Horticultural aide memoire No. 45: Prune maples
Many trees and larger shrubs are prone to bleeding great quantities of sap if they are pruned in the spring. Among these are the members of the genus Acer, which includes maples of every sort from the giant sugar maple to the delicate forms of the Japanese maples such as Acer japonicum and A. palmatum. Any cutting work on these can be carried out now that dormancy has set in. The same advice applies to cherries, birches and magnolias. Resist the urge to lop and chop as this merely disfigures: confine your slicing to neat removals of awkward branches.