It’s time to stop pruning oak trees

The arrival of spring means it’s time to stop pruning oak trees! That’s right, if you love that oak tree in your yard, remember this important rule: Don’t prune mid-March through June! Oaks become more vulnerable to oak wilt a couple weeks before budbreak occurs in the spring. During this time, fresh wounds on trees can attract insects carrying oak wilt spores.

Oak wilt is an aggressive disease that can kill a healthy tree in the red oak group (pin, shingle, black, northern red, etc.) within a few weeks after symptoms are first noticed. Trees in the white oak group can also be infected but may take years to die from the disease.

If an oak is damaged or must be pruned in the spring, prevent oak wilt infection by immediately spraying or painting the wound with a tree wound dressing or asphalt-free latex paint. Do NOT wait to cover wounds as insects carrying oak wilt spores can arrive within minutes of the damage. This is the only situation where we recommend using a tree wound dressing, and treating wounds is not necessary during other times of the year. For more information on oak wilt, visit https://short.mdc.mo.gov/ZNT.