Bacterial Leaf Scorch Can Torch Landscape Trees

Kentucky’s landscapes are populated by many trees that are susceptible to bacterial leaf scorch. This disease may not kill trees instantly, but over time, it can have devastating effects. Pruning and reducing stress can prolong the life of infected trees; however, there are currently no methods to prevent or cure bacterial leaf scorch.

Bacterial Leaf Scorch Facts

  • Infected trees exhibit premature leaf browning (Figure 1), marginal necrosis, and defoliation. In subsequent years additional branches will present the same symptoms until the entire tree becomes prematurely brown (Figure 2).
  • Symptom development typically occurs in mid- to late summer
  • Symptoms of bacterial leaf scorch can resemble abiotic/stress, so confirmation by a diagnostic lab is advised.
  • Trees such as sycamore, maple, and oaks are susceptible. Pin oak and red oak are the most commonly reported hosts in KY.
  • Caused by the bacterium Xylella fastidiosa
  • Spread by leafhopper and treehopper insects.
Figure 1: Premature leaf browning of a pin oak tree branch infected with bacterial leaf scorch. (Photo: John Hartman, UK)

Figure 1: Premature leaf browning of a pin oak tree branch infected with bacterial leaf scorch. (Photo: John Hartman, UK)

Figure 2: Pin oak tree that has turned entirely brown prematurely from many years of bacterial leaf scorch infection. (Photo: John Hartman, UK)

Figure 2: Pin oak tree that has turned entirely brown prematurely from many years of bacterial leaf scorch infection. (Photo: John Hartman, UK)

Management Options

There is no cure for bacterial leaf scorch, and trees will eventually die once infected. The following suggestions may help preserve the appearance and life of diseased trees:

  • Prune newly infected trees to preserve appearance.
  • Water trees in the heat of summer to reduce stress.
  • Tree-injections can be costly and do not cure the disease; however, they may prolong the life of the tree.

Replace infected trees with species that have shown resistance to the disease. Suggestions include:

  • European beech
  • Kentucky coffeetree
  • Shagbark hickory
  • Common sassafras
  • Tuliptree

Additional Information

 

By Kimberly Leonberger, Extension Associate, and Nicole Ward Gauthier, Extension Plant Pathologist

 

 

Posted in Landscape Trees & Shrubs