Urgent tomato advice needed

Help, this has appeared on the stem of one of my largest tomatoes. I have lots of tomato plants and so need to know whether it is what I think it is and how infectious it is i.e. should I carefully rip the plant out today?

Please advise.

 

Could be botrytis caused by where it's been rubbing against the stick.

 

How infectious is it? Should I hack the plant down today so it doesn't spread, or could I just cover the infection with copper sulphate and leave it (to die slowly and so get more fruit off it). I had some infected plants last year and it took a while before the infection really took hold, so I got a load of fruit off them. But this year, I'm mostly just growing tomatoes and salad leaves so don't want to risk half my crop. I'm very mindful that it's about to chuck it down and fungal spores will go everywhere.

 

Hessayon says to cut out infected area and dust with Carbendazim, what ever that is

 

The rot spread and the top started to wilt. I hacked the plant down at the weekend and rescued the large tomatoes. the rest went straight into the green bin. No signs of the same thing on any other plants. Yet.