OLYMPIA – The mortality rate for young Douglas fir trees throughout Western Washington is on the rise due to drought-like conditions late last summer and this spring, according to state Department of Natural Resources officials.
DNR’s Forest Health Program has examined affected trees at several sites from Shelton, DuPont, and Auburn, south to Vancouver, and along the Columbia River Gorge. Douglas firs that are between 5 and 15 years old appear to be the most commonly affected, but some larger trees are also showing symptoms including entirely red crowns, red tops and red branches.
Damage has been most severe in areas with rocky soils, such as glacial outwash around the Puget Sound. Water drains quickly in these soils, and trees depend on occasional rains during the summer to replenish their water supply.
The majority of trees examined show no indication of being killed by pathogens, insects or other animals. Fortunately, even in the hardest-hit stands, the majority of trees received adequate water and are unaffected.
Landowners may see an increase in the number of red trees as the weather heats up, but if green trees have put out a flush of new, expanding bright needles on branch tips this spring, they are likely to survive.