. Insekten und Pflanzenkrankheiten Bedingungen in den Vereinigten Staaten, 1979-83: Was wächst in unseren Wäldern?. Wald Insekten United States; Bäume Krankheiten und Schädlinge United States; Pflanzen Krankheiten und Schädlingen Widerstand. Die Notwendigkeit zur Behandlung von Douglas-fir tussock Motte Ausbrüche müssen bestimmt werden durch den Vergleich der gesamten Auswirkungen eines unkontrollierten Ausbruch mit den Ressourcen, die gespeichert werden würde, wenn der Ausbruch behandelt wurden. Wenn Populationen gesteuert werden, mehrere Arten von Maßnahmen werden häufig verwendet, z. B. eine Kombination aus Flor - ticide Behandlung und waldbauliche Behandlung. Insektizid. Vielen insectici

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. Insect and disease conditions in the United States, 1979-83 : what else is growing in our forests?. Forest insects United States; Trees Diseases and pests United States; Plants Disease and pest resistance. The need to treat Douglas-fir tussock moth outbreaks must be determined by comparing the total impact of an uncontrolled outbreak with the resources that would be saved if the outbreak were treated. When populations are controlled, several types of measures are commonly used, such as a combination of insec- ticide treatment and silvicultural treatment. Insecticide Treatment. Many insecticides have been tested, and rejected, for direct control of the tussock moth. Only two chemi- cals, acephate and carbaryl, are currently registered for aerial ap- plication against the Douglas-fir tussock moth in forest stands. Other chemicals are registered for moth control on ornamental trees. Biological agents have also been approved for use against the tussock moth. The bacterium Bacillus thuringiensis can be ap- plied both from the air to forest stands and from the ground to or- namental trees. A laboratory- cultured nuclear polyhedrosis virus is also approved for control applications, but it is not available to private homeowners. Silvicultural Treatment. In re- cent years, we have identified some of the factors that increase the risk of a stand being defoliated by the tussock moth. Stands located on the upper slopes, for example, are more like- ly to be defoliated than stands on the lower slopes. Stands exposed to intense solar radiation on steep, south-facing slopes are more susceptible than those grow- ing on less exposed sites. And trees growing on volcanic ash soils are less susceptible to defoliation. The condition of the stand also affects the likelihood of defolia- tion. Studies have found that the hazard increases as stand density increases. During periods of drought, denser stands are more stressed and, therefore, more susceptible. Stands with multi- storied struc

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