It looks like the remnants of damping-off or cutworm damage from here.

How large is the plant? I'm guessing less than a foot...

What I would do (if it's small enough) is actually cut it off just above the damage, then stick the top part into very moist soil. It should root in a week or so, and you can replant it. If it's larger, I'd take the top foot and any suckers I wanted and do the same.

Tomato cuttings root very readily, and it shouldn't set it back more than a week or so if it's young. That way you can avoid any question of whether the damaged stem can serve and support it as it grows.

--Alison

Hi Allison

Thanks for your input. The plant is actually close to 2.5 - 3 ft tall. The picture is deceptive. Since my post from yesterday the wound developed a whiteish mould/fungus.

We updated the website if you want have a look. Look for the "next" at the bottom
http://forums.gardenweb.com/forums/followup.cgi#
# I also posted in the regular forum (it's a bit busier over there) and got some feed back. could be ants or blight...

*sigh* I just we both survive this

lynda

Lynda

I see you have some suckers on the plant (stems growing in the leaf-crotches of the plant) so I'd echo torquill's suggestion about removing and rooting some of the lower suckers in case the plant fails. I think I'd do that first and then break off the stem above the injury, root and plant it, too.

You'd be awfully disappointed if the entire plant failed because of that injury, whatever caused it, when it got bigger and began producing tomatoes. This way, you're likely to get a healthy plant or two and have a good harvest.

In case it's helpful, below is a discussion conducted earlier about how to do it.

Here is a link that might be useful: Tomato Sucker Propagation