Bacterial leaf scorch (commonly abbreviated BLS, also called 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.

Hosts

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.

Symptoms

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.

Vectors

Xylem-feeding leafhoppers can transmit the disease bacteria.

Treatment

There are no known effective treatments for BLS, consequently, removal of affected plants is recommended.