A practical demonstration of a method for
rating forest stands as to their probability of
defoliation by the Douglas-fir tussock moth
using aerial photographs and available cruise
data was done in the Palouse Ranger District,
Clearwater National Forest, Idaho.
A nonlinear computer program, RISK, was used to
identify significant independent...
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...
1. Defoliation by cankerworms in 1979 was significantly less in 1978 treated shelterbelts than in untreated shelterbelts. 2. Most shelterbelts treated in 1978 retained enough foliage by late June 1979 so that adjacent crops were protected from wind. 3. Aerially applied Bt at a rate of 1/2 lb./acre provided shelterbelt...
The forest tent caterpillar, Malacosoma disstria Hbn., began defoliating trembling aspen stands, Populus tremuloides Michx., in 1976 in the Turtle Mountains of North Dakota. Heavy defoliation was scattered through about 150,000 acres in 1978. Pupal mortality from parasites and disease was almost 100 percent in cocoons on understory shrubs and...
Based on per acre costs, plantation establishment is one of the most expensive silvicultural practices (Pfister 1976), but only token studies have been done on frequency and causes of seedling injury and mortality in Region 1 plantations (Wenner 1976). Therefore, we conducted a survey in 1978 on four National Forests...