Tuesday, September 10, 2013

Night time dew events

Since 9/2 or so, we are observing dew events that were wet enough to make our leaf wetness sensor wet almost every night.  Since our sensors were located about the same height as the lower part of the canopy, leaves were probably wet as well.  Each events were about 6-9 hours.  Most of time, temperature was low (in 50F), but sometimes were in lower 60F. 

What this condition promote can be downy mildew.  They tend to sporulate under dark condition, and since their spores can swim, these dews probably are enough for them to infect new tissues.  Due to low Brix, many people are tying to hang their berries longer this year.  Please make sure to have some protection on your foliage so that it can help maturation of berries (+ store carbohydrate for the winter!).  If you are concerned about potential effect of spray materials on wine quality, you can aim your sprayer nozzles to upper part of the canopy so that fungicides won't hit the berries.