While you can prune many kinds of trees in spring and early summer, don’t prune oak trees now.
The New York State Department of Environmental Conservation (DEC) recommends holding off on pruning oak trees until winter to protect them from oak wilt, a deadly tree disease.
Oak wilt can kill trees in as little as four to six weeks and is one of the most destructive tree diseases.
The video, ‘Winter Pruning For Oak Wilt Prevention’ (two minutes long) highlights why it’s important to prune oak trees from October – February instead of during the spring and summer, if pruning is needed.
Pruning during the winter can protect oaks from becoming infected because the beetles that spread the disease are dormant. These beetles are active in spring and summer and are attracted to freshly cut or injured healthy trees. Pruning in the spring and summer puts oaks at risk of contracting oak wilt.
Here are some things you can do to protect your oak trees:
- Prune oaks between October and February, not during the growing season.
- Follow existing regulations and quarantines meant to protect our trees and forests.
- Don’t move firewood. Firewood can transport oak wilt and other deadly pests and diseases to new areas.
- Learn to identify the symptoms of oak wilt, which include discoloration around the entire leaf edge and sudden loss of a substantial portion of leaves during the summer.
If you have specific questions, contact the DEC Forest Health Office at 1-866-640-0652 or email your photos of tree symptoms to firstname.lastname@example.org.
Get more information on pruning ornamental trees and shrubs here from Cornell Cooperative Extension.