Attack of the Pine Beetles
by Carol Rawle

Last summer, if you were cruising around the Ranch, you probably noticed many brown and dying trees. The cause is infestation of pine beetles in ponderosa and pinon pines. Because so many property owners undertake to begin clearing and grading their land in order to build during the warm months, this paves the way for perfect conditions for these pine beetles to flourish.

Mountain Pine Beetle (MPB) likes to burrow into ponderosa pines as soon as
Adult Dendroctonus Adult Ips
Adult Mountain Pine Beetle (Dendroctonus, left) versus Ips (right).  Note gradually curved wing of Dendroctonus. Actual size of Dendroctonus is from 1/8 to 1/3 inch, Ips 1/3 to 1/4 inch.
the weather turns warm in the spring. They are active all summmer long and into the fall if the weather stays warm. The IPS Beetle favors pinon pines, and like the MPB, likes to target trees that have been cut down, trimmed up, or weakened by construction activities in the vicinity. They enter the weakened tree or downed timber to lay their eggs. This causes popcorn-shaped masses of resin to form on the tree called "pitch tubes." By the time you notice this, however, it's probably too late to save the infested tree.

Large, uninfested pine being preventively sprayed.  This protects high-value trees and should be done annually between April 1 and July 15.
To prevent the new generation of beetles from spreading to nearby healthy trees, you need to treat the healthy trees with an insecticide containing CARBARYL. I recently purchased Sevin, a concentrate, from Wal-Mart at a reasonable price. To spray a large, tall pine tree, however, requires a special tree sprayer attachment for your hose, which is also available in stores. You will need goggles, mask, and protective clothing since the chemicles are very toxic.

To control pine beetles without resorting to chemical means involves some vigorous effort. The best plan is to restrict tree cutting to the cold months when the beetles are dormant, between November 1 and March 15. The next best thing is to remove cut trees to a cleared area well away from your remaining healthy trees. Then spray these piles thorughly with the carbaryl solution. To promote a healthy tree population on your land that is better able to withstand beetle attacks, you really need to thin out the trees so they aren't crowded. This allows the remaining trees to get more sunlight and to absorb more water and nutrients. A healthy tree may be invaded by beetles, but it will have the necessary vigor to survive the attack.

Pine beetle attacks are a natural occurrence in nature. However, because of increased human activity, it is made much worse. Some property owners have gone to a great deal of trouble and expense to selectively clear trees for construction, leaving the really beautiful trees to surround their new home, only to lose most of them to pine beetles which have invaded the downed timber. It's well worth the extra effort to segregate your slash piles and treat the downed wood with chemicals to avoid a massive loss of beautiful pines on the Ranch.


For more information on the Mountain Pine Beetle, see the Colorado State University Cooperative Extension page at www.ext.colostate.edu/pubs/insect/05528.html

For more information on diseases and insects of the Pinon Pine, see the Colorado State University Cooperative Extension page at www.ext.colostate.edu/pubs/garden/02948.html