Bacterial leaf scorch (BLS), or bacterial leaf spot, is a disease state affecting many crops, caused mainly by the xylem-plugging bacterium Xylella fastidiosa. It can be mistaken for ordinary leaf scorch caused by cultural practices such as over-fertilization.
BLS can be found on a wide variety of hosts, ranging from ornamental trees (elm, maple, oak) and shrubs, to crop species including blueberry and almond.
An irregular browning leaf margin which may or may not be bordered by a pale halo.
Symptoms re-occur every year, spreading throughout the tree crown, eventually killing the host plant.
Xylem-feeding leafhoppers can transmit the disease bacteria. In general, any xylem-feeding insect can transmit the disease.
There are no known effective treatments for BLS, consequently, removal of affected plants is recommended.