The time to trim your oaks & elms are when the trees are dormant. Generally this is between October and February. The reason behind this is that if the sap is not running in the tree because it is dormant, the beetle that affects these trees is inactive due to dormancy and is not interested in the cuts! An added benefit for pruning trees like Oaks in the winter is the opportunity to thin the canopies and reduce end weight on branches that break from the load of our snow or ice storms. Experience has shown that the trees we care for on a regular basis suffer less from storm damage than other trees in the same neighborhood. Winter pruning can have another important advantage, in that we can usually schedule the work much quicker. We are available to prune throughout the winter months
The oaks & elm trees are particularly vulnerable when they have been trimmed before their dormant season or have sustained damage to Oak Wilt and Dutch Elm Disease. When a non-dormant oak or elm tree has been trimmed or cut, the tree bleeds sap. The sap attracts tiny beetles that carry the fungal spores they picked up from other infected trees, dead logs and other debris and deposits the spores into an open wound. The trees active sap stream carries the spores throughout the tree. Branches begin to dye within months, and if the infestations are severe enough, even a mature oak or elm tree may be dead within two years.