Grape leaves are very artistic and beautiful.Grape are a crop that needs to be tied up to keep it from spreading all over the garden. These are some Chardonnay grapes from last year, and no we don’t use them to make wine. We just make our own grape juice and jelly. I don’t actually tie the vies up with string, instead, I very carefully bend and braid them around and along their log supports or rails. It is a gradual process and involves some patience and persistence.
We have a great book that shows us how to trim everything for fruit. “All About Growing Fruits & Berries”, by Ortho Books. Here is the method I started doing last year and this year and they are beginning to really improve.
The vines are looking very happy this year and are growing quickly. However, I did notice some weird bumps on one of our grape plants while training its vines around their supports this year.
On the top of the leaf, weird raised blisters show up that resembles the kind you get on your hands when you forget to use gloves. 
But, on the back was a white powdery substance so, of course, I had to Google it. Oregon University has some answers from their master gardeners below.
Blister mites are running wild this season. It seems that the perfect conditions combined for population explosions of these tiny, elongated mites which noticeably disfigure the leaves of grapes, pears, walnuts, and more.
Bet you didn’t know that, but now you do.