[Munchkin]

I have one san marzano tomato plant in my greenhouse and it still has green tomatoes on it. Great! however, I think it's diseased and a big part of the stem is black and rotting looking. This is supposed to be a perennial and I don't really want to throw it out as it's my only one and it still has green fruit. If I just leave it in there could it affect my other plants? What should I do with my poor plant?

[mumofstig]

Tomatoes are not perennials, they will die in the cold.
It sounds as if it has blight anyway, so pick the green toms to ripen indoors and dispose of the plant.

[Munchkin]

oops I meant to say indeterminate. I always get confused between indeterminate and determinate.

[Kleftiwallah]

Determinate and indeterminate refer to the ripening of the fruit on the plant.  One ripens all together and the other's fruit ripens over a much longer period of time.    Cheers,   Tony.

[Munchkin]

LOL
Like I've mentioned in other threads, I'm such a noob

[mumofstig]

Determinate/indeterminate actually refers to the way in which the plant grows, although this does tend to lead to the cropping patterns that Kleftiwallah describes.

Indeterminate plants grow tall with a fruiting 'branch' growing from the stem which then continues to grow upwards and then produces the next one. It will continue to do this until the weather or you decide it is tall enough. The main point is that the growing of the flowering stem does not stop the plant growing upwards.

Determinate plants grow many stems but each stem will stop growing when it produces flowers, this determines that the plant will stay bushy rather than grow tall.

[solway cropper]

to get back to Munchkin's original question.

I'd be inclined to pick off any un-diseased trusses and hang them up somewhere warm to dry. I've just finished ripening the last of my toms by hanging up the trusses in the greenhouse. If the plant is diseased don't put it on the compost heap but burn it or bung it in the council green waste bin.