The Maryland Department of Agriculture confirmed worsening symptoms of beech leaf disease in multiple counties, including Allegany, Anne Arundel, Baltimore, Caroline, Carroll, Cecil, Charles, Frederick, Harford, Howard, Montgomery, Washington, and Baltimore City. Caused by the nematode Litylenchus crenatae maccannii, a microscopic wormlike organism that inhabits the leaves and buds of beech trees, the disease affects all beech species, including the native American beech (Fagus grandifolia). The disease has also been detected in neighboring states, including Pennsylvania, Virginia, West Virginia, Delaware, New Jersey, Ohio, Michigan, New York, Connecticut, Massachusetts, Rhode Island, New Hampshire, Vermont, and Maine.
Beech leaf disease poses a significant threat to both native and ornamental beech trees, leading to tree mortality. The nematode damages tree buds during winter by consuming internal tissues, causing symptoms such as leaf striping, curling, a leathery texture, and reduced leaf and bud production. These symptoms are most visible on the underside of leaves and can appear year-round. Young trees may die within one year of infection, while mature trees typically succumb within six to ten years.
No preventive measures are currently available to stop nematode infection. However, certain treatments show promise. Pruning trees in winter or early spring can improve light and air circulation, helping to dry leaves and hinder nematode survival. Applying fluopyram in late summer, when nematodes move from leaves to buds for overwintering, has been shown to kill over 90% of live nematodes, particularly when leaves are wet. For smaller trees, PolyPhosphite30 fertilizer, applied as a soil drench or injection during the growing season, can stimulate the tree’s immune system. Landowners seeking treatment options can contact licensed pesticide applicators listed at https://www.egov.maryland.gov/MDA/Pesticides. Additional treatment details are available at https://web.uri.edu/coopext/wp-content/uploads/sites/2042/2024-BLD-update_9.23.24-1.pdf.
The Maryland Department of Agriculture’s Forest Pest Management team continues to monitor the spread of beech leaf disease. Surveys are underway to detect the disease and nematode in additional counties, with permanent survey plots established across the state since 2019. Residents are encouraged to report symptoms using the Tree Health Survey app https://treehealthapp or by emailing fpm.mda@maryland.gov.
Beech leaf disease threatens Maryland’s forests and urban landscapes, where American beech trees are valued for their ecological and aesthetic contributions. The rapid progression of the disease in young trees underscores the urgency of early detection and management. While treatments like fluopyram and PolyPhosphite30 offer some control, their application requires professional expertise and precise timing. The ongoing surveys aim to map the disease’s spread and inform future management strategies.
The disease’s presence in 14 surrounding states highlights its regional impact, with Maryland’s proactive monitoring efforts aligning with broader initiatives to protect beech populations. Landowners and residents play a critical role in reporting symptoms to aid these efforts. As the disease continues to spread, the Maryland Department of Agriculture emphasizes the importance of community engagement and professional intervention to mitigate its impact on the state’s beech trees.