What oak wilt is
Oak wilt is a fungal disease that kills red oaks (the pointed-leaf group) very quickly and white oaks more slowly. Sap-feeding beetles carry spores from infected trees to fresh wounds on healthy ones.
The safe pruning window
Plan oak pruning for late fall through winter. If you must cut or a storm breaks a limb between mid-April and July, seal the wound with tree wound dressing or latex paint right away.
Signs of oak wilt
- Leaves browning from the edges in summer
- Leaves dropping while still partly green
- Sudden canopy decline in one tree, then neighbors
- Fungal mats under bark in the following spring
Moving firewood
Do not move oak firewood from a wilt-killed tree. Spore mats can form under the bark the next spring. Talk to us or your county forester about safe handling.
Questions
Can I prune an oak in summer?
Avoid it from about mid-April through July. If damage forces a cut, seal it immediately.
Does this apply to all oaks?
Yes, treat every oak with the same caution, though red oaks are the most vulnerable.
Need help?
We offer tree trimming & pruning across southern Wisconsin. Request a free estimate or call (608) 844-1385.