Forest Pest Control
Douce, G.K., Moorhead, D.J., and Bargeron, C.T., Forest Pest Control, The University of Georgia, College of Agricultural and Environmental Sciences, Special Bulletin 16, Revised January 2002.
Several kinds of mammals and two kinds of birds sometimes damage living pines in the South. Their damage may vary from insignificant to serious. The mammals—deer, rabbits, squirrels, and other rodents—are the most serious pests. Mammals prefer to feed on plant materials that have been fertilized and have a high moisture content. Periods of drought may intensify the damage of certain rodents, when they may eat bark for moisture. Some of these animals are protected as game animals, and permits are required for control harvests outside of normal hunting season and bag limits. Check state and local regulations before acting.
Rabbits commonly found in the southeast are cottontail rabbits, marsh rabbits and swamp rabbits. Nearly all southeastern forest habitats have at least one species of rabbit present. Rabbits prefer brushy vegetation that offers ample cover for hiding. Although rabbits are not normally destructive to well-established forest trees, they can cause considerable damage to nurseries and portions of newly planted stands by nipping off seedlings. Rabbit cuttings look different from deer browsing because the cut edges are smooth, as if done with a knife. Deer have only upper front teeth and must pinch and pull stems, which leaves a broken end. Chemical repellents can stop rabbit damage temporarily. Thirty-inch high woven mesh fences will exclude rabbits from nurseries. Box traps and shooting (if permitted) can reduce rabbit numbers in damage areas. Removing brush piles and other cover areas may be effective in reducing high rabbit populations.
The most serious deer damage occurs from browsing on seedlings in nurseries and in young plantations. Deer frequently damage saplings by rubbing them with their antlers (Figure 55). This rubbing behavior, which may remove the bark, is usually associated with the breeding season in the fall and early winter. Damage may be reduced with chemical repellents or eliminated by excluding deer with suitable fences. Shooting can reduce deer numbers in damage areas. However, deer are protected game animals, and a permit is required to shoot depredating deer when the hunting season is not in effect.
Tree squirrels, including the gray squirrel and the fox squirrel, are known to cause damage to trees by chewing
Figure 55. Slash pine rubbed by deer,
Gerard D. Hertel, USDA Forest Service.
bark from trunks and branches. Fox squirrels are particularly likely to damage pines. This damage occurs sporadically and is associated with high populations of these animals. Squirrels have two breeding seasons per year. Their populations may have periodic highs and lows not associated with losses due to hunting. Squirrels may also cause damage by feeding on pine cones in seed orchards. Intensive hunting can reduce squirrel damage in some cases where permitted.
Beavers are probably the most serious animal pest of timber in the Southeast. Beavers construct dams which flood forest land. They also girdle stems and fell trees (Figure 56). Persistent removal of beavers with appropriate traps, combined with destruction of dams, can effectively reduce beaver damage. (Before undertaking such control tactics, obtain appropriate permits.) Although beaver populations increase slowly due to their low reproductive rate (two young per adult female per year), check for beaver damage periodically and trap if necessary.
Figure 56. Beaver-felled tree,
James Solomon, USDA Forest Service.
Cotton rats have medium brown, grizzled fur and are about 8-10 inches long, including the tail. They are known to chew the bark from young pines up to a height of about 10 inches. This damage is sporadic and occasionally serious in pine plantations under four years old. Since cotton rats prefer dense cover, keeping the area around the young trees clean through herbaceous weed control will help to reduce cotton rat problems.
Pine mice are small, short-tailed brown mice about four inches long. Although they may occur throughout the Southeast, they are rare in many areas. However, local populations may explode and cause serious damage, especially to small trees. They chew the bark from roots below ground and stems of saplings up to a height of about four inches.
Pocket gophers have a stocky body about 7-8 inches long, a large head, and an almost naked tail. The forefeet have long, heavy claws for digging. The burrows are often marked by sand mounds at the surface. Pocket gophers avoid heavy clay soils and wet areas. They can harm orchards by their damage to large roots. Pocket gophers are not usually a pest in forest conditions.
Two kinds of woodpeckers may peck holes in live trees. The yellow-bellied sapsucker makes horizontal lines of small holes on many kinds of trees (Figure 57). The bird returns periodically to freshen the holes and feed on the sap welled up in them. The red-cockaded woodpecker, an endangered species, makes its nest by excavating a cavity in large pines exhibiting old growth characteristics, frequently in trees with red heart disease. Neither of these woodpeckers does significant damage under usual forest conditions, and both are protected by state and federal laws.
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Figure 57. Yellow-bellied sapsucker
adult and damage, James Solomon,
USDA Forest Service.