Field Guide to Diseases and Insect Pests of Idaho and Montana Forests

Hagle, S.K; S. Tunnock; K.E. Gibson; and C.J. Gilligan. 1987. Field Guide to Diseases and Insect Pests of Idaho and Montana Forests. U.S. Department of Agriculture, Forest Service. State and Private Forestry, Northern Region. Missoula, Montana. Reprint 1990. Publication Number R1-89-54.

Our thanks to Linda Hastie of Northern Region, State and Private Forestry, for content design and typesetting. We extend our appreciation to the following people for their technical review of the manuscript: Wayne E. Bousfield, James W. Byler, Jerald E. Dewey, Lionel D. Hall, Robert L. James, John H. Thompson, and Lawrence E. Stipe of USDA Forest Service, Northern Region, State and Private Forestry; R. Ladd Livingston and John W. Schwandt of Idaho Department of Lands; and Steven Kohler of Montana Department of State Lands. Numerous photographs were generously provided by Catherine A. Stewart of USDA Forest Service, Missoula Ranger District, Lolo National Forest; Mark D. McGregor of USDA Forest service, Northern Region, State and Private Forestry (retired); James Hoffman and Ralph E. Williams of USDA Forest Service, Intermountain Region, State and Private Forestry; J. W. Byler, J. E. Dewey, R. L. James, Steve Kohler, R. Ladd Livingston, and John W. Schwandt.

Introduction

Diseases and insect pests of conifer trees are important features of forests in Idaho and Montana. Many are capable of limiting timber production, creating tree hazards in recreation areas, reducing visual quality, and affecting wildlife use, fire hazard, or watershed properties.

To those unfamiliar with conifer diseases and insect pests, identifying the individual agents can be difficult and time consuming. There are more than 300 diseases and at least 1,000 insect pests common on conifer trees in Idaho and Montana. Of these, 45 diseases and 39 insects account for most of reported cases of damage. These 84 diseases and insects are our focus.

We discuss the most commonly encountered pests and biotic damages regardless of their potential for causing loss. Descriptions of pathogens, insects, and weather injuries focus on the most diagnostic features of each. Color photographs, line drawings and tables are used to illustrate and emphasize characteristics described in the text.

Subjects are arranged according to parts of trees typically damaged by the agent described. We begin with stems and roots, describing heartrots, cankers, bark beetles, root rots and various other agents which cause damage to stem or root tissues. Next we describe branch and terminal damagers. This includes such things as dwarf mistletoes, shoot boring insects, and branch cankers. The foliage damagers section is the most extensive with a variety of defoliating insects and needle casts described. Sections on some important seed and cone-damaging insects and common weather injuries conclude the pest descriptions.

A key is provided for separation of the biotic diseases and insect pests on the basis of their most diagnostic characteristics. The keys correspond to the various parts of trees affected. For example, if damage is found on needles the appropriate key is Key C--Foliage. All insect pests, diseases, and weather injuries described in the text are included in the keys. Where bark beetles which are commonly associated with root diseases are listed in the key, a note referring to the root disease section of the key is included.

In addition to the subject index, an index to damaging agents by tree species and part of tree affected is included. This provides a rapid means of assessing the number and variety of agents described for each tree species.

References listed by number at the end of each pest description will provide further information for both identification of pests and management of pest problems. The cited references should be readily accessible in USDA Forest Service Ranger District files and university libraries.

Deciding Where To Start In The Identification Keys

Description

Insects

Diseases

Field Guide to Diseases and Insect Pests of Idaho and Montana Forests

Contents

Contents

Abstract

Acknowledgements

Introduction

Deciding Where To Start In The Identification Keys

Description

Insects

Diseases

Other

References

Glossary

Index To Pests By Tree Species And Part Of Tree Affected

Technical Assistance Sources

Specimen Collection And Shipping