Bacterial leaf scorch

Bacterial leaf scorch is a disease state affecting many crops and ornamental trees, caused mainly by the xylem-plugging bacterium Xylella fastidiosa, whose different subspecies target different plant hosts. Affected species include ornamental trees such as elm, maple and oak as well as commercially important crops like blueberry and almond. The disease produces an irregular browning of the leaf margin, sometimes bordered by a pale halo, recurring and spreading through the plant's crown each year until it eventually kills the host. It is spread by xylem-feeding leafhoppers and other xylem-feeding insects, and because no effective treatment exists, removing infected plants is the standard response. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/