Botrytis on Bunch Grape
For those of you growing bunch grapes we have the following alert from our bunch grape specialist; Sara Spayd:
Although NC conditions do not always support Botrytis (generally too hot), with the rainy, relatively cool weather we are having, Botrytis has reared its ugly head in bunch grapes.
The high rainfall and relatively good fruit set conditions this spring are leading to very tight clusters. Berries are likely to be squeezed off clusters providing a supply of nutrients for Botrytis and other fruit rot organisms. Given the persistent rain conditions and that bunch closure has occurred, we have a very high potential for rapid spread as long as conditions remain warm and humid. Gorwers should check the chemistries that they have already used for Botrytis control and DO NOT USE additional fungicides of the same mode of action as those already used. CHECK THE LABELS.
Fruit ripening is still behind though berry size can be expected to expand rapidly once the fruit hits stage 3 of growth (engustment) when water starts to fill in the berries..