So I asked perplexity.ai - diseases or conditions that cause white or light colored spots on the foliage of garden vegetables including brassica greens, cucurbits and melons but not tomatoes or peppers.
One or more of 11,000 different types of Powdery mildew was #1 and most common. I have no purple so it's not downy mildew and all else were obscure conditions.
My maters and peppers are unaffected. The #1 cure is to plant resistant varieties and by my reading, I'm kinda stuck with it now that it's here. Pull all affected plants and trash or burn them. That would be everything but the tomatoes and peppers. Treat as soon as you see -- too late
And now I feel like pulling all my mulch out so things can dry up and also wondering if I didn't bring it in with the hay I'm mulching with. I just started mulching but the hay has been sitting in the tunnel for a few months now and I've never had an issue with any sort of foliage condition until now.
I can see why some people don't bring in "resources" from outside. I brought horse nestle here with a load of horse manure and now possibly downy mildew with some hay.
Resistant Varieties rules out Baker Creek for seeds since they don't rank anything by resistance to common issues. Just did a search on rareseeds.com for "powdery" and got a whopping 12 results including 6 squashes and 2 flowers.
Well this sucks.
I’m sure you’re getting it in spades this season with all of the WET.
When I have it (usually on Zucchini plants in a wet season) I use Copper Spray and that works like a charm. Zinnia seem to get it too, and a blast of copper usually helps them, though they make so many mildew-resistant varieties now that it’s not usually a problem.
I wouldn’t beat yourself up about the straw; it’s more of a moisture thing with MORE than perfect conditions for All The Mildews this season. :(