Q.grape vine problem
My grape vine is 5 years old and it has produced fine bunches. However, last year and more so this year after the bunches have formed and the grapes are reaching full size, many start to turn a pale brown and start to shrivel, eventually falling. The vine is in a greenhouse with the root outside. To assist, can I send a photo to show this problem?
This may be a fungus issue.
I would treat the grapevine with Neem OIl.
I have listed a few links for you.
https://www.gardeningknowhow.com/edible/fruits/grapes/treating-grapevine-problems.htm
https://www.gardeningknowhow.com/edible/fruits/grapes/black-rot-grape-treatment.htm