sour grapes

I usually have to compete with the racoons to get my fill of the great crop of grapes snaking up the side of the house.  But not this year.  Only one cluster of nice grapes appeared.

The rest look like this:

and like this:

I found some info on
Anthracnose on grapes but no advice on how to avoid it or prevent it from happening again next year.  I think I will just snip off all the affected blighted clusters and get rid of them. 
One source says this:   For organic growers, sulfur and Serenade (+ spreader-sticker) are moderately effective options. Start sprays when shoots are 1 to 3 inches long to protect shoots and leaves and before bloom to protect fruit.

I will try that next year.