It seemed to appear overnight.
I've never seen it in my garden before.
Look at my poor onions.
Don't see it?
How about this one.
Downy Mildew seems to be the likely culprit. Lots of rain and mild temperatures seem to be helping it along. A good hot dry spell might knock it back.
In the meantime I gave all of the alliums a good spray of Serenade fungicide.
I sure hope the onions aren't doomed.