Judy Gibbs, urban forestry specialist for the city of Duluth, tapes a sign requesting that people not disturb the ash tree at Chester Bowl that was girdled (top right) in an experiment to attract the emerald ash borer. The tree will serve as a barometer to determine if and when the pest strikes. Girdling induces stress, which changes the tree’s chemistry, something ash borers can sense. (Bob King / rking@duluthnews.com)
Read the article: Arbor Day celebrates trees with new invaders in mind
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