THE WASHINGTON INSTITUTE OF DENDROLOGY RESEARCH

Departments

Useful Forestry and Tree Pathology Links

Trees are subject to attack by a variety of pathogens or diseases. These diseases are usually caused by fungus or bacteria, but can also be caused by viruses and other organisms. In many cases when a tree has a disease, there are many other factors that have contributed to stress the tree, and allow the disease organism to enter and spread within the tree. These factors may include soil disturbances or compaction, physical damage to part of the tree, local conditions (especially excessive or not enough moisture), and the presence of innoculum in the area. Forest tree diseases may only affect the appearance of trees or they may cause deformities, reduce growth, weaken the tree allowing attacks by insects and other diseases, or even cause the death of individual trees or in rare cases entire sections a forest.

Noninfectious tree diseases are those caused by nonliving agents. This type of disease is not transmitted from one plant to another. Extremes in temperature and water supply are the most common causes of this type of disease. Other causes are chemical substances in the soil, water, and air, transplant shock, and mechanical injuries. These nonliving disease agents are a major cause of loss in forest and landscape trees. Often they weaken the tree, enabling living agents such as fungi, bacteria, viruses, nematodes, and insects to attack and further injure or kill the tree. These living agents may build up on trees weakened by noninfectious agents and threaten the health of nearby trees. Superficially, the symptoms of noninfectious diseases may resemble those produced by insects or fungi. If no signs of these organisms are present, the tree may have been affected by one of the agents described here. Even if signs of fungi or insects are present, a nonliving agent may be the underlying cause of your tree's problems. In most cases, prevention is the key to minimizing injury.

Good cultural practices and tree care is essential in keeping a tree vigorous and healthy. Like humans or livestock, vigorous trees are more likely to fend off diseases than are weakened or stressed trees.

Tree Pathology Links

Tree Identification Links

  • Chestnut Trees
    This website will help you to identify and distinguish among several species of the chestnut tree family (Castanea ) commonly seen in North America. Identify five Chestnut trees by comparing leaves, twigs, buds, and nuts.
  • Chestnut Trees
    This website will help you to identify and distinguish among several species of the chestnut tree family (Castanea ) commonly seen in North America. Identify five Chestnut trees by comparing leaves, twigs, buds, and nuts.
  • Identifying Trees
    This website explains tree identification and provides many web links for tree indentification and uses for wood.
  • Tree Encyclopedia
    Explore over 3500 pictures of more than 450 tree species with large diagnostic photos, detailed botanical and landscape information.
  • Tree Guide
    This website provides information on identifying coneferous trees, deciduous trees, and other tree information.

Forestry & Other Associations

Forestry Groups and Wilderness Organizations

  • North Cascade Conservation Council
    "To protect and preserve the North Cascades' scenic, scientific, recreational, educational, and wilderness values."
  • Save The Redwoods League
    Since 1918, Save the Redwoods League has saved ancient redwood forests and redwood ecosystems to ensure that current and future generations can feel the awe and peace that these precious natural wonders inspire.
  • Washington Native Plant Society
    Conservation and advocacy make the Washington Native Plant Society the voice for native plants.
  • Spirit Bear Youth Coalition
    Worked to set aside 2500 square miles of Princess Royal Island B.C. Canada for a Kermode Bear safe home.
  • The Mountaineers
    An excellent mountaineering and outdoor group based in Seattle, Washington.
  • Pacific Northwest Hikes
    Hike descriptions, weather info and useful items
  • Animated Knots by Grog
    Great site for learning about knots with excellent visuals.
  • Tying The Knot
    This guide, with excellent visuals, explains how to tie 30 popular and useful knots.

Forest & Forestry Books

The following books are available through Luebeck Haus Bookstore.

An Outstanding Dendrology and Horticulture Book