A Ðeld trial was conducted in 1994 to determine the foliar deposit of tebufenozide (RH5992), applied aerially, and its efficacy against spruce budworm, Choristoneura fumiferana (Clem.). A commercial 240 g litre~1 formulation of the insecticide (Mimic 240LV) was mixed with water, dyed with a tracer dye (Rhodamine WT) and sprayed with a light Ðxed-wing aircraft. Six application strategies were tested. Five used 70 g AI ha~1 in a spray volume of 1 or 2 litre~1 ha~1 with single or double applications ; the sixth was an unsprayed control.
Results show that the spectra of the spray applications were, with one exception, fairly uniform. Volume and number median diameters ranged from 100 to 130 km and 27 to 72 km, respectively. Mean number of drops cm~2 on Kromekote cards were \2É0 for strategies where either 1 or 2 litre ha~1 were sprayed. Nevertheless no one strategy produced droplet densities that were signiÐcantly di †erent (P \ 0É05) from the other strategies. Tebufenozide recovered from foliage averaged 2É5 to 5É9 kg g foliage~1 when 1 litre ha~1 was sprayed and 5É8 to 6É8 kg g foliage~1 after 2 litre ha~1 were sprayed. When a single application was the strategy used, the mean number of droplets cm~2 and kg tebufenozide g foliage~1 ranged from 1É2 to 1É4 and 2É5 to 5É9, respectively. With double applications, the same response parameters ranged from 0É3 to 1É9 and 2É5 to 6É8, respectively. Budworm population reductions (%) and the number of larvae that survived tebufenozide treatments were signiÐcantly di †erent (P \ 0É05) from the controls. After strategies that used 1 litre spray ha~1, mean percentage population reductions ranged from 61É4 to 93É6 whereas populations were reduced by 85É6 to 98É3% when 2 litre ha~1 were sprayed. After double applications the mean percentage population reductions ranged from 93É6 to 98É3, but single application strategies resulted in mean reductions of 61 to 86%. Mean population reductions in the controls were 61%. The mean number of larvae per branch that survived spray strategies of 1 litre ha~1 ranged from 1É3 to 7É4, and from 0É4 to 1É3 when 2 litre ha~1 was the spray volume. In the controls an average of 10É2 larvae survived. With one exception, mean percentage defoliation in the treated areas was also signiÐcantly less (P \ 0É05) than that in the control. Mean defoliation in trees sprayed at 1 litre spray ha~1 ranged from 40 to 62É8% whereas those treated at 2 litre ha~1 had mean defoliation levels from 31É5 to 62É8%. In contrast, average defoliation in the controls was 92É1%. When a single application was the spray strategy, mean defoliation ranged from 31É5 to 62É8%. These data imply that a double application of tebufenozide at 70 g in 2 litre ha~1 was the most efficacious strategy. However, analyses of the data also show that the primary inÑuence on deposits and defoliation was interactions between number of applications and spray. Nevertheless the two independent variables acted without signiÐcant interactions when inÑuencing percentage reductions of spruce budworm populations.
1998 SCI (