Espalier Apple Tree Advice

[SpikeNaylor]

Hi all

I have two apple trees trying to grow as espalier.
They are planted against 6ft fence on top of 10ft concrete retaining wall, top 12 inches in ok topsoil, rest is sand. as far as I can tell.
Planted 2023 and grew ok for 1st year.
now in second year and both look ok but have an issue with them just to make sure ok or If I need to add something

any advice please

[Snoop Puss]

Hello and welcome, Spike.

Plenty of people here with fruit tree experience who'll be able to give you some advice. Are you able to post a photo or two of the underside of the curled leaves, so they can see if you've got a fungal or insect issue?

Plus, sand is maybe not an ideal environment for trees, as it drains very fast and the tap roots might struggle for water. What's the other side of the fence? Could trees spread roots that way too?

[ameno]

That's almost certainly leaf curl aphid, and a fairly bad infestation, at that. Check the undersides of the curled leaves, and you should see lots of grey aphids.
If you want to deal with it organically, they your best bet is to squash all the aphids you can on the underside of every leaf. Personally speaking, though, with an infestation that bad I would just use an insecticide. You can use an organic one, if you like; they seem to work just as well on aphids. Be sure to spray the undersides of the leaves, though. From experience, one dose is usually enough to see them off.

It might also be best to feed them up a bit. Indeed, since they are apparently on poor soil under the top 12 inches, it would be best to give them plenty of balanced fertiliser (growmore, poultry manure, fish, blood & bone, etc.) every spring.
As said above, they may also need watering, especially in dry weather.
What rootstock are they on? Usually M9 or M26 is recommended for espalier, however on poor soil it is usually best to go one size up to achieve the desired results, and the poor soil stunts their growth. An MM106, for example, is likely only to grow with the vigour of, and reach the eventual height of, an M26.