Didymella on tomato plants

Hello folks!

Newbie here. This is my first year with a garden.
Growing some Principe Boghese tomatoes.

Unfortunately, due to my naivety I ignored the brown patches on some of the stems as they still had other healthy stems with fruit on. Suffice to say it's spreading and I now reckon that about 15 of my 20 plants are affected.

Having googled I'm pretty sure this is Didymella. I searched on this forum but didn't find any threads. Any advice? Do I rip up the diseased plants and hope the last few survive.... or do I spray... and if so, what with??

I'm a beginner!

Thanks

 

Are we talking Blight here?
Tomato blight is the usual problem in wet summers.

If so, I find the only spray that has some effect is copper fungicide

 

Dunno if it's the same as blight?!

It looks the same as this:

 

Well blight is normally black, but it probably has the same effect.

The plant dies if untreated and seriously affects the crop.