Invasive Species Control

by Maria Janowiak

An unwelcome present arrived under some Oregonian Christmas trees.

The Oregon Department of Forestry discovered that Christmas trees shipped to big box stores such as Walmart were infected by the elongate hemlock scale. This pest feeds on the underside of needles and leaves behind a waxy residue that diminishes the tree's health. If the scale spreads into the natural forest, it could have a devastating impact on fir, spruce, and iconic Douglas fir trees. 

Ponderosa pine forests of the Southwest are home to the native bark beetle. However, human influence, denser forests, and increased temperatures and drought events have led to recent bark beetle outbreaks that threaten the health of ponderosa stands. Where dead trees stand, fire can move as much as three times more rapidly, creating dangerous conditions for firefighters and residents. Restoration treatments can be used to help restore the balance needed in ponderosa pine ecosystems.

What do all these insects have in common? They were all brought to North America from Asia or Europe. These exotic insects have caused havoc in our forests because the trees they attack have developed little resistance to them. Our forests are filled with native insects that attack and sometimes kill trees, but because these insects evolved along with their hosts, they don’t cause complete mortality that non-native species can.

Buckthorn is the bane of many woodland owners. It turns out that buckthorn is starting to appear on the radar of soybean farmers as well (see post titled “What do buckthorn and soybean have in common?” for details).