MO Tree Health News: March 9, 2016

It’s time to stop pruning oak trees! Remember the rule for oaks, “Don’t prune mid-March through June”. Oaks become more susceptible to oak wilt a couple weeks before budbreak occurs in the spring. Fresh wounds at this time attract insects that spread the disease.  

Oak wilt is an aggressive disease that can kill a healthy looking tree in the red oak group (black, northern red, pin, shingle, etc.) within a few weeks after symptoms are first noticed. If an oak must be pruned or is damaged in the spring, immediately spray or paint a tree wound dressing (available at garden centers) on the cut. Do NOT wait. This is the only situation where we recommend using a tree wound dressing.For more information on oak wilt, see our Oak Wilt Forest Health Alert.  

Use a commercial tree wound dressing on pruned or damaged oaks through June. Photo courtesy of Missouri Dept. of Conservation.