No long-term impact of carbaryl treatment on western spruce budworm populations and host trees in the Malheur National Forest, Oregon
1995
Torgensen, T.R. | Powell, D.C. | Hosman, K.P. | Schmidt, F.H.
The effects of a single application of carbaryl on western spruce budworm (Choristoneura occidentalis Freeman) populations on the Malheur National Forest in northeastern Oregon were examined for 7 consecutive years beginning in 1983. Budworm control was evident only in the treatment year, 1983, and the next, 1984. There was little difference in the pattern of budworm population behavior between treated and untreated sites during the 7 yr study. Defoliation of Douglas-fir and true firs was reduced slightly by the carbaryl treatment, but did not translate into increased radial growth. On the contrary, there was a general decline in annual radial increment among host trees in both treated and untreated areas from 1980 to 1987, presumably because of chronic defoliation.
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