powdery mildew on Black Hamburgh grapevine in greenhouse

I dont think there is a way of completely getting rid of it! Its down to warm wet weather and only way is good hygiene of burning or binning all leaves when they start to fall. Copper sulphate rings abell but not sure if its organic? More of a prevention ish thatn a cure. Garden centres stock it, but ask about its organic-ness or other products

Thanks Nickyo8
prune

Copper Sulphate is no longer available is there anything else?
prune