Breaking Down Beech Leaf Disease By Dane Buell Dane Buell is the past chairman of the ANSI A300 committee and TCIA representative. With over 30 years of experience, Buell holds several leadership roles in the tree care industry.
In recent years, Beech Leaf Disease (BLD) has emerged as a significant threat, caus- ing alarming tree mortality rates across the Midwest, Northern Mid-Atlantic, and Northeastern states. This condi- tion primarily targets American beech, European beech, and other non-native beech species, resulting in dark striping on leaves, leaf distortion, and ultimately death if untreated. With its rapid spread and management challenges, I sought in- sights from leading industry experts Mat- thew Borden, DPM, Research Scientist at Bartlett Tree Research Laboratories, and Rich Cartier, Northeast Territory Manag- er at Rainbow Ecoscience. BACKGROUND ON BEECH LEAF DISEASE What causes BLD? Beech Leaf Disease is caused by the foliar nematode Litylenchus crenatae . Intrigued by the term “disease,” I asked Borden why we describe BLD as such, given that
pathogens (fungi, bacteria, viruses) typi- cally define disease in arboriculture. “Nematodes and disease pathogens are often combined from a research and scientific perspective due to the ongoing stress they cause in affected plants, Borden explained. However, in this instance, the causal agent of BLD was identified after the condition was named, making its name ironically ac- curate but somewhat confusing.” As an experienced practicing arborist, I had never heard of a foliar nematode before. Both Cartier and Borden con- firmed that similar tree pest problems are known in our industry. For instance, foliar nematodes in the Aphelenchoides group attack many popular landscape perennials. Pine Wilt Disease, caused by the pine wood nematode Bursaphel- enchus xylophilus , is another tree-kill- ing nematode that affects non-native pine trees, but outbreaks are reported- ly easier to get under control.
Where did BLD originate? The origins of BLD trace back to Japan. Recently, a team of U.S. researchers visited Japan to understand why beech trees there seem less affected. Borden
Foliar nematode Litylenchus crenatae, the cause of Beech Leaf Disease.
ArborTIMES ™ Spring 2025 | 45
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