Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, March 21, 1993 TAG: 9303190249
SECTION: EXTRA PAGE: 21 EDITION: METRO
SOURCE: Patricia Held
DATELINE: LENGTH: Medium
PINE BEETLES POSE A SERIOUS PROBLEM
Virginia landowners should be on the lookout for a serious pest, says Virginia State Forester Bob Kennedy. We are in the midst of an epidemic of Southern pine beetles."We've had outbreaks before," says Kennedy, "but it is worse this year than in the past." The beetles first showed up last spring, and already foresters have identified hundreds of infected areas in our vicinity.
While Eastern Virginia and the Piedmont expect to be the worst hit, any area with populations of Southern pine can be affected. It's rare for the Southern pine beetle to attack white pines, but other types of pine in the area are targets.
Groups of red- and yellow-topped pines are among the first indicators of a pine beetle invasion. Evidence of attacks can be found throughout Campbell County and parts of Bedford County. While the Roanoke area has not been as hard hit, Kennedy says that masses of red-topped pines can be seen on Purgatory Mountain as well as in the mountains just west of Big Island.
According to a pamphlet put out by the Virginia Department of Forestry, during beetle outbreaks, "trees that are stressed from competition, injury, drought or old age are most likely to die; but any pine can be killed if beetle populations are large enough."
Researchers are not sure exactly why beetle outbreaks occur or why they end. But rarely do they last for more than four years.
The Southern pine beetle is small, only about an eighth of an inch long. Adults bore through bark and lay eggs where the bark meets the wood. These eggs hatch into tiny cream-colored grubs that feed under the bark.
To determine if pine beetles have infected a tree, look for red- and yellow-topped and bare pines. Also, look closely at the trunks for small splotches of pitch "like little pieces of popcorn," where beetles bored into the tree. Finally, shave off a piece of bark from suspected trees and look for the developing beetles and characteristic S-shaped patterns that they leave beneath the bark.
Heavy attacks kill the trees by disrupting the normal movement of water and nutrients. Beetles introduce a fungus into the tree that plugs up the water-conducting tissue.
Once the tree is infected the beetles move onto the next pine. In the summer the foliage of the infected trees gradually turns from green to yellow and then to reddish-orange before the needles drop off and the bark peels away. As spots grow they include all stages of dying trees from green to yellow, red and finally bare trees. Since beetles are usually long gone before the tree appears to be dying, green trees in an infected area should also be suspected of being infected.
Once trees are infected they die. Natural predators include woodpeckers and other insect-eating birds. These can help prevent a spot from getting bigger.
To control the spread of the beetles, foresters recommend removing all infected trees plus a buffer of all green trees within a 50 foot area of pines with red tops. Even if it is impossible to remove the trees, Kennedy suggests that infected trees be cut down. The pine beetle is a weak flier and has trouble moving to adjacent trees once its host is on the ground.
Landowners who suspect they have a Southern pine beetle infestation problem should call their local Virginia Department of Forestry office for an inspection of their trees.
Readers' notes: In reference to a recent article on cavity-nesting birds, I received a letter from Donald J. Davis, an extension agent in the Lynchburg office. He passed on the following information:
Birds, including many cavity nesters, are effective controls of gypsy moth caterpillars. In some cases, one forested area might be devastated by these caterpillars while another nearby escapes. If conditions are right to support a predator community such as cavity nesters, the caterpillars can be controlled.
A stable mixed forest includes several cavity-nesting birds that eat gypsy moths. These include nuthatches, starlings, woodpeckers and chickadees. The birds feed on young caterpillars and to a lesser extent, older larvae. Chickadees feed on all life stages, including egg masses.
Other birds as well feed on gypsy moth caterpillars. Orioles, warblers, vireos, tanagers, blue jays, blackbirds and robins can be attracted to nest in your garden by providing nesting material such as wool, string and twigs. These nesting materials can be placed in an old suet feeder to make them easily accessible to the birds.
Davis' source for this information is an article written by Steven G. Meeks, gypsy moth program manager from Albemarle County.
Patricia Held will respond to readers' questions on the plant and animal wildlife in the region. Mail inquiries to: Patricia Held, P.O. Box 65, Goode, Va. 24556.
Patricia Held is a Bedford County free-lance writer and author specializing in natural history.