thanks all, very helpful
Here are some pics of the sorry old apple tree in our garden. It's one of a pair, and we had a tree surgeon (a young guy) recently say it was done for, and would need to be cut down at some point. What do you think? This tree provided us many awful sour apples, and also broke my brothers arm, and also once perched a froggy on a branch, from which me and another naughty child forced it to jump from, into a bucket.... (it managed to do so, and we let it go free. Sorry for the former part) Over lockdown we realised what was up, too late perhaps. My mum also told me to harvest the last apple it would ever produce. So I decided to ritualise it and wait til the next day. It was the only red apple I've ever seen on that tree that I can remember. the next day it was gone, eaten by birds... or squirrels? So, I feel a responsiblity to post here to see if we can save it - can we?