Pine Bark Beetles
Cooperative Extension Service, College of Agricultural and Environmental Sciences, The University of Georgia Bulletin 1097, October 1993, 8 pp.
If SPB or Ips beetle infestations are present, immediately remove all trees still infested or showing signs of attack, as well as any dead trees. An insecticide application to healthy trees in the vicinity of an infestation is advisable as a preventative measure against attack. Thoroughly saturate the bark of the entire trunk and the base of all large limbs on trees being treated. This will require specialized equipment. Check all pines in the area often with binoculars for the next several months for any signs of new beetle attack.
If BTB are infesting the tree(s) and the crown has not yet begun to fade, immediately apply an approved insecticide to the bottom eight to 10 feet of the trunk. Thorough coverage and wetting of the bark and exposed parts of the base of the tree are essential for BTB treatments. It would be advisable to apply a preventative insecticide treatment to the lower portion of adjacent non-infested pines. Make sure the attacked trees do not undergo any undue stress over the next few months. Do not trench, dig around the roots, etc. Of the attacked trees.
All trees that have developing beetle brood should be cut and removed from the site, if possible. In some cases, large numbers of developing insect predators and parasites may have not yet emerged from the tree. These insects often have longer life cycles than their bark beetle prey or appeared at the tree after the initial infestation by bark beetles. If you have verified that the bark beetles have already left the tree and the tree is not a hazard, consider leaving it standing to allow these beneficial insects to emerge to help control the future bark beetle populations.
If BTB are infesting the tree(s), it is sometimes feasible and cost effective to treat a limited number of infested trees with an insecticide to stop expansion of the spot (see above section under "In Landscape Trees").
If Ips beetles are infesting the tree(s), salvage removal, chemical treatment, cut and spray or pile and burn are the only effective management options available. If SPB are infesting the trees, select the management scheme best suited for your situation from those presented below.
- Chemical Applications -
generally are used in commercial stands only on small numbers of trees. Chemical applications for bark beetle control usually are not practical, cost effective or environmentally wise when large numbers of trees are involved.
- Salvage Removal -
is usually only feasible when arelatively large volume of wood is available and makes the operation cost effective for a logger. Prompt action is necessary to prevent significant degradation of the wood to allow for some economic return and to prevent further expansion of the bark beetle infestation. The
first step is to remove a 50-100 foot (at least one tree height) buffer strip of green noninfested trees around the most recently attacked trees. Second,
remove newly attacked trees and any trees containing beetle brood. Next, remove older standing trees from which the brood have already emerged.
- Cut and Leave -
is best used for controlling small spots (10-50 trees) when salvage is not practical or cost effective. Fell attacked trees and a border of healthy trees toward the center of the beetle spot. It may be necessary to cut limbs on the underside of the felled trees to ensure that the tree trunks are lying on the ground. It is believed that the increase in mortality caused by the high temperatures on the bark of the trees, increased humidity on the underside of the trunks, and increased predation may combine with the disruption of emergence and attack patterns to lessen further infestation of standing trees. Cut-and-leave is practical, relatively inexpensive, and requires minimal manpower, equipment and training. Unfortunately, the owner/manager realizes no cost recovery.
- Cut and Spray -
is a variation of cut-and-leave. Trees with developing brood are cut and all surfaces of the trunks and major limbs are sprayed with an approved insecticide using a small backpack sprayer to ensure that all developing beetle brood are killed. The felled trees are left in place in the forest. Trees adjacent to those cut should be checked frequently as a safeguard against possible- attack in the event that the original infestation was not completely eliminated.
- Pile and Burn -
Trees with live brood are felled, piled and burned. A distinct disadvantage to this technique is the need for heavy equipment to pile the trees so that they can be burned. Infestations in pre-commercial stands can be controlled by knocking down all the trees and burning.
- Behavioral Modifying Techniques - Projects are under way in which researchers are trying to develop SPB control tactics by manipulating the various chemicals the beetles (or their natural enemies) use to orient, attack or disperse their populations. To date, these projects have met with limited success. Some advantages of these promising methods are:
they are natural, non-toxic compounds
they may be able to be formulated for easy application by non-professional field crews or small
landowners and
they do not require the felling of trees. Perhaps in the next few years these techniques will be
available for use by timber and land managers.
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