We have a 35 yr old orchard and have a pro in every.
Prune elms during winter to avoid attracting the beetles, which can carry DED. True, Princeton has resistance to this disease, but precautions still are warranted.
The best time therefore for elm tree pruning is early spring ahead of the growing season. This timing allows good time for the wounds to close so the tree has plenty of time to rebuild its strength.
The petal-less flowers appear before the leaves and are borne in clusters on jointed stems.
Thorough pruning is advisable on a once every three years basis, with minor pruning every year. Added vigilance is crucial in areas where Dutch elm disease is prevalent so that dead or dying branches are removed in Estimated Reading Time: 6 mins.