A Technical Report from The Bartlett Tree Research Laboratories
Beech leaf disease (BLD) is an emerging disease caused by a nematode, or microscopic worm. All cultivars of American and European beech are susceptible. Beech are ecologically important trees in the eastern United States and are common feature trees in landscapes. Beech leaf disease was first observed in Lake County, Ohio (Cleveland area) in 2012. Since its initial detection, the disease has been observed in other counties in Ohio, Pennsylvania, New York, Connecticut, and Ontario. BLD is caused by a foliar-feeding nematode, Litylenchus crenatae, which was described initially on Japanese beech in Japan where it causes a mild disease. In the United States, however, healthy beech trees have been observed dying in a period of six years from the onset of symptoms. As BLD progressively worsens, the tree’s overall health weakens exposing it to secondary insect pests and diseases.