Beech leaf disease (BLD) affects and kills both native and ornamental beech tree species. It is associated with a nematode, Litylenchus crenatae mccannii. This disease has only been discovered in recent years and much about it, including the full cause and how it spreads, is still unknown. Because of this, DEC is collecting information on symptomatic beech across New York State in the hopes of learning more about the disease.
Disease Symptoms
Symptoms of BLD include:
- Leaf striping, curling, and/or leathery texture.
- These symptoms are most easily noticed by looking up into the forest canopy and may be visible from leaf out in May until leaves fall off in October
- In early infestations, only a few leaves may be affected. Eventually, affected leaves wither, dry, and yellow.
- Reduced leaf and bud production.
- Leaf loss has been recorded only in heavily affected trees, but would be noticeable in summer months.
- A single tree can contain both heavily infected and unaffected branches.
Environmental Impacts
Beech leaf disease can kill beech trees of all ages though younger trees appear to die more quickly.
In New York State where our predominant forest type is beech/birch/maple, beech is one of the most common forest species. Beech is particularly valued in the forest for hosting nesting sites and providing nuts for birds, black bears, and other wildlife.
Look-alikes and Other Beech Phenomena
Review the table below for other issues you may see on beech trees. It is possible for a beech tree to exhibit symptoms of both beech leaf disease and any of these other impacts simultaneously.
DEC is interested in reports of leaf striping or curling associated with BLD on any beech tree, but we do not manage the other issues listed in the table.
| Name | Example | Signs and Symptoms | About |
|---|---|---|---|
| Beech bark disease (BBD) |
| Symptoms: The symptoms of this disease are concentrated on the bark. A white, fuzzy coating on the tree's trunk and branches is a sign of the scale insect.
| Beech bark disease is the result of the combined effects of a non-native scale insect and a canker fungi. The insect pierces and sucks at the tree, allowing the fungus to enter and cause harm internally. This disease is common across New York State and is not managed by DEC. Most trees die within 10 years of infestation by the insect and fungi. |
| Erineum patch |
| Symptoms: Yellowish patches appear on the upper side of the leaf. The patches are light green in spring, then fade to orange and eventually brown.
| Erineum patch is caused by eriophyid mites and is not typically viewed as a problem. The patches rarely cover enough of the leaf to affect the overall health of the tree. |
| Powdery mildew |
| Symptoms: Leaves and stems appear to be covered in a white, powdery substance that resembles powdered sugar.
| Powdery mildew is caused by native fungi and affects a variety of shrubs and trees. This is a cosmetic disease that does not kill the tree but could cause defoliation if not addressed. |
| Anthracnose |
| Symptoms: Small brown or black spots on leaves that eventually cause dead areas. New leaves may curl.
| Anthracnose affects a variety of tree species and is caused by a group of fungi. In beech, the fungi infect the leaves and stems and can cause dieback or some defoliation. The disease thrives in years where there are cool, wet conditions during bud break. |
| Beech blight aphid |
| Signs: These native insects have a fluffy, white outer coating. Also known as "boogie woogie aphids", the insects will shake or "dance" when the branch is disturbed in order to ward off potential predators.
| This insect is native and feeds on beech without causing much harm. |
| Beech leaf rolling aphid |
| Signs: Leaves may curl and appear yellow/faded between the veins.
| These injuries are caused by aphids feeding on the leaves. This insect is native and feeds on beech without causing much harm. |
| Marcescense |
| Signs: Beech retain their dead leaves through the winter.
| This is a totally normal, common, and harmless feature of beech. |
Distribution and Habitat
BLD was first discovered in Ohio in 2012 and has since spread to Pennsylvania, New Jersey, Connecticut, Maine, Massachusetts, Rhode Island, and Ontario, Canada. BLD was first observed in New York in 2018 in Chautauqua County and was found in Suffolk and Nassau counties in 2019. It has since spread throughout western, central, and southern NY.
We suspect there are infestations elsewhere in the state that we have not yet found, and tracking locations of this disease will help us learn more about its biology.
Management
DEC's Forest Health team is surveying trees across the state to:
- identify infested stands
- monitor the disease severity and progression
DEC has partnered with other affected states to conduct research and share findings on beech leaf disease.
Currently, there is no known way to control or manage this disease.
How You Can Help
After reviewing the identification materials on this website, if you think you have seen signs of BLD:
- Report BLD
- View DEC's BLD flyer about disease symptoms and how to report (PDF).
- Take photos of symptoms, as well as the tree's leaves, bark, and the entire tree if possible. Photos of leaves held up to the light, or taken through the canopy, make it easier to identify BLD symptoms.
- Submit a report through iMapInvasives. BLD is listed as the nematode Litylenchus crenatae maccannii.
- Follow the NYS firewood regulation, which limits firewood movement to no more than 50 miles, to help prevent the spread of all pests and diseases that threatened our forests. Additionally, if BLD symptoms are observed in an area, avoid moving firewood from that location.
If you have questions about your trees, email photos and location information to [email protected]. Or you may contact the Forest Health Diagnostic Lab via phone at 1-866-640-0652.
Please note that because the BLD is well documented on Suffolk and Nassau Counties, it is no longer necessary to report the disease on Long Island.
Additional Resources
- BLD information from Forest Invasives Canada
- BLD fact sheet from the Connecticut Agricultural Experiment Station (PDF) (shared with permission from source)