I got the same thing on "Patio Tomatoes". I always thought it was some sort of blight. Never killed my tomato plants either, just made them unsightly.

I'm having very similar issues with mine, but mine have not produced any fruit yet. My bottom branches turn bright yellow, then curl up brown at the leaves. Then the whole branch falls off. I do have a few cherry and grape tomatoes, but those plants don't have it as b ad as some others.

I hope someone answers this question.

archerb - these are season old plants, correct? If so then it is normal for plants to begin dying back from the bottom up as the season ends and from what I can see, this is all old growth.

However some of the leaves I can see also look like powdery mildew - the yellow and green spotted ones - and if you have quite a bit of the growing season left you may want to invest in one of the fungicide sprays.

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On the other hand, yellowing of leaves in new young plants (haven't produced yet) almost always is a sign of too much water. The leaf then dies and falls off.

The link below is a good one to bookmark when it comes to identifying tomato problems.

Dave

Here is a link that might be useful: TAMU - Tomato Disorders

I cant say for sure BUT, I had unsightly plants like yours too, that were not diseased. Stems were turning copper brown color from the bottom up and would turn leaves yellow and brown. In my case it was russet mites, they are very small and hard to detect with the human eye. These little suckers remove cell contents from the plant which destroys the plant. Check out this link or search "russet mites".

Damon

http://www.ipm.ucdavis.edu/PMG/r783400111.html

Re: Digdirt.
One of these plants is old. It was planted back in July. The other is just a couple of months old, however and is just now starting to produce fruit. I don't know if they'll have time to mature before frost does it in. Also, the older plant has had this problem all summer. This being my first year, I didn't know if it were normal or not since production was well beyond what I should have gotten with the temps we had.
Also, I thought I may have powdery mildew at one point, but had ruled it out for reasons that has been purged from the memory banks long ago. I think sprtsguy76 nailed it.

Sprtsguy76:
I think that's it. I googled russet mites and found a thousand pictures of the little buggers under a microscope as if that were going to do me some good. Finally, I found one that actually showed accurate symptoms. That one was the very last picture on this page:
http://www.hydro-gardens.com/mite_damage.htm

Thanx Damon. Now I have to decide if it's worth it to pay for treatment with only a month or two left before frost kills the plants off anyway and the birds eat the rest of the fruit!

Thanx to everyone who helped out.