Leaf diagnosis needed

[aclum]

Hi,

I've been following Naysen's thread on his tomato foliage problems with great interest and thought of posting there, but didn't want to confuse things, so thought I'd just ask for help in a separate thread.

I haven't really been able to identify the problem myself as the various photos I've found of the same disease can look very differnt from each other. Anyway, here are a couple of photos of a typical leaf. I'm suspecting powdery mildew or a nutrient deficiency. So far I've just been cutting the leaves off with seemingly no harm done to the plant. The leaves are always towards the bottom of the plants. I have observed some thrips and what I'm guessing are red aphids, but they haven't been widespread.

Thanks!
Anne