E.G. Kettela

SERG Project # 1995/07 (1998)


Executive Summary

Spray trials of ForayŽ 96B, a high potency aqueous formulation of B.t. var. kurstaki (B.t.k.), were conducted against eastern spruce budworm, Choristoneura fumiferana Clem., on white spruce, Picea glauca Moench (Voss), in Balsam Lake Provincial Park in southern Ontario on 20 May, 1998. Objectives were to generate registration efficacy data, protect trees from a high infestation and appraise its use in an early intervention strategy. Three 40-ha spray blocks and two control blocks were established within the park boundaries. Prespray populations prior to treatment were very high and ranged from a low of 19.1 larvae per branch in Control 1 to 61.8 in Rep. 1 of block BLP-3. At this time, larvae were predominantly in the fourth (30%) and fifth instar (70%) stages. The final postspray measurements showed a significant reduction in budworm survival in both BLP-1 and BLP-2. BLP-3, which was located on the upwind edge, had a lower population reduction. Budworm survival in the three spray blocks was substantially lower than in the unsprayed control. White spruce foliage protection was high in all three blocks, but the highest levels of protection were in BLP-1 and BLP-2, which also had the highest spray deposits. ForayŽ 96B at 30 BIU is thus a potent spruce budworm insecticide that will fit well into an early intervention strategy and it is recommended that registration for this product be pursued.