Can I prune an espalier apple tree in winter?

Hi. I am new here & not all all the most green fingered person you will ever meet. I have moved into a house recently & the garden has a 2 tier espalier apple tree which seems reasonably well established & bore a lot of healthy apples last year. There are  however about 20 or so vertical whippy branches, small diameter but about 3 or 4 feet tall. Is is feasibale to cut these back now, & if so by how much. All help & advice would be very much appreciated

Ideally, you would have removed or cut back these whippy branches in August. I'm assuming your tree produces its fruit on spurs......if espalier they would be.......and you prune in late summer to encourage fruit. I would cut back those whippy,shoots......they won't produce fruit.....now probably to just a few inches from the base. The idea is to produce short stocky shoots....spurs....along the branches and this is done by summer pruning.

Pruning of Apples can be done from the fall of the fruit until the breaking of the buds in Spring.
Summer pruning is to get rid of the unwanted young whips, in November you can shape the tree, remove any unwanted growth and prepare the Spurs.
Spurs are the shortened growth from a main branch usually cut back to just two buds, these produce the fruit.
So yes cut the young whips back down to two or three buds, if you want further tiers leave the main whip to grow on and then tie in the side branches on wires. Once you have the height you want then cut out the main whip.

Frank.

Thanks for your kind advice