Beech Leaf Disease: Causes, Prevention, and Treatment Options

Beech Leaf Disease (BLD) is a fatal tree disease that primarily attacks American beech (Fagus grandifolia) trees. These trees are native across much of the northeastern United States, are popular in yards, and a common sight in our forests. BLD is a relatively new disease and has only affected us in the Hudson Valley for a few years.

Though we are still learning about BLD and its causes, homeowners need to know the signs and what to do when it manifests in their trees. In this article, we examine the causes of BLD, the typical symptoms, and what you should do to prevent and manage BLD.

PRO TIP: BLD isn’t the only disease you need to watch out for in the Hudson Valley. Check out some of our other articles detailing the typical pests and diseases we see in our neighborhood.

• Powdery Mildew on Trees & Shrubs: Causes, Prevention, and Treatment
• Common Boxwood Pests That Could be Killing Your Shrubs
• What Are Those Spots on My Maple Leaves?
• Are Your Trees Being Destroyed by Gypsy Moth Caterpillars?
• Check for Signs of Hemlock Wooly Adelgid on Your Trees This Winter

Key Takeaways

• Beech leaf disease is a recent concern, first discovered in 2012. It has threatened the Hudson Valley since 2021.
• As of June 2024, we do not have a cure for beech leaf disease, though several treatment options have shown promising early results.
• Beech leaf disease is caused by microscopic nematodes that parasitically drain nutrients from leaves.
• Trees with beech leaf disease display dark bands on the leaves. As the disease progresses, the leaves look crinkled, deformed, leathery, copper, and shriveled.
• The best defense for your trees from BLD is reducing stressors that could affect their overall health. In limited testing, the fungicide Arbotect 20-S has shown positive results in reducing symptoms in infected beech trees.

The leaves of this beech tree are showing the black banding typical of beech leaf disease. Photo courtesy of Matthew Borden, Bartlett Tree Experts, Bugwood.org

Beech Leaf Disease in the Hudson Valley: The Basics

Symptoms of Beech Leaf Disease

Luckily, BLD has noticeable signs and symptoms indicating an infection. The lateral veins of beech leaves will have dark stripes or bands between them (these can be more easily seen by standing beneath the tree and looking

up at the leaves on a sunny day). Inspect your entire tree when looking for BLD, as the symptoms can be unevenly distributed throughout the canopy.

As the disease progresses, new symptoms appear, such as:

• Smaller leaves
• Leathery texture on leaves
• Heavier and more noticeable banding
• Aborted bud development (you’ll notice this during spring bud break)
• Crinkled, deformed, or shriveled leaves
• Copper-colored leaves
• Premature leaf drop
• Thinning canopy

How long does it take for beech leaf disease to kill a tree?

Typically, beech leaf disease will take up to five years to . For mature trees, it will depend on the size and overall health of the tree. However, most beech trees will likely die with several years of infection.

Where is beech leaf disease found in the Hudson Valley of New York?

The first recorded case of beech leaf disease was found in Ohio in 2012. The disease quickly spread across the northeastern portion of the country, eventually landing in New York in 2018 when arborists identified it in Chautauqua County.

The Hudson Valley was initially spared from the disease, but it ultimately spread to Orange and Dutchess counties in 2021 and Ulster County in 2023.

As of July 2024, New York counties that have had at least one confirmed case of BLD (though it is likely in other locations, just undetected) include:

Does beech leaf disease only affect American beech?

Attacks on American beech trees are especially worrying in New York, as the U.S. Forest Service estimates the American beech is one of the three most prominent trees making up our state’s forests.

The disease can also affect:

• European beech (F. Sylvatica)
• Oriental beech (F. orientalis)
• Chinese beech (F. engleriana)

The American beech is most vulnerable to BLD; the European, Oriental, and Chinese beech have shown more resistance to the disease.

Nematodes: The Cause of Beech Leaf Disease in the Hudson Valley

While we may still be learning about BLD, arborists have determined a specific nematode, Litylenchus crenatae ssp. Mccannii (Lcm), as the cause. The parasitic nematode sucks nutrients from beech leaves to survive and reproduce.

When does most damage occur to beech leaves?

The nematodes do most of their damage to leaves in summer and late fall.

As it gets later in fall, the nematodes exit the leaves and migrate to buds, where they overwinter and lay eggs for the next season.

