Diseases and Invasive Species

Bacterial Leaf Scorch Disease

Bacterial Leaf Scorch (BLS) is a disease that affects the water and nutrient conducting tissues of trees. Locally, it is most common in red and pin oaks. This group includes as many as 800 trees on Urbana public property. BLS may also affect elm, sycamore, London plane, sweet gum, hackberry, ginkgo and maple trees.

City arbor staff has already detected BLS in Urbana’s State Street area where a percentage of red and pin oaks are showing signs of extensive dieback. Unfortunately, the disease cannot be cured. Residents are encouraged to assist in trying to manage the disease by:

• watering during dry summer months
• minimizing root disturbance by not planting flowers or digging around the tree
• mulching the tree

Symptoms first appear on leaves in early to mid-summer and worsen as the season progresses mimicking drought or heat stress. Affected leaves may turn a yellow-green and then brown, usually from the outside of the leaf inwards. BLS usually begins with older leaves and spreads outward to leaves toward the branch tip.

If you suspect a tree has BLS and would like positive identification, you can take a portion of the branch with the symptoms to the U of I Plant Clinic after Labor Day. There is a $25 fee for analysis.

Learn more about BLS:

University of Illinois Extension Home, Yard and Garden Newsletter
University of Illinois Plant Clinic

Please help us in our efforts to stop this disease from spreading and destroying Urbana’s oak trees.