The ability of a tree to heal itself quickly following pruning is important as it reduces the risk of infection, reduces the impact on tree growth, and improves the quality of its timber.
I’ve written previously about how to prune a tree and if you follow these guidelines correctly, the tree will be able to repair the tissue around the pruning wound or occlude the wound. Here are some pictures of walnut and cherry pruning wounds occluding, and the results when pruning is carried out incorrectly.
Three wild cherry images share in common the fault that all the branches removed were large in size. To make the situation worse, whoever pruned these managed to damage the tissue around the branch-bark ridge, probably by cutting too close to the top or side of the main stem.
Notice on one of the walnut images the hole in the centre of the former branch, as walnut has a chambered central pith – but that’s another story!