Date of Award

8-5-2019

Semester of Degree

December

Document Type

Open Access Thesis

Degree Name

M.S. in Environmental and Forest Biology

Department

Environmental and Forest Biology

Major Professor

Stephen Teale

Steering Committee Member

John Drake

Steering Committee Member

Thomas Horton

Abstract

Beech Bark Disease (BBD) is a serious invasive complex composed of native and introduced organisms affecting American beech in the northeastern United States and eastern Canada. BBD develops first with the invasion of the scale insect Cryptococcus fagisuga (Advance Front), then with attack by ascomycetous fungi in the genus Neonectria (Killing Front), and finally with chronic infection and excessive production of beech root sprouts (Aftermath Forest). Recent evidence suggests that disease development in the Aftermath Forest is influenced by host bark chemistry including phosphorous, nitrogen, and the flavanols catechin and isorhamnetin. This study examined the concentrations of these four compounds in the bark of American beech along five transects in New York and Pennsylvania. These transects extended from the Pre-BBD Forest to the Aftermath Forest, passing through the Advance Front and Killing Front. Nitrogen and phosphorous did not vary with disease initiation or progression, but catechin was elevated significantly on Killing Front trees with active Neonectria infection. Isorhamnetin was not detected in any of the study trees. This study is the first comparison of tree chemistry across all phases of BBD and is the first to highlight an induced defense response of the host to challenge by the pathogen.

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