Benefits of Pruning Oak and Elm Trees in the Winter to Early Spring
With winter in full effect and the leaves all gone, now is the time to trim your Oaks and Elm Trees.
Winter Pruning Reduces the Exposure to Pests and Diseases, Two such varieties that should only be pruned in the dormant months are Oak and Elm Trees, which are susceptible to fungal infections like Oak Wilt and Dutch Elm.
Oak wilt is caused by the fungus, Bretziella fagacearum. The fungus grows through the infected tree’s water-conducting system, causing the tree to wilt and die. Oak wilt is introduced to an area by sap-feeding beetles that carry oak wilt spores to fresh wounds. Spore-bearing fungal mats develop under the bark in the fall or spring following the death of the infected tree.The sap-feeding beetles are attracted to the fungal mats and can transport oak wilt spores to fresh wounds or to recently cut oak stumps. Once in an area, the disease spreads to nearby oak trees through interconnected root systems, creating an expanding pocket of dead oak trees.
Dutch Elm disease (Ophiostoma ulmi and Ophistoman novo-ulmi) works much in the same way; by attacking an elm’s vascular system. It too is spread by sap-feeding beetles, who often lay eggs in dead or dying infected elms. When adult beetles emerge in the spring, they will migrate to healthy elms nearby, spreading infection.
Since dormant trees do not produce sap, and sap-feeding beetles are not active in the colder months, they are much less likely to invade new pruning cuts to spread disease.