Direct Control

Direct control measures result in immediate mortality to the pest population. There are various silvicultural, sanitation, and chemical methods employed to combat forest pests.

Silviculture

Cut and Leave Control Method

Silvicultural methods for controlling pests include practices that favor the appropriate species for the site or increase the vigor of the plants left on the site. During site preparation, thinning, or any other stand improvement activities, opportunities exist to favor the healthiest and most natural components of an ecosystem. Normally, vigorous, mixed-age and mixed-species forests are more resistant to devastation by native pests than are single-species plantations. Examples of silvicultural prescriptions might include: 1) cut and leave—infested trees are felled toward the center of the spot to allow for maximum exposure of the infested portion of the bole to the sun; 2) cut, pile, and burn—infested trees are felled, pushed into a pile, and burned; and 3) cut and spray—trees are felled, and their boles are sprayed with an approved insecticide. Cut, pile, and burn methods will have limited use because of their cost and the problems associated with smoke.

Sanitation

The sanitation cutting method involves removing infected or pest-infested materials from an ecosystem in an attempt to reduce or eliminate pest impact in response to pest outbreaks, or as a part of regularly scheduled stand maintenance activities. Affected trees are selectively removed, leaving the healthy vigorous ones. Sanitation can be highly effective if symptoms are readily visible. However, where symptoms are masked, large numbers of infected or infested tees may be left.

Prescribed fire is often used to suppress pests either by killing them or destroying or modifying their habitats.

Chemical Control

When properly applied, pesticides are very useful in suppressing or eradicating pest organisms. Pesticides used in the southern forests include insecticides, herbicides, rodenticides, and fungicides (USDA Forest Service 1992).

Pesticides can suppress pest populations by killing the pests outright or by moderating their activity. They may be applied from the air or the ground. New pesticides have been developed that kill only the intended pest or affect a very limited number of target organisms. In southern forests a limited number of treatments (2-4) in the 40- to 120-year rotation will occur.

Despite an impressive record of success in controlling pests, and progress to improve their selectivity, pesticide use in the South has declined steadily in numbers of acres treated as well as in rates of pesticide applied per acre. Data are not available on pesticide use on industrial and private land in the South. It is believed that the downward trend in pesticide use is not as marked on these lands as it is on National forests.