I've had those on my blueberries before, now that I think of it. Just a few, here and there, so I didn't think much of it. Hmm, this year, I'm spraying ALL my fruit trees with the 10% milk solution (Oh, alright 1:10 milk and water solution - I kinda like the sound of "10% milk solution" -- anybody else like Sir Arthur Conan Doyle's Sherlock Holmes?). Didn't think to specifically spray blueberries, though no doubt some are getting on them as well since they're located between the apple tree and the plum tree. I think I'll start, and I happen to have a 1wk-past-expiration carton of milk in the fridge right now.
... and yes, HG, I'll add the fish hydrolysate when I get-a-hold of some