AUBURN, Ala.—Lingering drought in Alabama is causing issues for foresters managing rural and urban tracts of timber. Recent rains provided temporary relief for farmers planting spring crops, but droughty conditions linger as more than 50 percent of the state is still considered abnormally dry.
Alabama Cooperative Extension System Forestry, Wildlife and Natural Resource Management agent Dr. Beau Brodbeck said it is important to correctly identify pine bark beetles in order to properly treat them, though in most cases it may be too late to save the trees.
Correctly Identifying Pine Beetles
Several species of bark beetles affect pines in southern urban landscapes. These beetles include the black turpentine beetle (BTB), Ips engraver beetles and southern pine beetles (SPB).
“For homeowner management, it is most important to distinguish Ips and SPB from BTB,” Brodbeck said. “Both Ips and SPB beetles introduce blue stain fungus, which cannot be treated and will often result in tree mortality. BTB seldom carries the fungus and does not always kill trees.”
Brodbeck said it is important to note more than one species of beetle can be found in an infested tree. Differences between beetles are subtle; however, several key points may help homeowners distinguish the beetles.
Black Turpentine Beetles
- BTB attack from the ground up to 8-10 feet high on the stem.
- Dried resin from pitch tubes is larger than Ips or SPB and are about one inch or the size of a quarter.
- Dried resin from the pitch tubes is purplish to reddish in color.
- Attacks typically occur on damaged trees or on stumps of recently cut trees and may spread to adjacent trees.
- Healthy longleaf pine and slash pine often survive BTB attacks, even with no treatment.
Ips and Southern Pine Beetles
- Attack along the whole trunk, often moving from the upper canopy towards the ground.
- Pitch tubes are much smaller, about the size of a dime.
- Pitch tubes are a soft pinkish-white when fresh and turn a hard white and eventually yellowish color and resemble popped popcorn.
- If you remove dead bark the wood will have carved etchings in a “Y” or “H” shape for Ips and “S” or serpentine shapes for SPB. Larvae feeding on the cambial tree tissue create these carvings.
- Pines attacked by Ips or SPB beetles will often result in tree mortality.
“In most cases it’s too late to save a trees once they have been infested—with the possible exception of BTB,” Brodbeck said. “Instead management is aimed at preventing the spread of pine bark beetles.”
Pine beetles are not great flyers and cannot buzz from a beetle-ridden tree in your front yard to one in the backyard, but they can easily glide to neighboring pines. Trees standing in close proximity or within 20 to 50 yards of an actively infested tree are at greatest risk.
Begin by regularly inspecting pine trees for pitch tubes—especially those with potential exposure to stressors (construction damage, lightning strikes or drought).
After identifying beetles, use integrated pest management short- and long-term management strategies.
Short-term Management Strategies
Implementing short-term strategies helps deal with currently infested trees and prevents the spread of the pest.
- Identify the type of beetle impacting your tree (BTB is treatable).
- If the tree has Ips or SPB remove the tree immediately and grind the stump.
- Consider using chemical treatments on neighboring pines to prevent the spread of pine beetles.
Long-term Management Strategies
Long-term strategies help to ensure the future health of the tree to reduce stressors.
- Maintain a healthy tree by watering regularly during periods of prolonged drought.
- Mulch the areas around trees to help hold soil moisture, avoid soil compaction, and grass maintenance damage.
- Avoid damaging the trunk or roots with lawn equipment or construction. The resinous smell from fresh wood wounds is known for attracting beetles.
- Remove fresh broken limbs or snags to avoid attracting beetles.
- Avoid soil compaction by not parking inside the tree’s dripline.
- Thin overcrowded pine stands to improve tree health and vigor.
Pine Beetle Preventative Treatments
Brodbeck said there are several chemical products and one density regulator pheromone labeled for pine bark beetles. Each of these products has both benefits and drawbacks to consider in relation to specific trees, sites and possible impacts to non-target species and applicators.
Treating Black Turpentine Beetles
Because they seldom introduce blue stain fungus, BTB do not always kill trees and have the potential for control.
The same chemical products recommended for prevention can be used for treatment of infested trees. The insecticides are contact products, and because beetles are beneath the bark they may be difficult to reach. Consequently, control levels will vary. Spray the bottom 12 to 15 feet of the tree according to the label. Monitor the tree for infestation from Ips and SPB, as it is common for BTB attacks to lead to other pine beetle infestations.
Featured image by Ronald F. Billings, Texas A&M Forest Service , Bugwood.org. Black Turpentine Beetle infestation in Loblolly Pines.