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 2025. Thanks to the support of MDC Forest Health Program for promotion, we hope to continue to study the location and host species of oak diseases across the state, especially Bacterial Leaf Scorch and Oak Wilt (Figure 1). Meanwhile, we are also actively scouting for new or invasive diseases of oaks to better assist MDC and the Missouri Department of Agriculture (MDA) with controlling forest pest problems.

Figure 1 Leaf symptoms of oak wilt.

If you suspect disease problems are present on your oaks, the first step is to confirm the disease through sample testing at the MU Plant Diagnostic Clinic. Please first submit 3-5 photos of your tree through the Digital Sample Submission System ($10 service fee waived for oak sample). 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 physical sample submission guidelines depending on the tree health problems observed in the photos.

To submit a physical sample, 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 Ziploc 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 the fungus. In the end, please contact the lab about shipping recommendations.

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