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Beach leaf disease was first observed in Ohio in 2012. It's means of introduction is unknown, although it may have arrived in North America through the transport of wood with an invertebrate vector. It causes a disease of beech trees that disfigures leaves and can lead to tree mortality. 

A chance discovery in an Ohio woodland has turned into a multi-disciplinary, multi-agency, and multi-national effort to piece together a puzzle and understand a scourge that is killing trees by the thousands in northern states east of the Great Plains. The leaves of young beech trees are failing somehow. Scientists have figured out what causes the malady; it’s the 'how' that has them scratching their heads. Beech trees are one of the most common trees in America's northern and northeastern forests. Their nut crop feeds birds and other animals, and its wood is prized for bentwood furniture. The symptoms of beech leaf disease were plain to see – sunken dark spots on the leaves, which eventually died – but opinions differed on the cause. Was it bacterial, fungal, or viral? Then, a plant pathologist working for the State of Ohio noticed wiggly things in the leaf lesions. They turned out to be nematodes, microscopic worms that live in the soil, that had somehow managed to make it to the tree canopy 40-50 feet above ground. Nematode samples were sent to Beltsville, MD, for analysis and identification at the Agricultural Research Service (ARS) Mycology and Nematology Genetic Diversity and Biology Laboratory in Beltsville, MD. The nematode, Litylenchus crenatae, turned out to be native to Japan – the first population of L. crenatae found in the Western Hemisphere. The curious thing is that it's not a tree-killer in Japan.