As I mentioned several times, we have an experimental plot where some of vines are not treated with any fungicides. On these vines, black rot, powdery mildew, and downy mildew become very severe. Last time I showed black rot, so, now it's a turn of powdery mildew.
Powdery mildew on upper leaf surface
Powdery mildew on bunches... No, it's not truffle...
Powdery mildew on a cane