Sunday, August 14, 2011

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.

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