Shade Trees Being Hurt By Plant Disease

Bacterial leaf scorch is reportedly severely affecting U.S. trees grown to provide shade, help clean the air, reduce noise, and improve aesthetics.

Plant pathologists with the St. Paul, Minn.-based, American Phytopathological Society say the plant disease known as bacterial leaf scorch affects such shade tree species as the American elm, red maple, sweet gum, sycamore, and several oak species. The disease has been found in street plantings, small woodlots and landscapes across the eastern United States, as far west as Texas.

Ann Brooks Gould, associate extension specialist at Rutgers University, says current loss of value plus replacement costs for older trees affected by the disease is about $8,000 per tree.

BLS is caused by a bacterial pathogen, Xylella fastidiosa, which is spread by insects. Symptoms of BLS are similar to those caused by environmental stresses, resulting in the disease being often overlooked or misdiagnosed.

According to Gould, management options of BLS in urban trees include maintaining plant vigor, removing infected trees and branches that have died from the disease, avoiding planting highly susceptible trees and designing new tree plantings with a diverse complement of species.