Recently we received a beech leaf disease (BLD) update that was shared by Thomas Macy, Forest Health Program Manager with the Ohio Department of Natural Resources, Division of Forestry including a couple of maps. Additionally, background information has been added as part of this BYGL Alert to provide more information about BLD in case readers are not aware of this situation, or would like a background refresher.
Beech leaf disease (BLD) was first discovered affecting American beech trees in Lake County in northeastern Ohio in 2012. Currently, symptoms have been documented in 25 Ohio counties and parts of Connecticut, Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Virginia, West Virginia, and Ontario Canada.
Note that the regional map, shown below, was last updated in January 2023, and includes a color-coded key, by year, of BLD detections through 2022. The second map, specific to Ohio, does include spring 2023 discoveries in the Buckeye state. Both maps are a snapshot of confirmed detections at a designated point in time. If you suspect that you have observed a beech tree with BLD, it is important that you report what you are seeing and where you are seeing it. Information about reporting is included later in this BYGL Alert.
REGIONAL BLD MAP, January 2023
OHIO BLD MAP, Spring 2023
It has since been confirmed that the dark banding on leaves, leaf disfigurement, and branch dieback symptoms typical of BLD are linked to the presence of nematodes (microscopic worms) in the leaves and buds. American beech, European beech, and possibly other non-native species of beech are susceptible. In some areas, extensive mortality of understory beech seedlings and saplings has occurred.
Background Management Efforts
Work continues by multiple agencies and organizations to learn more about the damage BLD causes, how it spreads, and how it can be managed. These efforts are supported by detecting and reporting the occurrence of BLD in Ohio.
Detection and Reporting
Early symptoms of BLD include dark stripes or bands between lateral veins of leaves that are visible immediately upon bud break in the spring as shown in the photo below. Banding is most apparent when viewed from below, looking upward into the canopy. Affected leaves may be unevenly distributed in the lower canopy.
Other foliar symptoms include leaves that are crinkled and thickened giving them a leathery texture. Chlorotic banding may also appear; however, this symptom doesn’t always develop on trees suffering from BLD.
Finally, BLD may appear on whole trees as aborted bud development and premature leaf drop resulting in a thinning of canopy cover over time. Tree mortality of all age classes has been observed occasionally within 2 to 7 years but appears more common with smaller trees as shown below. This can significantly affect forest regeneration with the percentage of American beech dramatically declining in forest stands.
Monitoring and Reporting
If you suspect you are seeing BLD, please contact your local county Extension office (https://extension.osu.edu/lao#county), or a service forester or urban forester with the Ohio Department of Natural Resources, Division of Forestry (https://ohiodnr.gov/discover-and-learn/safety-conservation/about-ODNR/forestry).
You can also report symptoms using the Tree Health Survey, which can be accessed by visiting https://treehealthapp This app trains users how to identify beech trees and beech leaf disease symptoms. You can use Tree Health Survey to record the location and symptom severity of diseased trees as well as submit photos.