Dormant buds can be infected and survive over winter. When these buds shoot they are deformed and covered with the powdery mildew spores. These shoots need to be removed and destroyed. We have come across several shoots this year but hopefully it isn't widespread.
Sulphur and Copper are traditionally used to control mildews on the vineyard. We are trying to avoid these treatments by using compost teas which populate the vines with friendly bacteria and fungi.