Grow Your Own Magazine

I am stumped. I took a superb course through our agricultural dept (locally in Germany) on everything to do with fruit and gardens regarding cutting, fertilizing, pests, sicknesses etc etc but I have a problem which I can't resolve and the expert has retired and has no replacement (typical of government when they want to save money).

Here I am training espalier fruit trees and have some wonderful branches nicely developing out and up and AAAAARRGGHHH something has eaten off the growing top around 2 inches and it is now dangling down by a thread of stem! Yesterday was perfect, today is bent. Nothing to see. No insect, no insect traces, just a perfectly clean horizontal cut (not quite through) which is brown rather than dried green from a shear cut.

Has anybody seen something like this and what can it be?

Could be a mouse or a bird (such as a bullfinch) I suppose. Have hou a bud that y ou can train to take its place ?