Figure 1 Leaf Symptoms of Oak Wilt. Credit: Clinton Meinhardt

In partnership with the Missouri Department of Conservation (MDC) Forest Health Program, the MU Plant Diagnostic Clinic will offer FREE testing services for all common oak tree diseases in 2024. With this service, we hope to collect information on the location and host species of oak diseases across the state. 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.

Oaks are common trees in both yard and forest settings across Missouri, and several issues can affect the health of oak trees. Two oak diseases of major concern are Bacterial Leaf Scorch and Oak Wilt (Figure 1). Both diseases can kill oaks, with oak wilt being a fast-acting tree killer and bacterial leaf scorch appearing as a chronic issue that worsens over several years. Unfortunately, these diseases can also spread to other nearby oaks if not addressed properly. If you suspect either of these diseases is present in your oaks, the first step is to confirm the disease through sample testing at the MU Plant Diagnostic Clinic.

If you are interested in submitting physical samples of your oak tree, please first email 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 physical sample submission guidelines depending on the tree health problems observed in the photos.

For bacterial leaf scorch testing on oaks, 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. Keep the leaves cool. Contact the lab about shipping recommendations.

For oak wilt testing, 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. Contact the lab about shipping recommendations and timing.

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