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Invasive Species: Beech Leaf Disease

Invasive Species: Beech Leaf Disease

Beech Leaf Disease

(Litylenchus crenatae and potential associates)
*Detected in Michigan*

WATCH LIST

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.

Striping between veins on beech leaves

Dark, thickened stripes between leaf veins are early signs. Photo courtesy of Jim Chatfield, OSU Extension.

Puckered beech leaves

Puckering, or raised areas between veins, may distort leaf shape. Photo courtesy of Jim Chatfield, OSU Extension.

Shriveled and distorted beech leaves

In late stages, beech leaf disease may cause extreme leaf distortion and curling. Photo courtesy of John Pogacnik, Ohio DNR.

Look-alike species: Several other pests and diseases are commonly mistaken for beech leaf disease. Please review these look-alikes before reporting possible beech leaf disease infestations.
  • 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

If you see beech trees affected by beech leaf disease, take one or more photos and make note of the location, date and time of the observation, and report to:

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, Delaware, Massachusetts, Maine, Maryland, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia and West Virginia. The disease is also present in areas of Ontario, Canada.

 

A map of beech leaf disease progression through the U.S., 2012-2021 

Michigan Distribution: Beech leaf disease has been detected in Hillsdale, Lenawee, Macomb, 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.

MORE INFORMATION:

Beech leaf disease pest alert - U.S. Forest Service