We have recently had a Silver Birch tree branch cut near the main trunk and have noticed that it is now bleeding sap over 4 days later. Please can you tell me whether it is possible to stop it bleeding and if there is going to be damage to the tree.
I'm sorry to say that my first thought is "mmm, birch sap wine!"
I used to make home-made wines, but I never actually tried that one: I'm sure that there will be recipes on the internet.
It may damage the tree, since any opening in the bark can let in diseases. But birch are short-lived (relatively)trees anyway: it depends on your point of view whether this is a bad thing or not. If you are fond of the tree, then it isn't good! But when managing a woodland for wildlife, actively causing some damage can be desirable, to introduce new habitats.
I believe you can buy proprietary treatments from garden suppliers, but the problem should sort itself out anyway, in time.
I had to prune some branches of my silver birch in the past and it is worrying at first but the sap soon starts to set and seal the wound. Whilst I agree that a wound can let in disease, plum trees are normally prune this time of year so the sap flowing out of the wound stops fungus like silverleaf getting in.