My cherry and plum patio trees blossom ok but when setting all small fruits drop off.

Question

Alongside pear patio trees which do OK.

Answer 1

I think both of these articles will help with your fruit drop problem:

https://www.gardeningknowhow.com/edible/fruits/cherry/cherry-fruit-drop-problems.htm
https://www.gardeningknowhow.com/edible/fruits/fegen/reasons-for-small-hard-fruit.htm