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Disposal and Removal of
Infested Trees
When mountain pine beetles are in an area, one treatment that can have some benefit is removing currently infested trees. This is most effective when the beetle population is low to moderate and can be used in conjunction with other techniques, such as preventive spraying or the use of anti-aggregating pheromones. Once the beetle population is at high levels, removing infested trees is of less benefit.
If thinning is to be done in an area with active beetle population, it is best to remove all infested trees as part of the operation.
Covering as much area as possible during the removal process will increase the chance for success. This may require neighbors coordinating their activities.
Before removing any trees, those that are currently infested by mountain pine beetle must be identified across the entire area. This is best done after beetle flight in the fall. These trees will still have green needles at this time, but other characteristics are available to identify those infested (see MPB Infested Trees). Beetles have already left trees with red or brown needles and their removal will not affect the population, but it may reduce the risk to public safety from tree failure and decrease the amount of fuel.
Once infested trees are identified, the land owner can determine the best way to treat them, whether by hiring a contractor or doing the treatment themselves. Cutting the trees and leaving them untreated on site does not affect beetle populations. Beetles will continue to develop and emerge the following summer. Infested trees need to be removed from the site or treated in some way to destroy the developing insects before the new beetles emerge and fly the following year, which normally occurs from July to August.
Removing Infested Trees
Several options are available for removing infested trees. If logs are not to be processed promptly, they should be removed to areas without nearby host trees to avoid spreading beetles. Two options are as follows:
Harvest and take logs to a mill
Haul to a central community processing or disposal area. Severely impacted communities may consider creating a location where infested material can be taken and processed to reduce the beetle population. This provides possible economic benefits by increasing the supply of material for marketing and sale.
On-Site Treatment of Infested Trees
Several options are available for treating infested trees when they cannot be removed from the site. All material greater than 4 inches in diameter needs to be treated. Any of these treatments need to be done before beetle flight the next year.
Cut and use as firewood as long as it is used the same winter. Cut into firewood lengths, split, and spread out in a sunny location to accelerate drying.
Do not stack. This should be done by March at the latest to be effective since 6 to 8 weeks of drying is required. If wood can’t be split, scoring it lengthwise several times around the bolt with a chainsaw down to the wood will accelerate drying.
Burn on site. Be careful not to damage surrounding live trees.
Bury on site.
Chip on site.
Chips can be hauled off, used as mulch, or dispersed through the forest.
Remove the bark down to the wood. There are several handheld and power tools available.
In warmer climates covering infested logs with clear plastic has been shown to be occasionally effective in killing developing beetles. Cooler weather conditions in Montana, and a general lack of success in this practice, result in our not recommending it.
