Beech leaf disease (BLD) is an emerging disease caused by a nematode, or microscopic worm. All cultivars of American and European beech are susceptible. BLD was first observed near Cleveland, Ohio, in 2012. Since its initial detection, the disease has been observed in 15 additional states from North Carolina to Maine, and in Ontario, Canada. BLD is caused by a foliar-feeding nematode, Litylenchus crenatae mccannii, a subspecies of a recently described nematode infecting Japanese beech in Japan, where it causes a mild disease. In the United States, however, beech infected with this nematode have been observed dying as early as six years from the onset of symptoms.
Symptoms
Early symptoms of BLD include distinct striping along the leaf veins and darkening and/or chlorosis of the infested area. From the top of the leaves, the discoloration along veins often appears cupped or puckered. Symptoms typically progress from the bottom of the canopy upward, but may also appear randomly scattered throughout the canopy. Symptoms can be confused with leaf galls caused by erineum mites or damage caused by aphids that feed on beech.
After successive years of infestation, leaves become deformed and have a thickened, almost leathery texture. By this stage the photosynthetic function is severely reduced, and trees cannot produce the carbohydrates needed for overwintering and vigorous growth. This weakens the tree and predisposes it to other secondary stresses. Severe nematode damage within buds contributes to the tree aborting leaf buds, and twig dieback can follow. Recently, published research has demonstrated effective treatment of BLD via root flare infusion, or with another a product applied to beech trees in summer before and during the nematode dispersal period. Arrange an appointment with your local Bartlett Arborist Representative today to have your beech trees examined and tested for this disease.
