Monday, August 27, 2012

Disease risks from yesterday/today

There were two wetness hours recorded yesterday through today.  One happened around 6AM with 6 hours of estimated wetness with 66F, and the other happened around 5PM with 22 hours of estimated wetness with 69F.  Thus, we had infection events for downy mildew and Botrytis.

Once again, our recent conditions (warm and humid nights) are favoring downy mildew pathogens to produce spores.  Please keep eye on younger leaves (upper part of the canopy) to catch their early development.  Severe downy mildew infection can cause defoliation, and you do not want to that to happen at this time of the season.

Also, these extensive humid conditions also call for Botrytis and other late season rots.  Canopy management to promote air circulation and bird management can be a very useful tool to deal with late season rots.  That also reminds me to mention about Spotted wing Drosophila (SWD).  We do have some isolated cases of SWD in VA vineyards this year.  Please keep eye on this newly introduced fruit fly.  If you have a concern on SWD, please contact Dr. Doug Pfeiffer (dgpfeiff@vt.edu).

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