Emerging Pest Alert

Beech bark disease continues to spread in Michigan

Scientific Name: Nectria coccinea var. faginata

Describer: Lohman, Watson, and Ayers

Common Name: Beech bark disease

Title: Beech bark disease continues to spread in Michigan


Significance: Beech bark disease (BBD) arrived in North America in 1890 through the movement of ornamental trees shipped from Europe to Nova Scotia. Over the next century, the disease moved across eastern Canada and south to New England, New York, Pennsylvania and West Virginia. Spot infestations have appeared as far south as North Carolina and Tennessee. The disease was discovered in Michigan in 2000; however, its importance has been overshadowed by other forest pest introductions in that area. Currently, beech bark disease is spreading in Seney National Wildlife Refuge in Michigan, where scientists expect the disease to eventually kill most of the state's beeches. 

Once established, BBD can kill 75 to 80 percent of the beech trees in a given area. The life cycle includes two stages. It begins with the beech scale insect, Cryptococcus fagisuga,that feeds on the beech tree’s thin bark, making the tree vulnerable to infection by the Nectria fungus (either Nectria coccinea var. faginata or Nectria galligena). This infection kills tissue and often entire trees. Many times other insects and wood-rotting fungi can quickly invade the wood beneath bark killed by beech bark disease and compound the problem. Trunks weakened by BBD are also susceptible to damage by heavy winds, which may them to break in half--a condition called “beech snap.”

Pathways: The beech scale insects can be spread by movement of infested firewood or by wind, birds or other animals that brush against infested trees. Fungal spores are wind dispersed.

Hosts: Fagus grandifolia (Ehrh.), beech tree

Distribution: In North America BBD is present in Southeastern Canada, New England and has been reported as far south as North Carolina and Tennessee. 


13 January 2007. Beech bark disease joins list of Michigan eco-invaders. Wood TV8. http://www.woodtv.com/Global/story.asp?S=5934597&nav=0Rce  

United States Forest Service - Beech bark disease site: http://www.na.fs.fed.us/fhp/bbd/  

Seney National Wildlife Refuge-Where the fungus is spreading in Michigan: http://www.fws.gov/Midwest/Seney/  

McCullough, D.G., Heyd, R., and J.G. O’Brien. 2000. Michigan State University Extension Beech Bark Disease Alert: Biology and Management of Beech Bark Disease Michigan’s Newest Exotic Forest Pest. Michigan State University Extension and Michigan Society of American Foresters. http://michigansaf.org/ForestInfo/Health/BBdisease.htm