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Invasive Species: Beech Leaf Disease
Beech Leaf Disease
(Litylenchus crenatae and potential associates)
*Detected in Michigan*
WHAT TO LOOK FOR
- Striping - bands of thickened, dark green tissue between the leaf veins.
- Distorted, puckered or curled leaves.
- Leaf symptoms that are visible from leaf out until fall, best seen by looking up into the canopy.
- Some branches may be affected while others are not.
- Reduced leaf and bud production and possible leaf loss as disease progresses.
Dark, thickened stripes between leaf veins are early signs. Photo courtesy of Jim Chatfield, OSU Extension.
Puckering, or raised areas between veins, may distort leaf shape. Photo courtesy of Jim Chatfield, OSU Extension.
In late stages, beech leaf disease may cause extreme leaf distortion and curling. Photo courtesy of John Pogacnik, Ohio DNR.
- Beech leaf curl aphid, causes puckering and curling at the leaf margin with aphids or their cast skins usually visible inside the curled areas of the leaf, but usually isn’t harmful to tree health.
- Erineum patch, caused by eriophyid mites, creates light green or yellowish to orange patches on the upper side of the leaf, rarely affecting overall tree health.
- Anthracnose creates small brown or black spots on leaves that eventually cause dead areas. New leaves may curl. Fungi infect leaves and stems and are most active in wet spring seasons, with a limited impact on tree health.
- Powdery mildew, affecting many trees and shrubs, causes beech leaves to turn yellow. It may cause defoliation but won’t kill beech trees.
REPORT BEECH LEAF DISEASE
ABOUT THIS SPECIES
The nematode (microscopic worm) Litylenchus crenatae has been identified in trees with beech leaf disease, but it is still unknown whether symptoms are caused by the nematode alone.
Habitat: Beech leaf disease affects American beech, Fagus grandifolia, which is native to Michigan. The disease can also affect European and Asian beech varieties that have been introduced as landscape species.
Native Range: Further research is needed to determine the origin and cause of beech leaf disease.
U.S. Distribution: First identified in Ohio in 2012, beech leaf disease has now been documented in areas of Connecticut, Massachusetts, Maine, Michigan, New Jersey, New York, Pennsylvania, Rhode Island, Virginia and Ontario.
Michigan Distribution: Beech leaf disease has been detected in Lenawee, Oakland, St. Clair, Washtenaw and Wayne counties in Michigan.
Michigan Status: Beech leaf disease is on Michigan’s watch list.
Local Concern: After several years of infection, indicated by progressive curling and distortion of foliage and a sparse canopy, beech leaf disease can kill beech trees. Young trees seem to be more susceptible to mortality than mature trees. Michigan’s 37 million beech trees, important in the forest ecosystem, are already being lost to beech bark disease. If established, beech leaf disease can spread across the landscape, causing damage and additional loss to this important forest resource.
Means of Introduction or Spread: At this time, beech leaf disease spread is not well understood. It is possible the disease could be moved long distances on nursery stock or other beech material containing leaves and buds. Since it may take a few years for symptoms to show, by the time it is identified in a location it could be well established and impossible to eradicate.
Control: Although research is ongoing, little is known about the origin or biology of beech leaf disease, and no effective control or eradication measures have been developed. Management should focus on preventing its introduction by restricting movement of beech materials from areas known to have the disease, conducting beech tree inventories to identify resources at risk and monitoring trees closely for signs and symptoms. In landscapes and forests, opportunities should be taken to increase the diversity of tree species and implement best management practices to keep trees healthy.
Beech leaf disease pest alert - U.S. Forest Service