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Mountain Pine Beetle

A number of customers have asked if they should avoid planting pines because of the pine beetle.

This is not a new problem. MPB has flared up and died back repeatedly. It's currently on the rise in part because of warm winters, in part because of fewer forest fires, in part because of certain logging practices.

Almost all trees have some pest that attacks them. Many pests come and go in cycles. Currently, because of a series of warmer than average winters, the pine beetle population has grown. For pines, it can be MPB. For birch it can be leaf miner. For spruce it may be spruce bud worm.

A pine in good health is largely unharmed by the beetle. It will bore into the tree. The tree responds with a flood of pitch, and smothers the beetle.

A pine in poor health can't produce enough pitch.

But ...

(There's always a but.)

In a stand of older pine, near the end of their life and we have a couple of warm winters, the beetle population explodes This huge overpopulation of beetle can swamp nearby healthy pines just because so many attack the tree that it runs out of sap.
Add one more victim.

The beetle is subject to a bunch of predators, mostly small wasps, and a few diseases. These are effective at the normal population levels. They fall behind when the population explodes. By the time they catch up, it's too late for the pines.

More information: Colorado State Extension Service Mountain Pine Beetle

Parks Canada: What is Mountain Pine Beetle?

Recommendations

If you are near an extensive area of pine forest that is fairly mature (most trees are more than 8" thick, more than 40 feet high, then you may want to hold off a bit on pines. Or you may want to plant pines now, hope that the beetles ignore them because they are so small, and when the epidemic dies out you can be the only person on the block with pines.

Bristlecone pine is somewhat less susceptible. Be prepared to wait. They are very slow growing trees.

Keep your pines healthy. Mostly this means reducing stress on them. Light, fertilizer, water, room. Take out the overcrowded ones.

Watch your pines for signs of infection. See article links above.

In general the beetles prefer older trees. Young trees (under 4-6" diameter are not attacked unless there are very large numbers of beetles.

While strong winds have carried beetles hundreds of kilometers, most beetles attack a nearby tree. If you have no major pine stands within 10-20 kilometers or so, the chances of a young pine getting an overwhelming exposure to beetle is small.

Focus on diversity. It's far more important in ecology than it is in economics. Pests have a much harder time spreading if their host is 20% of the landscape instead of 100% of the landscape. Use multiple species, at multiple ages.

Avoid mass plantings. It's easy for an infected tree to infect it's neighbor. Avoid formal arrangements -- a row of identical trees. If you have to remove an infected tree, there's a big hole in the landscape.