Tree pruning needs to be done in a precise and correct way to avoid unnecessary stress, disease, rot and fungal attack. The correct pruning is to cut the branch cleanly and precisely at the right point. This enables the tree to heal the wound quickly and efficiently. If the pruning cut is too far out then the remaining stump will rot and spread disease. If it is cut too short then the healing cells in the joint will be removed and the tree will struggle to heal the wound, thus resulting in disease and fungal attack.
There are also optimum times of the year to prune various species of trees. Many trees can be pruned for a large part of the year but there are certain times of the year to avoid. During leaf fall in autumn, called abscission and when the trees leaf in spring. Commonly it was thought that winter was the best time to prune trees but now it is generally understood that the tree wounds from pruning heal slower in the winter and can make the tree more susceptible to disease.
It is usually required to wait until a fruit tree has dropped its fruits, apples or pears etc before pruning. Prunus species including cherries and plums are best pruned in the summer to avoid silver leaf disease.
During nesting season, which runs from March to as late as August in some cases, it is the law to protect the nest and young. Either eggs of chicks. We always do tree inspections at this time of year before starting a new job to make sure no occupied nest is disturbed. If a nest is found then that tree can be postponed until August or when the chicks have left the nest. Nests are usually always found in dense ivy and dense conifer trees. To try to inspect for nests in such a tree would disturb the nests and that is why I nearly always recommend postponing such a tree.