Douglas L. Airhart & Guy Zimmerman III
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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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Purpose Right Tree / Right Place Selecting Trees Transplanting Trees Mulching & Staking Summary Diagram Pruning Trees Topping Hurts! Protecting Trees Tree Root Myths Pine Bark Beetles Live Christmas Trees Glossary List of Figures List of Video Vignettes Related Links Bibliography
TLCforTrees.info is maintained by: Douglas Airhart, Ph.D. Certified Arborist & Jeff Plant, Ph.D, Last Updated on: 07/11/03 |
