Plant Health Program, Doctor of


Document Type

Doctoral Document

Date of this Version

Fall 12-19-2014


Borman, C. J., 2014. Managing Threats to the Urban Forest: from Dutch Elm Disease to Emerald Ash Borer - Learning from Experience. Doctoral Document. Doctor of Plant Health, University of Nebraska - Lincoln.


A Doctoral Document Presented to the Faculty of The College of Agricultural Sciences and Natural Resources In Partial Fulfillment of Requirements For the Degree of Doctor of Plant Health, Major: Doctor of Plant Health, Under the Supervision of Professor Gary L. Hein. Lincoln, Nebraska: December 2014

Copyright (c) 2014 Christopher John Borman


The urban forest provides important essential services to all municipalities; however, its value is often overlooked. The urban forest contributes to energy savings, environmental benefits, psychological well-being, and social benefits. Managing the urban forest in a sustainable manner is important if we wish to benefit from these services well into the future. Reliable management techniques have been created through previous experiences with pests, and these should be utilized and improved for use on urban forests.

American elm (Ulmus americana L.) was once a major component of the urban forests of North America. In 1927, Dutch elm disease (DED) was introduced to the U.S. state of Ohio, and within 60 years the disease had decimated most of the American elm population of North America. This had a dramatic effect on communities largely planted with elms. Management techniques need to disrupt the disease cycle. Control can be achieved through persistent integrated practice. Some of the tools and techniques used for DED management can also be used in fighting a relatively new introduced invasive species, emerald ash borer (EAB) (Agrilus planipennis). Ash trees are currently a major component of the urban forest, and EAB poses a very similar threat that DED had in the past. By learning from our experiences, we may be able to slow the mortality rate of ash trees and utilize our resources in a sustainable manner.

Large-scale management of urban forest pests is important, and one technique that aids in managing diseases is tool sanitation. Contaminated tools have been documented transferring fungal and bacterial diseases to healthy trees. A preliminary study is presented that tests the efficacy of 70% isopropyl alcohol, 10% bleach, Lysol®, and ShockWave Green24® when used for tool sanitation. Results suggested that all chemicals are suitable for eliminating the fungi Ophiostoma sp., but some provided poor control of other unidentified fungi. The experiment showed the value of sanitation in the field in the prevention of spreading disease.

Advisor: Gary L. Hein