Hi don't know if anyone can help here. I'm a new gardener this year and am growing tomatoes in pots in a courtyard gaden. I have attached pics of 2 of my plants which from research on the net I suspect to have stem rot. There seems to be a lot of conflicting advice on what to do, so I thought I'd post here.

Apologies for joining and posting a question straight away, I will hope to be able to contribute as my knowledge grows.