Insects, Pests, Diseases & Weeds
Bacterial leaf scorch is a chronic disease caused by a bacterium, Xylella fastidiosa, that grows in the xylem of the tree and physically clogs these water-conducting vessels. As the bacterium multiplies, water transport becomes more limited. The tree suffers water stress, especially in mid to late summer, resulting in leaf scorch; a browning or discoloration of the margins of the leaves with interior portions of the leaves near the veins remaining green. The bacterium is spread by leafhoppers, spittlebugs and other xylem-feeding insects.
"SP661 Bacterial Leaf Scorch in Landscape Trees," The University of Tennessee Agricultural Extension Service, SP661-15M-9/05 R12-4910-051-006-06 06-0074, http://trace.tennessee.edu/utk_agexfores/31