1) Trunk of an infected beech tree                  2) Perithecia

BEECH BARK DISEASE - This disease is caused by the fungus Nectria galligena, which is carried by two different scale insects, Cryptococcus fagisuga and Xylococculus betulae. It is transmitted into the tree when the insect feeds with its needle like mouthparts (beech scale link) The fungus kills the bark and cambium causing cankers which can eventually lead to the death of whole branches and the entire tree. Around October small red reproductive organs called perithicia can often be found making small circles on the bark of the infected tree. As of now there is no cure for this disease. Prevention of the beech scales is the only known method of control for beech bark disease.


This web site was created for the Morris Arboretum of the University of Pennsylvania's Plant Clinic.
Created by C. Hetzel and revised by S. Eisenman on 3/7/02.
URL = http://www.upenn.edu/PaFLORA/Plantclinic/beechbarkdisease.html