3 years ago I bought 2 apple trees (Bramley and Herefordshire Russet) and have since trained them as espaliers - both now growing their third layers. Both trees have done well and blossom/fruit set has been good this year. However the Russet has a large area of canker 'damage' on the main trunk just above the first layer. It affects about half the circumference. The growth above looks healthy - I have googled the problem and am relieved to read that this will not necessarily kill the tree. However should I cut the damage out of the tree, ie above the first layering, or leave it and see how the tree copes with it? If I do cut out the canker, will the tree re-grow so that I can continue with the espaliering.
Any advice or opinion would be appreciated. Thank-you.