Virginia Grape Disease Updates

Boy, it has been a rainy month of September! If you are subscribing to Mark Chien's "Wine Grape Information from Penn State", you probably seen this, but here's a link to NOAA on the precipitation record from Irene and Lee .  It gives you an idea of how we started this month with a lot of moisture in the air.  As you can imagine, this type of weather will increase risks of having late season rots.  I have heard some people had an outbreak of Botrytis, sour rot, ripe rot, etc.  The pictures above are examples of Botrytis bunch rot.  The management strategies for these rots are discussed in the previous post .  Since temperature during these rain events were low and we have not have many days with sunlight, you may want to keep your clusters hanging little longer.   Please keep remind yourself about the PHI when you decide to apply fungicides. One of the strategies for sour rot and Botrytis management discussed was the management of birds....

I thought I would wait until the rain stops to update the blog, but rains are keep coming and even when we do not receive precipitations, the air has been so damp that the relative humidity has been above 90% for a while.  It started late night on 9/4, and still going.  So far, I counted about 90+ hours of estimated leaf wetness. The temperature has been between low 60's to mid 70's.  This has been ideal condition for both Botrytis and downy mildew to develop.  As for downy mildew, your berries should be resistant to infection, thus, concern is on foliage infection.  Vines need healthy leaf areas for accumulation of carbohydrate into main trunk in order to survive the winter.  With a concern on the PHI, one of Phosphorous acid or Phosphonate materials should be a good choice.  They also provide a good kick-back activity too. I have covered Botrytis earlier in this blog, so, please click here and here for more information.  If you decided to ma...