Piled Pine Debris An Invitation To Beetles

Many of the region’s trees were seriously damaged in the November ice storm and by severe winter weather. Now that the snow’s melted, it seems there’s debris everywhere.

If left on the ground, the tree branches and other debris are problems. Here’s why:

If left piled, the debris from pines - tops and branches known as slash - can create spring breeding sites for an insect pest called the IPS pine engraver beetle. When adult beetles emerge from pine slash piles in summer, they then attack healthy pines. All fallen trees and tree tops should be removed from your site, burned (where allowed), or chipped by May 1 to prevent beetles from spreading to other trees. Thinly scattered branches will soon dry out and not be suitable for the beetles.

When the beetles infest a tree, it usually results in a dead top. The tree is then weaker and subject to the attacks of other pests such as the Western pine beetle, which will actually kill the tree. Healthy green trees are seldom infested with these beetles.

Many insect pests move into broken pine trees with little or no foliage left. The snags will eventually decay and fall. The decision of whether to remove the snags should include a discussion of aesthetics, potential hazards, timber salvage value and wildlife value.

Give the benefit of the doubt to broken trees with an estimated 50 percent or more of the foliage left. These may live. Leave them standing, monitor them and, if practical, water them through the summer.

The Douglas fir beetle will attack damaged Douglas fir tree debris anywhere, usually in late April to early May. These beetles are good flyers so they can travel long distances looking for suitable downed trees and piles of branches. The next generation emerges the following year, which gives us time to deal with this insect problem. While it’s best to remove the downed trees and broken tops this spring, if this cannot be accomplished, the work can be done any time during summer or fall. The standing portions of damaged Douglas fir trees don’t interest bark beetles so they can be left as wildlife habitat.