Beech mortality and drought in Maine

• Published in: Phytopathology Vol. 96; no. 6; p. S59
• Main Author: Kasson, M T
• Format: Journal Article
• Language: English
• Published: 01.06.2006
• Subjects: Cryptococcus fagisuga; Fagus grandifolia; USA, Maine
• ISSN: 0031-949X

FIA plots in Maine have shown a statewide increase in beech (Fagus grandifolia) mortality from 0.9% between 1982-95 to 3.3% between 1995-2003. In Aroostook County, inventory plots measured from 1999-2002 showed an average cumulative mortality of 13% since 1995. Plots measured from 2003-2004 showed an average cumulative mortality of 44% since 1995. Initial observations indicate two types of stands. The first type involves stands affected in the 1930's by beech bark disease (BBD), where a scale insect (Cryptococcus fagisuga) weakens trees so that a Neonectria fungus can kill the mature stems. Aftermath forests are now reaching a size and age at which beech bark disease probably contributes to the recent mortality. The second type of stand involves those in northern Maine that show significant mortality but no previous symptoms of BBD. The drought in 2001 and/or an outbreak of beech scale associated with warmer winters are thought to have predisposed these trees to infection and mortality due to the Neonectria fungus. Initial results indicate a continued increase in beech mortality where N. ditissima, N. faginata, and a potentially unknown Neonectria are involved in killing the trees, although their relative distribution varies across the state.