Q.Why are my grape clusters shriveling and not ripening
I had a lot of green grape clusters on the vine, but they have begun shriveling and not ripening. What have I done wrong?
There are several possible diseases. More information here:
https://www.gardeningknowhow.com/edible/fruits/grapes/black-rot-grape-treatment.htm
https://www.gardeningknowhow.com/edible/fruits/grapes/preventing-pierces-disease.htm
Two diseases found especially in cool, moist weather are botrytis
http://www.ipm.ucdavis.edu/PMG/r302100111.html
and downy mildew https://www.gardeningknowhow.com/plant-problems/disease/downy-mildew.htm
You can take some fruit and leaf samples to the county extension service for a positive identification. This link will help you locate the closest one:
https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm
