Old trees generally look after themselves for about 40 years, with the only required intervention being an annual pruning.
However, there are times when extra help from yourself can assist the tree and yield a better crop.
On my allotment, a grease band is a must. not only does it stop codling moths which lead to maggoty apples but they also stop ants from protecting aphids. As a result the ladybirds get to the bugs and the whole allotment benefits.