Are you sure it's Early Blight or could it be another fungal disease?
Have you checked out the Tomato Problem Solver? If not, just search this forum for it.
I would guess from your location that conditions there would be conducive to several fungi. Don't get discouraged. Daconil and Neem Oil are effective controls for some diseases.
Lets hope Carolyn offers her advice.

It seems more like Verticillium Wilt I guess. Started out w/ misty haze at tips of older leaves, then yellowing, turning brown & drying up--throughout plant.

WHATEVER it was, Blight or Wilt--I'd just like to know *WHY* it attacked a healthy plant, grown under sterile conditions in a hanging basket--with no nearby neighbors' tomato plants in apt. complex to catch a disease from. I need to know WHERE the bug came from, before I ever attempt to grow a cherry tomato (chemical-less) again.

If it was early blight, the spores for that disease are very small and light and can be carried for miles on the wind. You don't need to have an infected plant next door.

As whizzer noted, there are protective sprays that you can use, but they have to be applied before the plant becomes infected. The spray only prevents the germinating spores from penetrating the leaf. It doesn't do much good to apply the spray after the fungus is already growing.

If your plant was infected by a fungus such as verticillium wilt, then I wonder if you started the plant yourself from seed in sterile soil, or acquired it as a seedling from somewhere else. This fungus lives in the soil and attacks the roots, even though the leaves will show the effects. If you got the plant as a seedling, the fungus could have already been in the soil that the seedling was growing in, so planting it into sterile soil in your hanging basket wouldn't make any difference. Another possibility for spreading such a fungus is via your gardening tools. If you used them in infected soil and then used them for planting this tomato, the fungus spores would be transferred into the clean fresh soil on those tools.

If it was verticillium, discard the soil from the hanging basket. (Put it in the trash, don't infect the soil outside your apartment by dumping it there. Verticillium infects other plants too, not just tomatoes.) Then disinfect the pot and all the tools that you used.

Oops, I see now that you said they (3) were planted from a new Perry Morse seed pkt. So they weren't acquired as started plants, bringing infected soil in with them.

But actually the description, "started out w/ misty haze at tips of older leaves", doesn't really sound like either early blight or verticillium wilt.

Did you have all three of these plants in one basket? If so, I wonder now if the plants didn't simply starve from being overcrowded. Did you ever get any tomatoes from them?

Pics of sick (but not dead) leaves, and especially of any discolored spots on them, are very helpful.

Some history: I'd been inspired to try cherry tomatoes in a hanging basket when I saw pots of healthy (& tasty) ones growing at local nursery. Bought all it took there to achieve SAME result (same seeds, soil, planter). Nurseryman even suggested planting 3 in the 12" pot (as they had).

The "white haze" (powdery mildew ?) began same time blossoms began showing. I started picking leaves off, but they won the battle. Yes--I now have a couple dozen little green toms, hardly any green leaves left; yellow & dried-up ones hanging on.

Just had a thought on how to solve this: Am taking a sample branch down to the same nursery that influenced me. Will let you two know what they say. Thanks for your thoughts, I appreciate your concern.
~sootie

Well, saw the nurseryman re it.
Found out WHAT it is--definitely "Powdery Mildew."
Still not positive WHY it attacked tho. He thought they got too much humidity. Maybe, but didn't affect his toms in same zone. And, yes, fungus spores might have flown in from afar, or some other unknown alien source....

He recommended using a sulphur type spray next time (among other chemicals). No 'next time'--I don't think I'll go thru the sad hassle again. Will keep to growing unchallenging, healthy herbs on my balcony, and buy my cherry tomatoes instead.
~sootie

Cherry tomatoes are typically very prolific producers. I had one six feet tall last summer--though our growing season is over in July due to heat and late blight, generally. You don't say what type you planted, but three to a 12 inch pot sounds too crowded. It may be pretty, but good air circulation prevents some types of fungus. Serenade is generally accepted to be organic (though there are some that would argue that). Do clean the pot and any tools because spores live a long time. You might have better luck trying again with one plant and pre-treating--especially if you live in a humid place (I'm on the Gulf Coast so we're used to that, too.) Don't give up!

Actually, I went to my local garden shop to get flowers & a hanging basket. But, while there I saw that they had a couple hanging planters filled w/ delicious cherry tomatoes.

Was told they had 3 plants per 11" basket. So, I bought all to get same results--same potting soil, same size basket, same potting soil, same fertilizer, and the same brand of tomato seeds (Ferry Morse--Supersweet 100 VF Hybrid "Guaranteed to Grow"). I nursed them fine for weeks until a few bunches of tiny green tomatoes started growing....

THEN, the leaves started losing healthy green, drying & dying out--and all that was left were a few bunches of sickly little tomatoes trying to turn red. It was a labor-intensive, expensive, and sad (like losing a kin) experience for this non-farmer. Thanks for your kind pep talk--but I don't have the courage to try it again, figuring invisible spores are still lurking around to get me again. Flowers this season. ;) ~sootie