Field Evaluation of Baculovirus Stocks Against Douglas-fir Tussock Moth in British Columbia12

Abstract

Aerial applications of 3 baculovirus stocks were tested against Orgyia pseudolsugata (McDunnough) in British Columbia in June 1975. A dosage of 100 billion polyhedra/acre, formulated in a molasses and a nonmolasses formulation and applied at 1 or 2 gal/acre, provided population control and excellent foliage protection. Larvae collected from the treated areas 5 days after spraying showed virus infection rates that ranged from 60–87%. With the exception of one treatment that was applied under extremely adverse meteorological conditions there were no significant differences between virus treatments. Population densities were reduced by more than 90% at 21 days posttreatment, and no evidence of survival to the pupal stage was found on the virus-treated areas.