Posted: 12/04/2015 at 11:58
Peas are prone to mildew unfortunately. You can try varieties that claim to be resistant. Doesn't mean they won't get it but (it is claimed) they will cope better if they do get it. It's also a good idea not to plant too close together. Allow plenty of room for air circulation.
I found fewer problems by planting as early as possible. Peas are incredibly sturdy, seedlings especially, and will cope with low temperatures. I've seen less mildew with a bit of chill in the air.