Recommendations for control of cone and seed insect pests of black spruce, Picea mariana (Mill.) B.S.P., with insecticides

摘要

Two sets of trials on the control of cone and seed insect pests were carried out: (1) in the Skurban seed orchard, Ontario (Canada) in 1995, on black spruce seedlings planted in 1982; and (2) in the Aubrey seed orchard in 1994 and 1995, with black spruce grafts established in 1975-84. At Skurban, foliar sprays of dimethoate (1.25 g AI per tree) and permethrin (0.028 g AI per tree), applied to runoff one week prior to female flower bud flush, significantly reduced flower abortion, cone grazing, andshoot grazing caused by spruce budworm (Choristoneura fumiferana) larvae, as well as damage by the spruce cone maggot (Strobilomyia appalachensis). Compared with these 2 chemical treatments, treatment with Bacillus thuringiensis var. [subsp.] kurstaki (0.012 B.U.I. per tree) resulted in moderate protection from grazing damage to female flowers and cones. At Aubrey, systemic applications of acephate also reduced damage by spruce budworm larvae and the spruce cone maggot: autumn and early spring applications were equal in efficacy, and the label rate (0.875 g acephate/3.2 cm diameter at breast height) provided similar protection to the half-label dose.