Bacterial Leaf Scorch (Xylella fastidiosa) is a pathogen of concern economically and ecologically in both urban and rural forests. The bacterium disrupts the flow of water and nutrients from the infected trees roots to its foliage. It is often transmitted from tree to tree through an insect vector. Symptoms usually show up around mid-summer and can be mistaken with drought and water stress. Though it usually takes several years if the conditions are right and the infection persists it can kill a tree.
Fairly widespread throughout the US but largely concentrated in the lower Southeast quarter of the US, form Florida up to the Mid-Atlantic states and out to Texas.
Many species are susceptible in the Eastern United states including: oak, sycamore, elm, mulberry, and maple. Though this species is often associated with shade trees many ornamental trees, shrubs, grasses, annuals, and perennials are susceptible as well.
The presence of Bacterial Leaf Scorch can be visually identified by a irregular, marginal necrotic leaves that my have reddish or yellow halo. These symptoms can usually be found in mid- to late-summer on leaves in one or more branches in the trees canopy. The infection can spread to more branches over a period of time stressing the tree or eventually killing it altogether. The speed at which this occurs will depend on the overall health and vigor of the tree and other insect, disease, or environmental stress factors. Proper identification may have to include laboratory analysis.
Not much can be done to save an infected tree. To prevent the spread and slow Bacterial Leaf Scorch: proper sanitation of tools should also be used when pruning. Infected trees should be removed and nearby healthy trees should be watched closely. Stresses such as insects and drought should be managed to prevent any spread.
Prompt removal of diseased trees and sever root grafts between healthy and infected trees.
As always keeping trees properly pruned, managing nutrient levels in the soil, and preventing stress are the keys to maintaining
For a pdf copy of this factsheet: Bacterial Leaf Scorch