These are Niagara grapes, the type used for making white grape juice. Notice the shriveled black grapes. This is black rot. The last 2 years I lost almost all of my grapes to this fungus disease. The unaffected grapes can be eaten, but the clump looks bad. If I can increase the brix level of the young green grapes and leaves to 5% or above, I am told that black rot will not flourish. I recently met a Sardinian wine grape grower. He told me to extend the arms on the trellis to 3 and a half feet, instead of 2 feet. This will allow room to pull the leaves off above the grape clusters, yet room enough to run the vines back and forth along the wire on the ends. Exposing the grape clusters to sunlight causes the brix level to increase, making sweeter, more nutrious grapes with hopefully, more black rot resistance. These grapes are testing 17-20 brix. They taste sweet and good and I am soon going to make grape juice.