[header] How to prune an elm tree [title] Prune only during the early spring to prevent elm bark beetles. [step] Many experts claim that the scent of pruned elm bark attracts beetles, which carry dutch elm disease. Only trim your elm tree in the early spring, preferably before march 31st if you live in the northern hemisphere. 
[substeps] Some areas have specific restrictions on the dates when residents are allowed to trim their elm trees. Contact your local government to check if there are regulations in your area.