Why are my grapes turning grey and splitting

Question

I am contacting you in hopes of identifying what is wrong with my very small vineyard grapes. Last year I had a great crop with really no problems. This year I have a problem I hope I can get you input on. I am in Folsom CA and the vines in the attached pictures are Merlot and Cabernet. Most of the grapes have turned grey, as you can see in the picture, and they are not maturing (stunted in size) and many are splitting. I do not see any fuzzy white stuff on the grape leaves, indicating Downey or Powdery mildew. I did have some leaves develop yellow spots and finally the leaves turn all yellow and fall off. Do you have any idea what this could be and how I could treat it? I would really appreciate your input as soon as possible.

Answer 1

These articles should help:

https://www.gardeningknowhow.com/edible/fruits/grapes/treating-grapevine-problems.htm

https://plantdiseasehandbook.tamu.edu/food-crops/fruit-crops/grape/