The Rate of Crown Fade of Trees Killed by the Douglas-Fir Beetle in Southwestern Oregon

Foliage of Douglas-fir trees, observed for two seasons following lethal attack by the Douglas-fir beetle turned color at different rates depending upon weather patterns. In 1964, a cool and wet year, some killed trees faded in July, but most did not turn until after May 1965 and continued until that fall. In 1965, a warmer and drier year, 70 percent of the trees attacked in the spring were red by October as compared to 25 percent in the same month a year previously. By July 1966, all trees attacked the previous year were bare.