Magnification shows absence of critters?

Dan

Dan, I've checked for bugs, but don't find any signs. The underside of the leaves look similar, the lighter areas exhibit some transparency when viewed from below--but that's about all I can see. (That's a 3.5" square pot. The plant's largest leaf is perhaps two inches in greatest diameter. I think its growth is a bit stunted as most of my others are bigger.) I haven't tried magnification, I will try tomorrow. Those critters would have to be truly minute.

I checked the plants for insects, but I don't see any. No aphids or mites. I've seen some similar mottling/spotting--although with small brown holes--on one of my cucumbers, so I'm starting to get concerned it could be the same problem.

Does anyone know what this is--or how I should try to treat it? Would treating it for rust hurt anything if it isn't a fungus? Is there a university website which would help me?

I have the same light-colored spots on geranium leaves brought in from the garden for their third winter. THey are different than all pictures on the web. Only one leaf had miniature aphid or scale like insects. The disease is not on all leaves. A few of the stems are rotten which points to a bacterial infection now perhaps transmitted through the soil. I'll spray with neem oil, but I bet I loose these big healthy hardy gorgeous geraniums.
My light colored spots seem to stay under the surface of the leaves but develop some orange coloring on their edges as the plant matures. But it's not rust or any of the other fungus diseases pictured.
I lost a rare scented geranium that dropped it's leaves and grew in the same pot several months ago. My guess is it's bacterial and I'll have to destroy the plant and throw away the soil. What have you found?

I have the same thing. No one seems to be able to diagnose it. Now the leaves are turning brown and falling off.