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Southern Pine Bark Beetles: Pest Alert (Kauffman, 2001):
Species affected: All southern yellow pines, including short leaf, loblolly, Virginia. Also, eastern white and Scotch pine. Trees <10’ tall (<3” diameter) generally not infested.
Urban environment effects: Disturbances include altered temperature and drainage, changes in exposure to chemicals and nutrients, sudden exposure of stems to direct sunlight, mechanical damage to stems/crowns, damage to roots by digging, grading and compaction. These events often cause heavy stress, reduced vigor and weakened defense systems in pines.
Beetle interactions: A tree may be killed by a single species of bark beetle, but each of the five beetle species is typically found in certain portions of trees.
Symptoms of attack: Early detection and prompt action are essential to minimize pine bark beetle damage. Periodic tree inspections assure more timely detection of infestations. Boring material (ground bark and hardened resin) is the first external symptom of attack, found in bark crevices and on spider webs and under story plants. Pitch tubes (masses of resin) on the bark surface often mark the entry points.
Healthy trees attempt to capture the beetles on entry by these pitch tubes (popcorn size blobs of pitch. Keeping trees watered will help trees be able to form the pitch tubes.
Discolored foliage is usually the first symptom noticed by homeowners. Needles fade to yellow-green, then to red or brown, and eventually fall from the tree. In most cases, by the time the foliage turns red, new beetles have emerged through pinhead-sized holes and moved on to other trees. Egg galleries on the inside of bark of attacked trees have distinct traits to identify the species causing the damage.
Prevention: Promoting good tree health minimizes the chances of bark beetle attack and spread. Thin dense stands to reduce competition in the urban setting. Leave healthy young trees with full crowns, but remove diseased or severely suppressed trees. Encourage a mix of tree ages and species, including stress tolerant types. Water deeply during dry periods and fertilize properly.
Curative: All infested trees must be removed, and the debris either carried off-site, or burned or buried. Trees with bark peeled off to expose the wood beneath should be cut and removed. It is possible that some trees with discolored needles may be saved, but it is not likely.
Insecticides: Some formulations of lindane and chlorpyrifos (Dursban 4E, Cyren 4E) are registered for prevention and control. Proper spray coverage and frequency are essential. Limit use to special situations with high value trees in danger of attack.
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