This serious disease can slowly kill mature trees over the course of about a decade and unfortunately, has no cure. Insects such as leaf hoppers carry the bacteria from one tree to the next and inject the pathogen into the leaves of a new host while feeding. Once the bacteria begins to grow in the new host is spreads from leaves to small stems and eventually into larger limbs. The bacteria acts very much like a plaque in your arteries and clogs up the conductive tissue of the tree until water and nutrients can no longer be transported to those parts of the tree and they shut down and die.
Bacterial leaf scorch (BLS) mainly affects trees in the red oak family (red, black, pin, scarlet, etc.), but has been discovered in other species as well including Norway maple, Sweetgum and Sycamore. It is a slow- moving disease that causes a significant amount of dieback until the tree is a hazard to public safety or an eyesore that needs to be removed. While there are some treatment options that can prolong the trees life and keep it aesthetically attractive, the disease can only be managed, not cured.
Early signs of infection are a yellow-orange fall color arriving in August on several smaller branches. As the heat and drought stress of summer set in the conductive tissue of the trees become clogged and start the process of autumn leaf drop. Each year larger dead limbs appear in the crown and remain evident year-round. Early detection and treatment are necessary to have any long-term treatment of the tree be effective. Testing is done in August and September and treatment via a trunk injection is done the following spring.