A 3-year evaluation of Douglas-fir cones in Montana and Yellowstone National Park, Wyoming, showed the western spruce budworm, Choristoneura occidentalis Freeman, and midges were the most common and injurious insects found each year. Injury was so severe at some plots that no sound seeds could be found.
An active infestation of ash borer, Podosesia syringae (Harris) was detected in green ash, Fraxinus pennsylvanica Marsh, surrounding the Bowman-Haley Reservoir in 1973. A survey in 1974 showed that 40.4 percent of 690 trees examined contained active ash borer attacks. Forty-three out of 140 windbreaks were sampled and each one...
A survey to determine distribution and intensity of cankers and associated damage in North Dakota windbreak plantings of Russian-olive and Siberian elm was conducted in 1972. Four hundred and thirty-five (76 percent) of 574 Russian-olive examined had cankers, and 552 (72 percent) of 769 Siberian elm examined had cankers. Cankers...
"Holes" with dead, dying, and downed trees in the forest canopy could be reliably identified on 9- by 9-inch Kodak Ektachrome Infrared Aero film 2443 as root disease centers. Film scales larger than 1:4000 were best for detection of these "holes."
Most commonly occurring causal organisms in root diseased trees...
The last outbreak of the Douglas-fir tussock moth, Hemerocampa pseudotsugata McD., in the Northern Region subsided in 1965. Tussock moth populations were not detected again until 1970 when ornamental spruce were defoliated in Spokane, Washington, and Poison and Missoula, Montana.
A study was made to determine the distribution of parasites of the larch casebearer, Coleophora laricelia, within crowns of western larch, Larix occidentalis. The most common parasites recovered in order of their abundance, were: Agathis pumila (Ratz.), Diciadocerus sp. near westwoodii, Spilochalcis albifrons (Walsh), and MesopoZobus sp. Parasitism by A....
Dwarf mistletoes exert an impact on forest productivity, but this impact can be reduced through management practices. Even infested stands can yield considerable volumes if proper control methods are used. Projections of future yield increases due to control efforts are made. Cost of treatment in fiscal year 1973 was $51...