Oak wilt, a deadly fungal disease for oak trees, was discovered in six new locations in New York last year, according to the New York State Department of Environmental Conservation (DEC).
This disease can be spread by beetles that are attracted to freshly cut or injured trees, says the DEC. Pruning in winter protects oaks from becoming infected.
Prune oaks between October and February, not during the growing season.
The benefits of winter pruning include:
Diseases are rarely spread during this time, since insects and fungi are inactive.
A tree's branch pattern and damaged limbs are easier to see without leaves.
Leafless cut branches are lighter and easier to carry.
Nearby plants are less likely to be damaged by falling branches and trampling.
Removing weak and damaged branches before heavy snowfall reduces additional breakage.
Trees pruned in winter respond more vigorously in the spring, putting out new growth.
How oak wilt spreads and killsThe oak wilt fungus clogs the trees’ transport vessels, cutting off water and food from leaves and the rest of the tree.
One way oak wilt spreads is when fungal spores hitch rides on insects. Sap beetles, one of the main culprits, are very attracted to fresh tree wounds. Pruning oaks during the growing season greatly increases the chances of insects infecting them with oak wilt.
Another precaution is, 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.
For more information, call the DEC Forest Health office at 1-866-640-0652, or email photos of tree symptoms to: firstname.lastname@example.org.