Methods used to establish permanent plots in precommercially thinned and unthinned stands to monitor root disease development are described. Plots were established in 22 Armillaria-infested stands in northern Idaho and western Montana. The proportion of trees dead and infected was significantly higher for planted than for natural regeneration at the...
Three hundred fifty Leach pine cells used to grow containerized conifer seedlings at the USDA Forest Service Nursery in Coeur d'Alene, Idaho, were sampled for Fusarium and Trichoderma colonization. Cells were either sampled prior to or after cleaning. Cleaning reduced Fusarium colonization from 86 percent of the cells to about...
Investigations of containerized western white pine, western larch, and Douglas-fir seedlings at the Western Forest Systems Nursery in Lewiston, Idaho, revealed that many seedlings were colonized with Fusarium oxysporum although they lacked severe disease symptoms. White pine seedlings were also infected with Pythium spp., probably as a result of sowing...
Containerized western larch, Douglas-fir, grand fir, subalpine fir, and ponderosa pine seedlings which displayed disease symptoms were sampled for presence of Fusarium spp. Seedlings from 33 seedlots within the Northern Region were sampled. Major types of diseases included post-emergence damping-off, root disease (late damping-off), and cotyledon blight. Fusarium oxysporum was...
A rare outbreak of hemlock sawfly, Neodiprion tsugae Middleton, was detected in August in drainages near the Canadian border in Idaho infesting several thousand acres. Some stands of western hemlock and subalpine fir were severely defoliated. Understory Engelmann spruce trees were lightly defoliated. The sawfly overwinters in the egg stage...
Insect damage was extensive to Douglas-fir, ponderosa pine, western white pine, and western larch cones at most seed production areas surveyed in 1979. From 70 to 100 percent of the cones from several collecting periods were injured. Moderate damage (40-70 percent of cones injured) occurred to Douglas-fir, ponderosa pine, western...
Western spruce budworm defoliated area in the Northern Region has differed significantly across three discrete geographic zones during the past decade. Aerially visible defoliation in northern Idaho increased from 1.7 million acres in 1969 to a high of 2.2 million acres in 1974, and declined to none in 1979. Defoliated...