How does BLD spread?

Lcm primarily spreads through a few methods, including:

• Wind and precipitation carrying nematodes to new, nearby trees (typically within 38 feet)
• Rainfall carrying Lcm to lower portions of the canopy
• Birds and beech blight aphids (Grylloprociphilus imbricator) carrying Lcm to new trees

A healthy American beech tree. Photo courtesy of Joseph OBrien, USDA Forest Service, Bugwood.org

Managing and Controlling Beech Leaf Disease

With BLD detected in every county in the Hudson Valley, it’s essential to know what you can do to help prevent the disease and treat it in your trees.

How to Prevent the Spread of Beech Leaf Disease

Since arborists are still studying BLD and its spread, our prevention options are currently limited. Once BLD establishes in an area, it cannot be eradicated. However, we still recommend a few cultural practices to protect your trees and the Hudson Valley’s forests as best we can.

Report Any Suspected Sightings of Beech Leaf Disease

If you suspect BLD in your yard or a nearby forest, the government of New York asks you to let them know so they can investigate further. You can email photos and information to the New York State Department of Environmental Conservation or submit a report through iMapInvasives.

Keep Your Trees Free of Stress in Summer

A healthy and unstressed tree is better able to fight against diseases. To help prevent tree stress, you can:

• Provide supplemental water for mature beech trees during droughts and heat waves. Newly planted beech trees benefit from supplemental water during normal conditions.
• Avoid mowing under a tree, as you will compact the soil and could damage the tree. · Have your beech trees professionally pruned to prevent branches from rubbing against each other or to remove dead and diseased branches.
• Apply a 2 to 3-inch layer of mulch around your tree. Keep it pulled away from the trunk, making sure the root collar (where the trunk flares out at the base) is fully visible.
• Fertilize your tree if a soil test indicates a nutrient deficiency (avoid high-nitrogen fertilizer in the summers!).
• Recent research suggests that soil or lower trunk application of phosphites may provide some level of BLD control by stimulating the tree’s natural defense response against environmental stressors, although results can vary considerably.

Avoid Moving Beech Trees and Logs

To combat the spread of invasive pests and infectious diseases, New York urges residents to avoid transporting firewood more than 50 miles from its origin source.

Additionally, avoid transplanting beech trees from areas with known infections to other locations, as this increases the risk of spreading BLD.

And, until there is a proven preventive or curative treatment for BLD, we advise against planting beech trees on your property.

A Promising Treatment to Reduce BLD Symptoms

READ THIS BEFORE TRYING ANY TREATMENT: As these methods are experimental, we do not have a full picture of how they affect trees, including long-term impacts on a tree’s health or its reaction with other species. Speak with an arborist about these treatment options.

Arborists began studying a new method for controlling BLD in 2022 by using the fungicide Arbotect 20-S. Typically used to treat Dutch elm disease and anthracnose in sycamore trees, Arbotect 20-S has shown promising results in treating symptoms of BLD.

Arborists injected infected trees with Arbotect 20-S and waited a year to test its effectiveness. The researchers found the trees showed reduced symptoms the next year compared to trees that had not been treated. The dormant buds in treated trees also showed fewer nematodes than non-treated control trees. Arbotect 20-S has a special label in New York designating it for use for combatting BLD. We recommend application after full leaf expansion and up to late July or early August.

THIS IS NOT A CURE FOR BLD. There is still no cure for beech leaf disease but regular injections of this fungicide every two years are expected to reduce symptoms and, hopefully, slow progression of the disease. If you have valuable beech trees on your property, it’s worth considering this treatment option.

Having an arborist inject an infected beech tree with Arbotect 20-S may reduce symptoms of BLD.

Call Hill Treekeepers to Protect Your Trees from Beech Leaf Disease

BLD is a potent threat that is killing beech trees throughout the Hudson Valley. Our understanding of the disease is still evolving; while there are no preventive treatments or cure currently available, we’re hopeful that researchers will develop better options in the near future. Until then, we must rely on early detection and removing diseased beech trees that are dead or dying.

If you’ve spotted BLD in the Hudson Valley, our team at Hill Treekeepers can help. We are updated with new treatment options and will do whatever we can to help your trees. Call us at 914-214-7045 or request a quote online to schedule an inspection for BLD and recommendations for treatment options.