trimming birch tree

Question

Itrimed my birch to late .and is lossing lots of sap

Answer 1

Birch Tree should be pruned in late summer.

Make sure you watch for signs of pest with the weeping fresh wounds.
Do not cover them, but I might suggest spraying the cuts with Neem Oil to reduce the risk of disease or pests.

https://www.gardeningknowhow.com/ornamental/trees/birch/cutting-back-birch-trees.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm