BACTERIAL LEAF SCORCH (BLS) of hardwood trees, shrubs, and herbaceous plants, is caused by the bacterium, Xylella fastidiosa, carried by small insects such as leaf hoppers and sharpshooters. BLS has been very damaging to red oaks in Delaware and the Mid-Atlantic states for over 15 years. Northern red oak and pin oaks under environmental stress are most susceptible. Symptoms include marginal discoloration or scorch of leaves in late summer or early fall, often with a yellow or dark band on the inside edge of the discolored area. Symptoms are similar to those caused by drought or root issues that interfere with flow of water and nutrients. Plants may not develop symptoms for a year or two after infection, but then thinning of branches occurs and trees die within 5 to 8 years. Infection is confirmed with a lab test for a fee; please arrange to have samples tested by contacting the UD
Plant Diagnostic Clinic. There is a $20 fee for BLS testing. To manage, maintain good tree vigor, and remove infected trees. A UD fact sheet has more info: http://extension.udel.edu/factsheets/bacterial-leaf-scorch/
NFG 9/1/2017
