Could you put up a photo of the whole tree plus a complete branch? I think it is more likely that, for some reason, there were no pollenating insects around at the time the trees flowered. Or, could they have been sprayed with something?

Hi, there are some varieties that only produce flowers and fruit biennially, so if you have these, you will only get fruit every other year, Derek.

Apple trees need to be pollinated by a different cultivar of apple than what you have. Not only do they need to be of a different variety, but the need to be in the same pollination group, i.e. flowers at the same time.

Did you have a good crop of blossom this year? If so, I think that the reason that you didn't get any apples could be to do with a lack of cross-pollination.

The reason you got a good crop of apples last year could be because bees and other insects just happened to cross-pollinate your trees from a suitable nearby tree. Maybe this year the bees didn't want to fly as far, found nectar closer to their nest, or some other reason.

If you know what the name of your apple tree is, then Google 'apple pollination groups' and you should be able to find out what varieties or cultivars are compatible with yours for good cross-pollination. When you find one, it's a good idea to get one so that you will be virtually guaranteed cross-pollination to both varieties year after year.

If you have had these trees longer than 2-3 years, and they cropped last year, it won't be a pollination issue. Mostly, curled leaves on apple trees indicate the presence of an insect of some kind, often aphids, but they wouldn't stop the tree from producing fruit. Did your trees actually flower this year?

At their original planting, I bought four trees; two of which were bought so that the pollination time would concur with the other two; Fiesta Minarette was the first two, , I forget what the name of the other cross-polinater was, but they haven't done badly in a 24" x 24" plastic tub for 26 years, have they?