Being an owner of forested property can bring many upkeep duties. Thinning, burning, roadwork and monitoring for tree health can keep a property owner busy. Many large, old Douglas-fir trees in the Double Arrow Ranch and valley foothills are showing signs of beetle attacks in the last couple years, including some trees over 400 years in age.
Last year’s beetle-infested trees can affect your healthy trees if not dealt with in a timely fashion. Most forest insect pests occur naturally throughout Montana, but with some careful planning and the right type of removal, you can prevent the spread of beetles into your forest or trees.
Douglas-fir beetle typically infests damaged, sickly, old or recently damaged Douglas-fir trees. This area is still seeing an uptick in beetle activity due to the 2017 Rice Ridge wildfire and various winter blowdown events.
These beetles are tiny, about the size of a matchstick head and thousands of them can emerge from a single tree. Keep an eye out for fading tops and red boring dust accumulating at the base of the tree to indicate an active attack in the springtime.
Once a tree is infested, it is usually dead within several months from the hungry beetles cutting off nutrient flow below the bark. Even though infested trees may still have green foliage, they are unable to survive most attacks. Once a tree is infested by bark beetles, there is no way to halt the attack. Cutting and removing these trees from the property within a year (before the next spring) can reduce future insect spread and possible death from attacks in other adjacent trees.
Landowners wanting to safeguard individual trees or an entire stand can opt to apply anti-aggregation pheromone packets called MCH (methyl-cyclohexanone) prior to April 15. These packets are not harmful to humans and act as a synthetic barrier to the beetle’s sense of smell. MCH applications only last for the summer and are specific to Douglas-fir beetle only. Beetles typically emerge from last year’s brood trees and infest new trees between April and May when temperatures are favorable.
You can order MCH locally from several vendors and they may be able to install them if needed (local herbicide dealers can also order this product):
• Swan Valley Connections (SVC) in Condon 406-754-3137
• Dillon Distributors in Missoula 406-239-5885
• CHS Mountain West Co-Op Missoula 406-543-8383
Insects, disease and wildfire do not stop spreading at property lines. I encourage developing strong connections with your neighbors to clean up heavy fuel concentrations on both sides of property lines, especially near homes. Montana Department of Natural Resources and Conservation can conduct a free home fire risk assessment to give you an idea of what you can do to limit your home’s fire risk potential. Call DNRC Fire Prevention at 406-244-2392 to schedule an appointment.
There are a lot of factors that play into an individual tree’s health. Sometimes insect activity is a part of a larger tree health issue.
Please feel free to contact DNRC Clearwater Unit Service Forester at 406-244-2382 with any forestry questions or for a free forest health consultation.
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