In a February article, we introduced readers to our Mountain Pine Beetle (MPB) in-house science experiment. Bill Nye the Science Guy would be even prouder.
Part one began courtesy of a diligent landowner northeast of Rocky Mountain House. We obtained a sample of lodgepole pine which had been successfully infiltrated by MPB. The bolts were harvested just prior to the February cold snap.
The specimen was infected through a beetle inflight in 2018 and, although still appeared "green” and presumably alive, was truly a goner. The blue stain had effectively cut off the vertical flow of nutrients and water and the tree was dead.
That was only part of the story. The rest was under the bark. After four weeks of warming up indoors sections of bark, near pitch tubes, were peeled back revealing the distinctive, vertical "J-shaped” beetle pattern. Where the previous year beetle laid eggs were lateral galleries with munching larva.
Fast forward to March, and other pitch tube connected bark removal revealed fully developed larva and, in a couple of cases, actual 2019 beetles.
Part two of the experiment involved another section of log harvested from crown land from the first part of the February freeze. This section of lodgepole pine was warmed in similar fashion but egg to larva results were less than the January harvested logs.
Part three saw a length of log brought in March and treated the same way. The result was like the early cold snap tree with fewer beetles. The concern is the beetles, with built in antifreeze and a cozy thick layer of bark, survived the deep freeze. These sample logs were destroyed to eliminate any chance of beetle life in the summer of 2019.
Even though MPB is a native pest, each year’s beetle flight is a concern. Annual beetle flights, which begin in early July, have a lot to do with chemistry. When beetles attack, they release an aggregate pheromone that says, "here is the party, come join us”. Once a tree is overwhelmed, the beetles switch to an anti-aggregate that says, "this party is full, go find another party”.
Which brings us to the all-important matter of tree removal. The rule for crown land tree destruction is 40 or more MPB pitch tubes. The pitch tube is where the tree reacted to the MPB bore hole literally trying to "pitch” the beetle out. An overwhelmed tree, almost always a tree plus 60 years old, cannot fight off a mass beetle attack. Hence the over 40 pitch tube thresholds.
Then there is the matter of tree protection. Options are limited. There are pheromone traps that attract beetles to their collective demise. There are also pheromone products – verbenone – to fool beetles to thinking a tree has already been mass attacked.
These protection products are currently sold through private industry and, in the case of anti-aggregate simulators, in larger packaging with several pouches to a package. We are aware of two companies with the ability to sell to an end user. Please see the list at the end of this article.
If you suspect signs of MPB on public land, please contact Alberta Agriculture and Forestry. Owners of private land are responsible for pine trees on their own property, but Clearwater County Agriculture and Community Services staff are available to coach landowners on options.
What can you do?
- Be careful with firewood. If you bring firewood home from an infected tree you risk passing MPB on to trees on your property and in your neighborhood.
- Know the signs of MPB and make sure the tree you are dealing with is truly a pine and not another kind of conifer.
- Keep pine trees healthy as any tree stressed by lack of moisture, poor pruning, truck or root injury or topped are at greater risk.
- Diversify your wooded areas with non-pine species. Always be planning for the next generation of trees.
- Be realistic about life expectancy. Every tree is ultimately terminal. An end-of-life strategy for trees includes knowing when removal is necessary. Assess your pine trees before they become a problem.
- Take responsibility for trees on your own property.