Tiny braeburns!

I am in a bit of a quandry over one of my apple trees.

I have four - bramley cooking, royal gala, cox's orange pippin and braeburn. The cox hasn't yet fruited, the other two fruit brilliantly, great quality and lovely taste but for some reason, the braeburn produces miniature apples! Crop yield is usually good, and they taste great, but they are teensy.

I've attached a pic of the last of this year's crop so you can get an idea of size. The tree itself is roughly 4ft and at least 10 years old - I got it from a friend three years ago, she kept it very toughly pruned as her garden is small. It's rooted in well, but is hardly growing and producing these dinky fruits. The gala came from the same situation and despite a huge fungus problem a couple of years before I took it, is growing and fruiting beautifully (braeburn was not touched by the fungus). The yield this year has been low too but that's most likely because it's been drowning in weeds - I've been physically unable to maintain the lawn due to injury last year so it has had that extra struggle (I have given it some multipurpose food a few times for a boost and am now getting on top again). But last year it was kept pristine, and same tiny apple and low growth problem.

Anyone any idea why it's doing this?

 

The gala is about 5ft, both are planted in my lawn and were in the lawn at my friend's house (her soil is heavy clay compared to my light sandy). She did prune them viciously, she told me this was to keep them tiny so her son could pick apples whenever he fanced one. The trunks are both about 6" thick and root systems are strong, smaller on the braeburn though.

When I took them I dug them out as wide as I could (so they'd still fit in my van) and transplanted them directly into my lawn, this was February 2011. Not the best way to do it but it worked! Friend said she'd always had titchy apples on the braeburn as well so I don't think it's connected to the move.

The other apples are huge and tiny - bramley is ~30 yrs old and fully grown, cox is only a couple of years old and only a few feet high, still in a pot.