Identify and Manage Dutch Elm Disease

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Author
Linda Haugen is a Plant Pathologist with the USDA Forest Service, Northeastern Area State and Private Forestry, St. Paul, Minnesota.
Acknowledgments
Thanks are extended to the many scientists who contributed suggestions and background material for this publication. Particular thanks for review of technical content go to: Mark Stennes, Consulting arborist, Top Notch Tree Care; Dr. Jay Stipes, Professor of Plant Pathology, Virginia Polytechnic Institute and State University; Dr. Eugene Smalley, Emeritus Professor of Plant Pathology, University of Wisconsin-Madison; Dr. Alden Townsend, Research Geneticist, USDA National Arboretum; James Sherald, Plant Pathologist, National Park Service; and Dr. Richard Campana, Emeritus Professor of Plant Pathology, University of Maine. Thanks for review of practical content are extended to Jim Hermann of Minneapolis Park and Recreation Board for review of the manuscript.

Cover photo: Branch flagging symptoms from a single point of Dutch elm disease infection in crown of elm. (Photo courtesy of Dr. R. Jay Stipes.)

The use of trade of firm names in this publication is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service.

Contents

Introduction
Symptoms
Distinguishing Dutch Elm Disease
from other problems
Disease Cycle of Dutch Elm Disease
Managing Dutch Elm Disease
Trees in Natural Stands and Wild Areas
Deciding Which Management Practices to Use
Bibliography
Introduction

At one time, the American elm was considered to be an ideal street tree because it was graceful, long-lived, fast growing, and tolerant of compacted soils and air pollution. Then Dutch elm disease (DED) was introduced and began devastating the elm population. Estimates of DED losses of elm in communities and woodlands across the U.S. are staggering (figure 1). Because elm is so well-suited to urban environments, it continues to be a valued component of the urban forest despite the losses from DED. The challenge before us is to reduce the loss of remaining elms and to choose suitable replacement trees for the ones we cannot save.