Bacterial Leaf Scorch of Oaks
Bacterial leaf scorch on pin oaks and red oaks is widespread and severe here in eastern Pennsylvania.
Leaf scorch describes the death of tissue along the edge of the leaf and can be the result of various causes. In the case of bacterial leaf scorch of oaks, it is caused by bacteria that invade and plug‐up the water-conducting vessels in the woody parts of the plant.
The bacteria that causes oak leaf scorch is spread by various sucking insects including leafhoppers, treehoppers and spittlebugs who, by themselves pose little threat to the health of the trees. As these insects feed, they pick up the bacteria from infected trees and spread it to healthy trees.
Symptoms usually show up in mid‐to‐late summer, and affected leaves may curl up and drop prematurely. As the infection progresses over several years, branches die and the tree declines, eventually to the point where removal is necessary. Depending on the particular tree and/or its environment, decline may occur quickly or slowly.
The only effective management strategy for this disease involves annual truck injection of the antibiotic tetracycline. It will temporarily alleviate the symptoms during the year of injection,but does not cure the tree of the disease. Symptoms will reappear in years when no injection is performed.