Virginia Grape Disease Updates

Tremain and I will be participating in an upcoming webinar on January 13th, 2021, which is hosted by PSU. It will start at 10 AM, and we are planning a 2-hour meeting to cover pruning related topics. Please join us, if you have time. You need to register to receive an invitation. https://extension.psu.edu/dormant-grapevine-pruning-workshop-and-commercial-grower-panel Also, please take some time to answer our survey on ripe rot!

Dear all,  If you have a moment, please fill in the survey below. A team of researchers, including myself, is working on a new grant proposal to develop management strategies against various fruit rots including grape ripe rot, which is caused by a series of Colletotrichum fungi.  The aim of this survey to determine what we need to focus our research effort. The project aims not only grapes, but other crops, so, please enter your input so that voices from grape growers will be heard. Thank you in advance for your time. It should not take more than 5 min.       https://uky.az1.qualtrics.com/jfe/form/SV_d59ecltm2mqbbw1 Best, Mizuho

 I created a short video describing current projects in my program. 

Hurricane Delta seems to impact our regions, starting Saturday (10/10), and rain may last until Tuesday (10/13) or so . Depends on your location and cultivar selection, you may have some grapes that may need more time before harvest. ( A link to Hurricane Delta tracker from Weather.com - will play a video. ) The target diseases right now are late-season fruit rots (Botrytis, ripe rot, bitter rot, etc.) and downy mildew (on leaves). The links here are  the presentation slides from the last viticulture meeting that covers some of the diseases mentioned above  and   a list of short PHI materials for Botrytis, powdery mildew, and downy mildew , which may help you decide what to do. If you decided to wait until the storm is over, there are several materials with a very short PHI that you may want to consider, such as Oso/Ph-D or Elevate for Botrytis and a phosphorous acid (Prohyt, Phostol, etc.) or Lifeguard for downy mildew. FYI: when we tested in the field, Oso plus Double N...

Looks like a tropical storm Marco is moving westward, but Laura may hit our areas during this weekend. The current forecast shows (opens a new window with a link to Weather.com) potential movement to Virginia and surrounding states around this Saturday (8/29). Many white cultivars will be either ready to pick or getting very close to harvest, and red cultivars may have several weeks to go, depends on where you are what you grow. At this point in the season, the target diseases are late-season fruit rots (Botrytis, ripe rot, bitter rot, etc.) and downy mildew (on leaves). For whites, it may be a decision of when to pick, but not what to spray. If you decided to wait until the storm is over, there are several materials with a very short PHI that you may want to consider, such as Oso/Ph-D or Elevate for Botrytis and a phos acid for downy mildew. FYI: when we tested in the field, Oso plus Double Nickel combination worked well against sour rot. For reds, it will depend on when and what you ...

With recent rain events and warm and humid nights, the risk of downy mildew and Botrytis are probably high in many areas of Virginia. For example, I counted seven days (at Winchester, VA) and eleven days (at Rustburg and Scottsville, VA), with downy mildew infection events in the past two weeks according to the NEWA model ( http://newa.cornell.edu/ ). It is very important to keep your vines protected, and if you think you need to have a kick-back activity against downy mildew to counteract the recent rain event that your previous spray might not have provided good coverage, add a phosphorous acid material such as Prophyt or Phostrol.  Please refer to this list of materials with short PHI since some of the cultivars are getting very close to harvest. Note: although both sulfur and copper have a short PHI, we typically do not recommend spraying these materials within 3-4 weeks of harvest due to its potential negative impacts on the fermentation or wine quality.  When some ...

Thanks for attending today's online Extension meeting. Please find the materials I discussed today below. 1) Presentation slides (will open a new window with a pdf file). 2) List of short PHI materials for Botrytis, powdery mildew, and downy mildew.