Beech Leaf Disease

Beech Leaf Disease is a harmful disease for beech trees caused by an invasive worm-like creature called a nematode. It lives inside the leaves and buds of infected beech trees.

This disease causes leaf loss, beginning with the lower branches and moving upward. Within a year, it kills the buds, which results in the death of the tree. Beech Leaf Disease can impact beech trees of all ages, from saplings to mature trees.

Beech Leaf Disease affects the beech tree family. All beech species, including native American beech, European beech, and Oriental beech are susceptible to the disease.

Beech Leaf Disease first emerged in North America in 2012, beginning in Ohio, and has since spread rapidly to other states and Ontario, including in London. While all species of beech trees are susceptible to Beech Leaf Disease, some beech trees can resist the disease.

Signs and symptoms

Symptoms of the disease becomes obvious in summer (mid-June to September). The symptoms include:

  • Dark-green stripes or bands between the veins of leaves.
  • Thickened or leathery leaves that may be yellow, curled, or deformed
  • Leaves may drop early, and buds may fail to develop.
The leaves of a beech tree infected by Beech Leaf Disease

Preventing Beech Leaf Disease

There are important ways Londoners can help prevent this disease. 

  1. Monitor closely and keep a close eye on trees for signs and symptoms to catch the disease early.
  2. Avoid moving firewood between different areas as it might transport infected wood to new locations.
  3. Isolate affected areas to prevent further spread of Beech Leaf Disease.
  4. Refrain from moving beech seedlings, leaf litter from infected areas.

The Ministry of Natural Resources and Forests is studying Beech Leaf Disease in Ontario to isolate the nematode, understand how it is spread, find resistant trees, and create a management plan. The City of London is also supporting this work by surveying woodlands to understand the disease's impact and plan for its control.

Invasive species center

Last modified:Thursday, February 01, 2024