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Forest Pests and Treatments

Forest Pests and Treatments

Identification of a forest pest is the critical first step landowners must take when determining a solution to an insect infestation.  Some of the most common forest pests that landowners in the Northwest have to deal with are the western spruce budworm, Douglas-fir tussock moth, Douglas-fir bark beetle, mountain pine beetle, and the fir engraver.  Northwest Management, Inc. is here to facilitate forest management for landowners by identifying  the specific forest pests affecting the property and providing a solution that best fits the landowner’s goals and budget.

Our Team’s experience in all aspects of forest health treatment, land conservation, and restoration results in a highly professional set of services, consistent communication, and leadership that saves our clients both time and money.

Western Spruce Budworm

  • Identification: Causes defoliation in conifer trees turning the needles brown and ‘singed’ looking, generally only attacks new needles.
  • Tree Species at risk: Douglas-fir, Engelmann spruce, blue spruce, white fir, subalpine fir
  • Treatment: Aerial Spray with BT, silvicultural methods such as thinning.
  • Timing of Treatment: Spraying is weather dependent and usually occurs in Late June to early July
  • Application Method: NMI manages the aerial spraying on behalf of the landowner.  Annual spraying may be required until desired infestation level is achieved.  

Douglas-fir Tussock Moth

  • Identification: Causes defoliation in conifer trees turning the needles brown and ‘singed’ looking, trees can be completely defoliated
  • Tree Species at risk: Douglas-fir, in heavier infestations other surrounding conifers are also at risk
  • Treatment: Aerial Spray with BT, silvicultural methods such as thinning.
  • Timing of Treatment: Spraying is weather dependent and usually occurs in late June to early July
  • Application Method: NMI manages the aerial spraying on behalf of the landowner. Annual spraying may be required until desired infestation level is achieved.

Douglas-fir Bark Beetle

  • Identification:  The first sign of an attack will be reddish orange sawdust in bark crevices and accumulation of sawdust around the stump of a tree.
  • Tree Species at Risk:  Douglas-fir
  • Treatment: Application of MCH pheromone packet
  • Timing of Treatment: Hang packets within 5 days of April 15th.
  • Application Method:  For area protection hang packets on unaffected trees in a grid system 40 packets per acre at approximately 33-foot intervals. Packets are viable for one season. 

Mountain Pine Beetle

  • Identification: The first sign of an attack will be pitch tubes coming out of the bark of the tree. Sawdust will be evident both on the bark and gathering around the base of the tree.
  • Tree Species at Risk: Ponderosa pine, lodgepole pine, whitebark pine, limber pine, bristlecone pine
  • Treatment: Application of Verbenone pheromone packet
  • Timing of Treatment: Hang packets within 5 days of June 15th.
  • Application Method: For area protection hang Verbenone packets on unaffected trees in a grid system, 30 packets per acre at approximately 40 foot intervals. Packets are viable for one season.

Fir Engraver

  • Identification: Causes roughened misshapen bark, sporadic dead limbs, and occasionally full tree mortality.
  • Tree Species at Risk:  Grand fir, Subalpine fir, Douglas-fir
  • Treatments:  Silvicultural methods aimed at maintain forest health, pheromone packets are ineffective against fir engraver
  • Timing of Treatment: Any time once an infestation has been established can be beneficial.
  • Application Method: Silvicultural treatments.

Example of defoliation caused by western spruce budworm on a sapling sized Douglas-fir

Example of pitch tubes on a lodgepole pine caused by mountain pine beetle