Posted August 12, 2025

If you have beech trees, you may be wondering "what's wrong with my beech trees?" After all, these hardy trees can last for centuries. The answer may be beech leaf disease (BLD).

Relatively new to the United States, beech leaf disease affects only beech trees. While it poses no risk to humans, it can lead to severe decline and eventual death in all species of beech trees. Treatment of beech leaf disease is essential to keep your trees vibrant and healthy.

Beech leaf disease is believed to be caused by a microscopic roundworm (nematode) that infects leaf buds. While it does not invade the tree's woody tissue, its effects become visible in the leaves. Infected leaves show distinct opaque banding—areas that may become thickened, hardened, discolored, or yellowed. Over time, this leads to defoliation, starting at the lower branches and moving upward. As the disease progresses, leaf buds are compromised, branches die back, and the entire tree can ultimately perish.

Smaller trees can succumb to BLD within 1–2 years; larger, mature trees may survive for 6–10 years after infection.

Researchers believe the nematode responsible is not native to North America. Once it enters the leaves, the adult roundworms migrate to the following year’s buds, typically from midsummer to early fall. The worms are thought to spread via birds, moths, wind, humidity, and rain. BLD has been detected in New Hampshire within the past three years.

Unfortunately, trimming or pruning does not help infected trees. The most promising treatments involve specific fertilizers and fungicides, applied biannually. Underplanting with alternative tree species may also help preserve the forest canopy, as healthy beech trees can live 300–400 years when not affected by disease.

If you're interested in treatment for beech leaf disease, contact Collins Tree Service. Our certified arborist can assess the situation and discuss appropriate treatment options.