. The last event happened last Friday. Charles City, VA Twelve days with potential DM infection event(s) since Sept 1. The latest event happened yesterday. Central VA Since there was a wide variation among stations, I am listing several around Central VA. Tyro, VA Nine days with potential DM infection event(s) since Sept 1. The latest event happened yesterday. Red Hill and Crozet, VA Only one day with potential DM infection event(s) since Sept 1. Olympic Lake Thirteen days with potential DM infection event(s) since Sept 1. The latest event happened last Sunday. Washington, VA Eight days with potential DM infection e...
Post a Comment
Read more

EPA is reviewing captan

Captan, which we use extensively to manage downy mildew, Phomopsis, ripe rot, and other grape diseases, is currently under review by the EPA. In order to keep captan as one of our tools to control grape diseases,  please respond to the EPA's registration review page to post your comment  (will open the EPA page). With increasing cases of fungicide resistance with newer products in our region, it is very important for the majority of commercial grape growers located east of the Rockies to keep older multi-site materials such as captan to be used as a backbone of the spray program.  Also, please forward the message to other producers and stakeholders who should respond to the need for this fungicide in our industry. 
Post a Comment
Read more