anney, Below is the updated link to the aggie problem solver.
Click on Leaf then just match the photos to your leaf.

Here is a link that might be useful: TX Aggie- tomato problem solver

Crush 2 Asprins and Mix 1/4 teaspoon of 20 Mule Team Borax to 1 Gallon of Water and drench soil surrounding plant.

Boron deficiency is very uncommon.

Call your county's Extension Service office to ask if it's a problem in your region.

Beyond that, when I searched for images of boron deficiency on tomatoes *nothing* matches, or even comes close to your image.

Here's a simple way to tell if you have a boron deffincancy. Plant some broccoli in that spot this fall.if you have holes in the middle of any of the plants when you cut the head you don't have enough boron. you could just fertilize with something that has boron in it. However don't over do it to much boron is very hard to correct.

Wow, that is so odd! The discrepancy there is huge. I had the same sort of weird thing happen in my garden last summer-- one plant randomly just turned brown and died. I do think most micro-nutrient deficiencies are imaginary. In the end, I can usually narrow it down to something much more obvious (It got eaten by a bug, I put a plastic bag under the mulch and it didn't get any water all summer, I sprayed it with insecticide meant for humans, it drowned because I didn't put any holes in the container). You may be a less dumb gardener than me, but either way, it seems like stuff like that is so hard to diagnose for sure that you're mostly shooting in the dark. Maybe dig it up and see if anything weird is going on under it? What's to the right of the frame there, on the other side of the stunted plant-- anything of interest?

jessica

There are more tomatoes on either side of the stunted plant, though planted about 3 feet away.

I've been searching the internet off and on all day, and the only other thing that describes some of it is "tomato curly top viroid", whatever THAT is. But I must admit that none of these rather esoteric IDs make me any more sure than not knowing a THING!

Anyway, I'm going to remove the plant tomorrow and replant a Rutgers there. And yes, I'll check the roots, too. I don't think it's nematodes in this clay soil, but who knows? I have six of the Rutgers I was planning to plant later in another spot. I'll plant the new Cuostralee with the five remaining Rutgers in the new spot.

I really wonder how many of us have plants languish or die and despite all our research, we cannot determine why. This is the first time in all my years of gardening that I've had a set-out tomato plant fail. It's really frustrating.

Hi anney,
Picture does not suggest Boron (B) deficiency.
B problems appear in the growing points of stem/flower/fruit; as regards the young leaves think distortion & vein chlorosis. (High pH, a lot of Ca & even sparse N can impinge B uptake.)
Consider your fertilizer used as possibly being a variable for that one plant's roots & you may have gotten a nutrient uptake failure.
When uproot it & see stunted rootlets the chance is you used a urea N fertilizer that messed up the plant's pH, Potassium (K) & etc., etc. (See 20th May post "Urea Anyone" on Container forum.)
It may be of further interest that applying excessive B, say to erroneously remedy a suspected deficiency, can be toxic to the plant; trace minerals are quirky.

Not "tomato curly top viroid." Not nematodes either.

Is the problem spreading"? If so, you may want to remove the plant. If not, why remove it?

As was said, the "problem" -- if that's what is is -- is more likely to be something common or a garden glitch rather some rare, and/or obscure, disease/disorder.

Jean

No, the problem doesn't appear to be spreading. It's just that one plant that was the same size when planted as the one behind it. But it's pretty obvious that plant isn't growing nor is it flowering, though the others are. It doesn't look like it will be productive, and I've been waiting for a week to see if it recovers and grows again. Instead, it's languished more and more. It's time for surgery!

GJ

Yes, I agree with you. If it isn't a disease, it must be some kind of nutrient problem that affected it and none of the other plants closeby. I didn't lime the bed this year or last year, and that's where Southern peas, a legume, grew. Tomatoes haven't been grown in that bed previously.