Saturday, August 10, 2013
Unfortunately, one doesn’t have to look far to see the increasing evidence of the latest beetle to wreak havoc on our pine trees. The standing dead trees seem to be everywhere, with more visible every week. From the old giants at Jackson Park and the entrance to WalMart, to those dotting the hillsides in town and up the valley, the dry, red shapes of dead pines are easy to spot.
At a meeting on July 17 at the Mosier Grange conducted by Chet Behling of the Oregon Department of Forestry, lots of questions were answered. Sadly, the answers were not encouraging.
While beetle kill has been a fact of life in the forest, the latest culprit seems to be the California 5-spined Ips beetle. This small insect (3mm) has worked its way up from California, up the Willamette Valley, and was first reported in the Gorge in 2010. Infestations are at their worst during times of high tree stress, such as drought, following fires or wind and ice storms (such as the one we experienced in 2012) where large numbers of trees are injured. The beetles are attracted to scent from the wounded trees, and burrow into the bark chewing networks of tunnels where they lay their eggs. The mature beetles emerge in as little as two weeks to find their next victim. There are two main hatches or flights, one in July and the second in September or October. They can infest many species of pines, including ponderosa, sugar pine, western white pine, lodgepole, Monterey hybrids, and ornamentals.
The disheartening news is that, while outbreaks typically peak in one to two years, we are in Year four of this one with no relief in sight. Insecticide sprays, systemics, pheromone treatments and watering seem to have little or no preventive effect. Tree removal and pruning should be avoided until after the October flight to avoid releasing the scents that attract new beetles. Removing the dead trees between mid-October and January, while the beetles are dormant, is the safest bet. But all debris must be removed, chipped or burned to prevent reinfestation. Wood cut for firewood must be debarked.
If there is any good news, as long as there are no further fires or storms creating slash and stressed trees this year, beetle populations are expected to return to normal according Todd Murray of WSU Skamania County Extension.
Marg Guth lives in Pine Grove.