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Tree insects and diseases are natural ingredients of a healthy forest ecosystem, helping to recycle nutrients, build soil and make room for new growth. Insects and diseases are agents of diversity across the landscape. They bring about change by creating openings for new growth, as do fire, wind and flooding. Bugs and pathogens provide food and homes for cavity nesting birds, prey species like squirrels, and many other wildlife species.
In the Swan Valley, most of the insects and diseases at work in the forest are natives (white pine blister rust, introduced from Europe, is an exception). Our trees are generally resistant to bugs and pathogens unless they have been weakened due to old age or from stresses such as drought, competition and injury. When trees are stressed they can emit a chemical odor that attracts insects.
Despite their beneficial effects, tree insects and diseases can cause problems for forest managers and property owners by limiting timber productivity, creating hazards, and spoiling aesthetics. This handbook addresses the most common insects and diseases likely to kill trees in the Swan Valley.
For a more thorough look at insects and diseases in our area, get a copy of the field guide, Diseases and Insect Pests of Northern & Central Rocky Mountain Conifers, published by the USDA, Forest Service Northern and Intermountain Regions. Also visit the following websites:
www.dnrc.mt.gov/forestry/assistance/pests/
www.fs.fed.us/r1-r4/spf/fhp/mgt_guide/index.htm |
