Beech leaf disease (BLD) was first discovered in North America in 2012 in Ohio. While the cause of the disease has yet to be determined, BLD has spread quickly and is now found in several of the United States and Ontario. It behaves much like an invasive, alien forest pest. The disease seems to currently be in a rapid expansion phase similar to what has been seen with other invasives, such as the emerald ash borer. From 2012-16, BLD spread across 1250 acres per year in one Ohio county (Ohio State University, 2019). In many of the areas that have been infected with BLD, there are already visible changes in the canopy.
Photo: Ohio State University, USDA Forest Service, Bugwood.org