By: Devin Healy, Forester, Northwest Management, Inc.
Spring is almost here and with spring comes the first flight of the Mountain Pine Beetle (MPB) for the year. Vast swaths of North America are infected with the MPB, an estimated 2.7 million acres in Montana alone. One of the tools that land owners and managers have at their disposal to deal with this epidemic is verbenone.
Verbenone is a synthetic pheromone treatment that replicates the anti-aggregate pheromone Mountain Pine Beetles (MPB) emit when attacked trees are fully occupied. The pheromone repels beetles from further attack and encourages them to seek unoccupied host trees. Verbenone is considered to be non-toxic to humans, pets, birds and even the beetles themselves. Verbenone can be considered one tool for MPB protection. Other tools include tree spraying and long-term forest management treatments.
Results of verbonone use are highly variable. In some instances verbenone has failed to provide protection while in others verbenone has been shown to be highly effective. Some level of MPB mortality can generally be expected. Verbenone is not recommended if more than 15% of the forest stand is already infested and the infested trees cannot be removed prior to beetle flight. Results can be improved if infested trees are removed prior to the application of verbenone. Verbenone packets should be installed in mid-June. The packets can be simply nailed or stapled to trees.
There are two basic ways that verbonone is deployed, one being individual tree protection and the other being area wide. For individual tree protection use two 7- or 7.5-gram packets per tree. For larger trees (>24 inches diameter) use 3-4 packets. On smaller trees attach packets on north side of tree. On larger trees spread them on all sides. Place them 10’ high if safely possible. For area wide protection evenly distribute 20-40 pouches per acre depending on intensity of surrounding infestation. Use this as a guide for area wide distribution; 20 pouches per acre –place on 47’ grid, 30 pouches per acre – 38’ grid, and 40 pouches per acre – 33 foot grid.
It is important to remember that verbenone is not a silver bullet, particularly in areas that already have high rates of infestation. Verbenone may not be as effective if used in area with prolonged infestations if used over and over in the same stand. Verbenone is more effective when used in conjunction with silvicultural treatments.
Northwest Management, Inc. will be selling verbenone this year and orders can be placed online. For more information please visit www.consulting-foresters.com.