Beech bark disease

Beech bark disease is a complex disease resulting from the interaction of a sap-sucking insect, known as beech scale or Crytococcus fagisuga, and two species of fungi, Nectria coccinea var. faginata and Nectria galligena. Beech scales themselves do not threaten the health of beech trees, but the insects feed on the sap in the inner bark of the tree leaving exposed areas, making the tree susceptible to Nectria colonisation which causes their decline. Mortality occurs within 3-6 years after scales infest the area. Up to 95 percent of beech trees in a given area can succumb to beech bark disease once initial infection occurs.