Quick Summary
A bacterium known as Xylella (species: Xyella fastidiosa) is spread by piercing and sucking insects such as leafhoppers and spittle bugs, but most commonly sharpshooters. Xylella infects the Xylem tissue of trees, such as elm, oak, sycamore, mulberry, almonds, and maples, causing discolored “scorched” tissue.
Green sharpshooter, Family: Cicadellidae
What to look for:
- “scorched” tissue, similar to environmental scorch or salt burn, with leaf edges turning brown
- Clear edge between healthy and scorched, dead tissue. Very little intermediate yellowing
- Notable difference in bacterial scorch is the uneven scorch pattern compared to scorch caused by environmental stressors, which display a more uniform pattern
- Scorch spreads to different branches as the pathogen spreads over years
- Damage may not be noticeable at first because scorching may initially be limited to a small area
Bacterial leaf scorch
More Information and Resources:
UC Nursery and Floriculture Alliance. Disease Focus: Scorch disease caused by Xylella fastidiosa
UC IPM Pests in Gardens and Landscapes. Liquidambar, Sweet gum
UC IPM Glassy-winged Sharpshooter