What are the white fuzzy things that appear on your grape berries after present?

Powdery mildew and botrytis are two fungus diseases that frequently afflict grapes and appear as a fuzzy-white coating. Although powdery mildew causes white, powdery specks or patches on young shoots, leaves, and grape berries, botrytis, usually known as "noble rot," produces a cottony gray and eventually brown fungal growth.