The MU Plant Diagnostic Clinic continues its partnership with the Missouri Department of Conservation (MDC) Forest Health Program to offer FREE testing services for all common oak tree diseases in 2026. Thanks to the support of MDC Forest Health Program, we will continue studying the location and host species of oak diseases across the state, including Tubakia Leaf Spot, Bacterial Leaf Scorch and Oak Wilt. Meanwhile, we are also actively scouting for new or invasive diseases of oaks, such as Bur Oak Blight disease to better assist MDC and the Missouri Department of Agriculture (MDA) with managing forest pest problems.

Leaf spot disease of white oak. (Photo: Daria McKelvey, Missouri Botanical Garden)

If you suspect insect or disease problems are present on your oaks, we can identify the issue through sample testing at the MU Plant Diagnostic Clinic. First, submit 3-5 photos of your tree through the Digital Sample Submission System. Take photos of the tree from a distance as well as up-close pictures of the damage or disease you are seeing. MU plant diagnostic clinic staff will contact you regarding the submission guidelines for a physical sample depending on the tree health problems observed in the photos.

To submit a physical sample for oak wilt, please select leaves that are still green but show leaf scorch symptoms. Collect 20-30 leaves with the petiole (leaf stem) attached and pack them in a zip-top bag with a damp paper towel. Please collect 4-6 branch sections that are about 8 to 12 inches long, roughly 0.5 to 1.5-inch in diameter, and alive but showing symptoms of leaf wilt. Keep the samples cool, but do not freeze them. Samples that get hot during transit to the lab may not test positive for oak wilt.

For more information on sample submission, please visit the MU-PDC website.