Black marks on tomato skin

[Primrose]

Can anybody suggest what may have caused the black marks, which look like dirty patches , which have been appearing on the skins of a lot of my Gardeners Delight outdoor tomatoes this year, particularly the lTer rioening ones. It,'s not blight, it's s not affecting the taste of the tomatoes and strangely has not appeared on the skins of the other tomato varieties I've been growing.
I was planning to save some of their seed for next year biutnnow wonder if that is wise in case it's some kind of disease rather than something that may have been weather/ temperature induced.

[PLUMPUDDING]

Could it be the sooty mould caused by aphids? Some of my tomatoes have it and it washes off.

[Beryl]

Blossom End rot is another possibility. Caused by uneven watering.

Beryl.

[Ricard with an H]

I have this on one-or two, mine doesn't look like blight on the basis of internet photo's i've seen.

Amongst this years disappointments have been my tomatoes, they don't taste like the ones I prefer which isn't their fault, I think I have a reasonable crop. Considering this has been the best summer I remember for a few years 50% of my crop are not going to ripen.

[cathytreat]

If you add the picture then it is easy for identify the disease.I think this is the Anthracnose( fungal disease).You can disposed all the plant and also use the proper pruning technique.I am not sure the disease because the picture is not available.I will share some best essays about the Anthracnose.