* I pruned them hard last year and destroyed the wood I removed. *
They
are fairly small trees ... would you suggest I cut them down and start again
later when I am around more often?

Many thanks Jake! *You have given me a much better idea on how to deal with
the problem

Best

O
--http://www.shop.helpforheroes.org.uk/

OK, a lot of ideas for you to think about, poor polination gives early
drop of un fertilised fruit, drought will result in more falling fruit
but I think your problem is to much fruit on the trees, thin the fruit
hard just before you go away, removing all but the best.
You will often find apple trees shedding fruit a few weeks before the
fruit is ripeif there is to much for the tree to carry to term.
Now regarding the tree that croped heavily then next year nothing, the
poor thing is exausted and has to rest for a year, it is common fo
fruit tree to crop in alternate years.
Again when the tree is carrying a heavy crop thin it hard.
Think of it like you running as fast as you can for a hundred yards or
so, you then have to stop to get your breath back, but if you just jog
along you can keep going.
David @ the wet end of Swansea Bay.