Backyard Woods - ID tree health problems

Often the first visual clues of a tree health problem are symptoms like red needles, yellowing leaves, or wilting foliage. These problems may arise from a multitude of causal agents including insects, pathogens, other organisms, tree disorders, soil factors, weather events, pollution, and herbicide injury. The pattern of these symptoms on individual trees should be noted; for example, only old needles, only top of tree, only one side, or only inside the crown. Also, any pattern throughout your woods is important for identification. Are the affected trees randomly scattered, or in a group that is expanding? Are the affected trees in valleys or on ridge tops, or on the edge of a stand? Is only a certain size or age or species of tree affected?
Closer examination of the affected trees may reveal signs of the causal agent, such as the insect, fruiting body of the pathogen, a characteristic-shaped canker on a stem, insect tunnels under the bark, or a pattern of missing or discolored leaf tissue. Signs of the causal agent may be found on a different part of the tree than where the symptoms appeared. For example, red needles in the crown may be due to bark beetle attack on the lower trunk. Collection of these signs is invaluable in determining the causal agent; however, not all forest health problems will have readily identifiable causal agents; for example, herbicide injury, air pollution, girdling roots, root disease, and soil compaction. Other problems will have multiple signs from secondary insects and pathogens, and the actual causal agent may be missed. Some problems are the result of multiple factors. For example, oak decline is the result of a number of tree stresses (drought, root damage, gypsy moth defoliation, and early frosts) that weaken the tree. Then secondary insects (two-lined chestnut borer), or pathogens (armillaria root rot), or both may invade these weakened trees. Usually the dieback and decline progress slowly over several years.
Once you observe the symptoms and signs, consult reference materials to see if you can identify the causal agent. Forest insect and disease guidebooks and fact sheets may be available from your local library, county extension office, or State forestry office. Also, many web sites provide substantial information on forest pests. You may wish to contact the local Cooperative Extension Office for educational assistance and to inquire if a listing of qualified consulting foresters or arborists is available for your area. Otherwise, consult your phone book under "Arborists" or "Tree Service."
Introduced pests are a major threat to the health of your backyard woods. Introduced pathogens, such as chestnut blight, Dutch elm disease, white pine blister rust, and butternut canker, have dramatically and permanently altered forested ecosystems in the United States. Many introduced insects are impacting U.S. forests, including the gypsy moth, beech scale, hemlock woolly adelgid, Asian longhorned beetle, smaller European elm bark beetle, introduced basswood thrips, larch sawfly, and European pine shoot moth.