Allison, H. (2022). How to identify the American beech tree. [Graphic Art]. Treehugger. 

American Beech

American beech is a common, broadleaved, deciduous tree. It has a smooth, gray bark, papery leaves, and long buds.

Its native range includes most of the eastern United States and the southeast edge of Canada. In Michigan, it is most dense in the northern Lower Peninsula and eastern Upper Peninsula. Beech trees provide a variety of benefits to humans,  wildlife, and ecosystems, including ornamental varieties, a diverse forest structure, and the production of bountiful beech nuts.

Origin

Beech leaf disease (BLD) was first observed in Lake County, Ohio in 2012. Since then it has spread northeast into Maine, and northwest through Ontario. It was first observed in Michigan in 2022.

BLD Distribution as of December 2023

Symptomatic leaf

Symptoms

BLD is identifiable by its primary symptom: dark green bands of thickened tissue between the leaf veins. These symptoms can eventually progress to shrinkage and curling. These symptoms often appear on branches with healthy leaves, because the damage occurs during leaf development.

Severe cases eventually lead to a decline in leaf production, presenting as bud suspension and bud abortion. Ultimately, the loss of leaves can lead to tree mortality. Sapling mortality has been observed within five years and mature tree mortality within seven years of infection.

Cause & Transmission

BLD is linked to the presence of a nematode, a microscopic roundworm, that embeds itself in the leaf buds. How the disease moves from tree to tree is still unknown. There are many theories of transmission from moisture to birds,  bugs, and even humans!

BLD does not only affect American beech. Many varieties of beech, such as European beech and Oriental beech, are also affected.

Microscopic photo of Litylenchus crenatae mccannii. From: https://doi.org/10.1111/efp.12580

What You Can Do

As with all threats to forest health, the best thing you can do is avoid moving the causal agent!

• Brush your boots if you are traveling from one beech forest to another.

• Avoid moving leaf litter.

• Clothes, like hats and shirts, can come into contact with low-hanging leaves. These should be washed at similar times to brushing your boots.

• If you see beech trees affected by beech leaf disease, take one or more photos and make note of the location, date and time of the observation, and report to: [email protected].

University of Michigan Impact

The School for Environment and Sustainability at U-M is conducting a long-term impact study on Beech Leaf Disease (BLD). The novelty of BLD raises critical questions: How will forests change as beech health declines due to BLD, and at what rate does this happen? What environmental factors are related to BLD symptom severity? These long-term impact studies identify plots where changes in forests and trees can be observed over many years. In the summer of 2023, twenty-one plots were installed with plans to revisit and install more in the future.  MBGNA staff regularly monitor the beech trees at Nichols Arboretum, Matthaei Botanical Gardens, and Horner Woods.