Pruning Fruit Trees

Apples and pears need to be Winter pruned. I do mine in November. Stone fruit plums cherries etc should be Summer pruned, that is after cropping.
I don't use sprays so I cannot help you there.
Happy gardening

Plums specifically should be pruned by mid August - at least checking with out local tree nursery man that is what he told me as we need to prune one.

Depending on what you mean by a lot of grubs (in the apples themselves?) you could buy a pheremone trap which works for the moth that lays eggs which then invade your fruit - they used to be available at good garden centres, hopefully still are. It's like a sort of box sized canvas, open sided tent which hangs in the branches. Very effective.

These traps work really well for us. Only spray I use is Copper sulphate against Scab, reasonably organic.