Thanks so much for the info. Sorry it took me a few days to reply, my work schedule has been a little insane... I had thought leaf spot was possible, but the beginning stage of this fungus was like nothing I could find (picture or description) describing Septoria. It looked like a black/brown dust (raised) was covering the undersides of the leaves- like someone held the plant upside-down and spilled soil on it :) If two of you think that's what it is, then it must be. I thought rust both because that was the ONLY fungus that looked even remotely similar and we had rust on a jasmine vine planted about 6 feet away in the flower bed (this tomato is potted so it does not share soil with any plants). The good news is- after an all out assault of (Safer) fungicide (every 4 days) and seaweed- the plant appears to be in recovery. A couple of the young tomatoes appear to be a bit deformed so I'm going to keep a close eye on it. The leaf loss was quite extensive, so I may have a problem with sun scald. (btw, in a couple of the photos you can see the whole plant behind me- it's the potted plant on the white stand). QUESTIONs: If I start using Fish Emulsion with the seaweed now will it encourage some more leaf production to help the sun scald problem? Or will any new leaf growth be effected by the fungus? The plant is potted so I have not grown anything in the soil before, it must have picked up the disease at the nursery. This is my ONLY potted tomato and I'm noticing a few spots on my other tomatoes (planted in a garden), if I catch this fungus early enough will it contaminate the soil? Sorry if it was unclear, all of my plants are outside (I brought my laptop out and used the camera built into it to take the pics- GO MAC!!!) Thanks again for all the posts, diagnosing this little fungus had truly been driving me crazy!

Here's a pic of the creatures underside.

wulfe, There are quite a few Class 1000 Cleanrooms available down here in Silicon Valley right now. I am thinking about it..... Raybo

If you don't remove the infected foliage from the plant and dispose of it away from the garden the fungus just continues to spread even with fungicide treatment. So the first rule of thumb is to never leave damaged foliage such as that on the plant. Then use your fungicide sprays. Dave