Powdery mildew.

Glad to help but you do realize this is a lawn forum...right?

Usually Powdery Mildew forms on the plants leaves, not on the fruit, although a severe case might spread to the fruit. Is this any where else on the plant?

oh, my bad! lol I bounce back and forth between the organic and organic lawn forum.

And, no, I haven't really seen it on the plant. Just the part I was trying, with difficulty, to explain: It's the little things that peel back and reveal the bloom which eventually becomes a tomato. And it's a pretty thick fungus too.

And while we're on the subject, and since fungus is a popular topic on this forum: I have had real problems with fungus this year. And all this despite the lack of rain, drip irrigation i've used for 2 years now, and hard fighting vs. weeds.
Any more preventive measure I can take?