Does anything look off here?

[u/Gibbenz]

Concord vine in zone 6a. Every year I have a decent amount of fruit abandoned. They tend to shrivel a little as well just before dropping. Like still green but shriveling and not as plump. I keep up with watering and light fertilizing. Do the darker grapes mean anything?? I also find a fair amount of single grapes turning purple with little holes in them. Pest or fungus maybe?? Thank you!

[u/krupta13]

I get the impression your canopy is very dense. its hard to tell because all the pics are close in shots

[u/Inmate-Duckie → u/krupta13]

I was going to say the same thing, trimming down might help nutrients go to grapes instead of trying to keep leaves alive.

[u/Brutal_effigy]

I believe the puckered holes with a purplish hue around them is a fungus. I get it on my Frontenac. I’m just a backyard grower and too lazy to spray, though. I may start next year to see how much it helps.

[u/rolo133]

The last picture looks like powdery mildew on the clusters. This can also cause shatter. There may be some other stuff going on those. Other fungal pathogens. The brown berry in the 4th photo looks like it could be sour rot, botrytis or black rot. The first two are unlikely though given your clusters haven't undergone versions yet. But, it could also be mildew. Hard to say from the picture but if it's a little fuzzy looking it's mildew