Tomato trouble?

Hi people, some of the the stem on my best gardeners delight plant has turned black but all the other plants are ok, should I be worried or not? thanks Kev

If you do nothing else, put the affected plant away from the others until you find a solution.
Dark stem patches can be botrytis, but that colour is usually grey.

Heavens!!! It looks suspiciously like early blight which is VERY early for up where you are.
Anyone else have an idea?
My toms are just getting going and some are just starting to flower so if blight's started I've probably lost them all like last year......