Bob Hobden wrote:
What kind of infestation is that? What has caused it?
Agree with everyone else, and as they say, inconsistent water supply is said
to be the cause however a few of our first ones out on the allotment are
also showing it and that cannot be inconsistent watering.

Your allotment didn't dry out at all during the really hot spell earlier
this year?

I've found certain varieties are a lot more prone to it than others. Cherry
tomatoes never* get it. Yellow ones don't seem to, either. But every time
I get a nice 'new' variety and I only have a handful of seeds and half of
them die and I only end up with one strong plant - /they/ get it! :-(

(so far this year, the 'noire' tomato has lost all but 1 fruit, and the 1
that didn't have it went rotten before it was eaten! - and the beefsteak-
like tomato, which I wasn't even aware I was growing, and I really ought to
find my list of what everthing is, that has had it, too)