Bacteria Leaf Scorch – Xylella fastidiosa

Bacterial Leaf Scorch (Xylella fastidiosa.)

Bacterial leaf scorch (BLS) is caused by bacteria called Xylella fastidious. This disease affects some shade trees in late summer and early fall, causing uneven’ scorching’ of the leaf edges. The bacteria dwell in clusters called bio films in the xylem tissue. These bacterial ‘bunches’ clog the xylem and prevent water transfer, causing scorch symptoms.

What is Bacterial Leaf Scorch?

Shade trees are appreciated for their majestic stature and beautiful leaf displays. Bacterial leaf scorch disease poses a severe danger to the health and attractiveness of these plants. The symptoms may be subtle at first, but once the illness has taken hold, the tree is typically on the verge of dying. This disease has no therapy or bacterial leaf scorch management, but certain cultural activities may be taken to guarantee a lovely tree in its final years.

Symptoms and Diagnosis:

Premature browning of leaves in mid-summer is the first indication. Throughout the late summer and fall, the symptoms worsen. The leaf edges become dark, starting on the older leaves and expanding outward at the branch tip. A narrow yellow line separates browned, dead portions of the leaf from green tissue in most, but not all, afflicted plants. The tree’s browning leaves may fall off. The following year, infected trees usually leaf out, with the leaves on a few different branches becoming prematurely brown in late summer. For 3 to 8 years, the symptoms worsen until the entire tree becomes brown prematurely. Defoliation causes twig, department, and limb mortality owing to a lack of green, chlorophyll-producing leaves year after year.

Life Cycle:

Infected leafhoppers and spittlebugs spread germs by feeding on vulnerable host plants’ succulent, terminal shoots. As the bacteria move through the xylem channels, it becomes jammed, reproducing and infecting new regions of the tree. For insect vectors, there are no practical control measures. Cold-sensitive bacteria overwinter in sheltered places inside the tree’s xylem, and their populations gradually increase as the growing season unfolds.

Integrated Pest Management Strategies:

  1. Maintain the health of the plant:The illness has no known cure. Maintaining the health and vitality of sensitive trees can help them fight disease and live longer once affected.
  2. Maintain proper hygiene: Branches that have perished due to bacterial leaf scorch should be removed regularly. Infected trees at a critical condition of decline should be removed as well. Between pruning cuts, disinfect pruning tools with a 10% bleach solution.
  3. Plant resistant species:Avoid planting susceptible trees in places where bacterial leaf scorch has occurred.
  4. Injections of antibiotics:Injections of oxytetracycline root flare in the spring can lower bacteria levels and postpone symptoms by a few weeks. They are costly, must be reapplied every year, and the long-term effects of their usage are unknown. If you’re thinking of injecting your tree, you should talk to a licensed arborist first.