Symptoms associated with oak wilt usually begin as yellowing branches in the upper canopy of the tree. The oak wilt symptoms move from the upper branches downward. The leaves wilt from the outer margin inward so the base of the leaf will remain green while the outer portion of the leaves turn tan or brown. Oaks in the red oak family are most susceptible and usually die very quickly, while oaks in the white and bur oaks are more resistant and may survive for several years after infection. Vascular streaking (browning) of the xylem tissue is a good diagnostic symptom used to identify the disease. Positive identification of the disease can be obtained by sending a sample to the University of Minnesota Plant Disease Clinic (there is a charge).
For answers to your gardening, lawn, landscaping and wildlife questions, go to the University of Minnesota Extension web site or contact the Benton and Stearns County horticulturist at 968-5077 in Foley or 255-6169 in St. Cloud. If Foley or St. Cloud are long distance, you’re welcome to call to Foley at 1-800-964-4929 or to St. Cloud at 1-800-450-6171.
Do you have an active interest in gardening and a desire to share your interest with others? If so, consider becoming a master gardener and join the active master gardener group in Benton County. For more information, go to our website or contact the Benton County Master Gardener Coordinator at the numbers listed above. The St. Cloud numbers are the most direct connection.