Could you have a critter tunneling under it? Any pics or history?

It could have bacterial wilt. If it revives after a watering, but then wilts again later, that could be a sign. You could cut a stem and put it in water. It will ooze white liquid and you will see hard brown bits in the stem. I hope it isn't this, but it's a thought.

Linda

Is it wilting or are the leaves curling? I've found that Black Krim is especially susceptible to Physiological Leaf Roll. It's not a disease and can be sometimes caused by excess moisture in the soil.

Send a pic when you get a chance, so we can get a better idea.

It is curling or as stated leaf roll, as Chris mentioned. Note the surrounding tom. plants are watered equally. Since I originally posted new offshoots (lower rite) have sprung up a bit healthier. I can try and post a more current pic. Should I consider cutting the curled leaves?

Different varieties can have different water needs and respond differently to stress. Some varieties are more prone to PLR than others. There might be something about that specific area of your bed that affects soil moisture as well.

I would just give this one more water than the others and see whether that helps.

In addition, check at the base of the plant around the soil line for any kind of damage and check leaves carefully for aphids or any other sap-sucking pests.

That is pretty severe PLR, but like I said, I have experienced PLR many times with Black Krim. The lower portion of my plant still has it, while all the upper foliage is normal. I don't think you should remove the curled leaves, because that would leave the plant without most of its foliage and won't necessarily fix the problem. Does your soil have a lot of clay? That could be a contributing factor, since PLR can be caused by excessive soil moisture and clay doesn't drain well. I saw that another possibility was if a high-yielding cultivar was given excess nitrogen.

I agree with Chris the PLR is really common in certain varieties. I can't speak for Black Krim, but some of my "regular leaved" plants will really curl and wilt, usually in the evening.

That being said, do you see any aphids/whiteflies on your plants? I doubt that's the cause, but it has happened to me before.

Your soil looks quite hardpacked to me, and kind of waterlogged below the plant. How much have you been watering? It's possible it's being drowned. Tomatoes, some more than others, really like it dry in my experience. If I water too much I get those exact symptoms. I hardly ever water them except when adding a little fertilizer.

EDIT: Oops, you said the other plants are being watered equally....so watering is out. Hmm