What is wrong with my grape vine

Question

every year for the past several years my grape vine has made grapes, but then they rot and fall off before they even get ripe. What is wrong with it?

Answer 1

I'm not sure if this is the correct answer, but I found the following:

Mildew, rot and other fungi are easily dealt with by growers, except under extremely wet weather conditions, with the help of fungicide and severe thinning of diseased fruit. Still, consumers may come across the occasional wine that has off-flavors and moldy aromas. But rot isn't always a bad thing, particularly if it's Botrytis cinerea, the so-called noble rot, which help make Château d'Yquem and other famous dessert wines possible. It attacks grapes under certain climatic conditions and causes them to shrivel, deeply concentrating the flavors, sugar and acid.