Checking the TAMU problem solver......looks very similar to early or late blight. Were the spots on the stems mushy at all? Any spots on the leaves? It's good that you pulled the plant--be sure to sterilize anything that might have touched it.

Thanks for the reply.

The leaves of this plant all appeared to be relatively normal. The smaller, new leaves were all curled, but the larger established leaves seemed normal. The TAMU problem solver also seems to be a great resource, thanks for the heads up there. This problem does seem to match up with Early Blight. I may look into a fungicide of some sort if it happens on the other plants as well.

Thanks again.

Brown lesions look similar to the blight but not the same. The leaves looks as if damaged by a plant growth regulator, some of which are weed killers.