Those blisters on the foliage look like rust disease, a fungal infection encouraged by cool, moist weather. Pick off infected foliage to stop the spread and prune to increase air circulation. A fresh mulch on top of the soil could help to seal in the spores that have fallen to the ground. Grapes can be sprayed with a copper based fungicide following the instructions on the label.  A change to dry weather will help as well. Keep growing, Marianne Binetti