Skip to main content

Rain, rain, rain...

I finally came back from two-week trips to a series of conferences.  It's nice to be back, and see some rain!  (Winchester area has been very dry when I took off. I will check what happened in the last 2 weeks after posting this note, and add entries if needed.)  However, at this point (sugar level more than 8%), the type of rain we are experiencing (providing a long humid condition and in mid-60's to 70's) is favored by Botrytis.  I believe some of you have already prepared for this rain and protected your berries with a Botrytis material (Flint, Pristine, Rovral, Vangard, Scala, Switch, etc).  If you have not, many of Botrytis materials do not have a real curative activity to speak of; however, they do have a little efficacy after infection.  Thus, it is probably better to cover your berries than do nothing.  You can use any of materials listed in the PMG or my spray guide; however, please rotate mode of action!  Botrytis is known to develop resistance to chemicals rapidly.

Other disease to be concerned is downy mildew.  At this time of the season, we are aiming to protect leaves.  If you have seen a sign of downy mildew on younger leaves (older leaves are more resistant against infection), you may want to consider using a downy mildew material.  If you decided to do so, be aware of PHI.
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