Friday, March 16, 2012

Backyard Woods - Tree health - treatment options

When you expect that pest epidemics may cause significant damage to your woods (based on your objectives), action to protect your backyard woods is warranted. Once you have identified the causal agent, then you can consider treatment options. Silvicultural (from "silviculture"—the science and art of producing and tending a woods) and biological treatments tend to be longer-term solutions and modify conditions that allowed the pest population to reach outbreak proportions, though the treatments may take months or years to effectively reduce the pest population. Physical and chemical treatments reduce pest numbers quickly, but do not modify the factors that led to the outbreak, thus pest populations are likely to rebound.
Silvicultural treatments
Silviculture is best used in the preventive measures described earlier. In outbreak situations, timely removal and destruction of infested trees can greatly reduce a pest population and keep other trees from being attacked. The remaining trees are more vigorous and less susceptible to further outbreaks.
Biological treatments
Biological treatments use the natural enemies (predators, parasites, and pathogens) that control pest populations. In your backyard woods, it is important to conserve and enhance these natural enemies, so the natural balance is not disrupted. Therefore, limit the use of broad-spectrum pesticides (insecticides, fungicides, and herbicides), promote a diverse flora (to provide a wide range of natural enemies and nectar sources for parasites), and ensure nesting sites for insect-feeding birds. Introduced species often become pests because they do not have natural enemies in their new environment. Importation and colonization of natural enemies from the native range of the pest has provided effective control, especially for many insect pests. Projects to introduce new biological control agents are conducted by Federal and State regulatory agencies. Once established, these natural enemies reproduce and disperse throughout the range of the introduced pest.
Physical treatments
Physical methods can be effective, particularly on the small scale of your backyard woods. For insects, various traps, barriers, and mass collecting have been successful. Insect traps generally use an attractant (a chemical scent, bait, light, or color) to lure the insect into the trap.
With enough traps, the pest population can be significantly reduced. Barriers on the trunks of trees can be effective for some caterpillars that migrate daily from the ground to the canopy to feed. Removal of insects by hand can be effective. For example when only a few host trees are present, gypsy moth can be controlled by placing a burlap band around the trunk of the host trees, then daily collecting and destroying the caterpillars that congregate under the burlap. For pathogens, removing and destroying the diseased tissue can be successful. For example, pruning the infected lower branches of white pines can reduce damage by white pine blister rust. Also, cutting barriers through root systems between infected and uninfected trees can stop the spread of oak wilt and Dutch elm disease.
Pruning the lower branches of white pines in zones with high incidence of white pine blister rust (Cronartium ribicola) can reduce damage from this introduced pathogen.
Chemical treatments
Pesticides can be useful in protecting valued trees from damage during pest outbreaks. There are many ways to apply pesticides—from root injections to aerial sprays. With any pesticide, follow the label directions and apply it only for the pests for which it is registered. Pesticides that specifically target the pest should be favored over broad-spectrum pesticides that may impact nontarget organisms. Also formulations and application methods that have minimal impacts on other organisms should be used. Opportunities to participate in cooperative treatment projects with other backyard woods owners and government agencies should be sought.

Forest pest management on private and public forests protects their economic, ecological, and social values. Through proper forest management practices, many potential pest problems are avoided. Forest health is promoted through practices that allow forests to recover quickly from natural or human-caused stresses and that provide for ecosystem stability. When serious pest problems are discovered, suitable treatments are applied to reduce the pest populations with minimal impacts on nontarget organisms. Through this holistic, ecological approach to forest management, the long-term productivity and health of the forested ecosystem is sustained.

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