Allotments 4 All

I have what looks like rust spots on the leaves of both my cooking and eating apple trees (which are next to each other) on the allotment. I have been taking the leaves off and disposing of them but more are coming - what is it please and do i need to worry? I have loads and loads of apples this year (last year hardly any so think the trees have become biannual).
Any help gratefully accepted, thanks

There is an organic tree wash from all garden centres.

You spray it on every year on Boxing day.

Due to restrictions on the use of products there is nothing else you can use.