Go ahead and cut it off, as it won't grow back together. The plant will heal the open wound, and be fine. As to the broken piece, I stuck a broken piece into some potting medium, kept it wet, and it rooted fine. Give it a try, even without the rooting hormone...

Bent? Yes. Partly broken? Possibly. Mostly broken? Nope. Just do as srjohnt said - cut it off and root the cutting. Strip off all the lower leaves and I cut to about 6" in length, bury the stem deeply and keep moist.

Dave

The weird thing (or maybe not so weird) is that I thought, given the fact that it'd broken sometime yesterday when temps were nearing the 90's, that the leaves would be totally wilted and sad by now with a deep break, and as of right now, all but one of the topmost leaves still feel and look normal. Either it's just such a large piece that broke off that there's enough moisture to sustain it for a bit, or the break isn't as bad as I thought.

If I give it another day to see what happens with the foliage, do you think it'll be too late if it does start to shrivel or wilt a bit? (Yes, I am way too optimistic sometimes.)

I've had a tomato plant nearly completely severed in an accident this year. I righted the stem and stuck a stake into the ground next to it. Make sure the two ends are touching (as if it were not broken. Use gardening tape to affix the stem to the stake and it may heal.

I saved a plant this way. The wound is completely healed and that part of the plant feels almost like a wood knot!

I've had severely bent stems survive if I splint them well. They didn't completely break open. However, if they got bent more times after that they died.

I have not had any luck rooting any cuttings/stems when they broke and I then cut them cleanly.

Alice

Update: some of the leaves are now starting to get wilty, but on the whole, the whole branch still looks pretty good. If I can get myself some soil today, I'll lop it off, and see what happens. If I can't, it will stay tied up against the main plant where it split, and I'll try again tomorrow.

I'm so happy for all the input. Gives me some hope that maybe... maaaaaaybe, it'll fix itself.

That happened to me and I just used some electrical tape and a splint to support it and it fixed itself. I also had a cutworm completely sever a plant and I just stuck in right in the ground, kept it moist and that also became a nice productive mater plant. Tomato plants are very strong, the only problem I ever had was blight. Last year was my first year growing a veggy garden.

I would cut it off and stick it in the pot or another pot with some potting mix, it should take root. I did it and now have a flower on my broken off branch:)

Good Luck,

Dusty

Cut the broken stem, stick it in a 5 gallon pot, and replant it when it roots in a few weeks. That one will get you past the late blight the earlier plants will suffer.

I have the same problem the stem got some tomatoes on it could I take the tomatoes off & cut the stem or leave the tomatoes on cause they not ripe yet

I've had mostly broken branches continue as if nothing was wrong, including growing new fruit and ripening them. It would be the first to start wilting when there wasn't enough water, but did fine other than that.

You can tape the branch together. Use strong tape. It will heal itself

I also keep a supply of electrical tape here and have successfully taped almost completely severed branches. I made sure to put a stake next to the severed arm for support and tie good.