Stupid tomatoes.
If someone tells you tomatoes are easy to grow. Ignore them. They don’t know what they’re talking about. Then again, maybe they do. Maybe they’re tomato jedi. In that case, listen carefully to their sage advice and then send them this way.
As you can see, some random fungus or another has struck. The cold spring evenings and the torrential May and June rains that Philly suffered didn’t help. Fusarium or verticillium? Who knows and who cares — the result is the same: sad, sad tomato plants with a low yield. At this point, all that can be done (snipping affected leaves mercilessly) has been done.
A glutton for punishment? But of course. Here are a few notes for next year (additional suggestions most welcomed):
- Shop for disease-resistant varieties — don’t be suckered by heirlooms, as much as you love them.
- Start the seeds in mid March, using new sterile soil — no earlier!
- Wash and sterilize containers, purchase new drainage materials.
- Carefully harden off — no cheating!
- Plant early to mid-May (strip off the leaves that are submerged in the soil) — no earlier!
- Spray regularly with Neem and feed them.
- Continue to mulch, water in the morning, and do the anti-fungus-some-rain-but-not-too-much-warm-but-not-hot-weather dance.
Plants On Deck 
Thanks for your comment and sympathy ! I have given it a trim. I don’t mind losing one. My real worry is the risk to the other tomato plants. Is this contagious ? Should I keep it a safe distance away or simply chuck it altogether ?
It’s a little hard to tell from your photo, but I think you grow your tomatoes in containers, too. So, if you’re like me, each plant is precious — however, many tomato diseases are actually fungal, which means they’ll eventually produce spores and spread like crazy. (You may be hearing about the late blight that’s tearing through the Eastern states.) So yeah, if you can bear it, pitch the plant, sterilize the container, buy new soil, and start something new. I couldn’t pitch mine just yet because they’d started producing and I wanted to enjoy whatever yield I could. I’m not terribly worried about the late blight as I started mine from seed (and it’s not a seed borne disease). Good luck.
I’ve found that cutting off any branches withing 10 inches of the soil line and being really vigilant about cutting off all suckers has helped avoid diseases. Also, I prefer to stake my tomatoes rather than using cages because I think it helps keeps air flow moving better.