Efficacy of solid formulations of emamectin benzoate at controlling lepidopterous pests

Six solid formulations of emamectin benzoate (three impregnated powder blends, two dry powder blends, and one soluble granule) were compared with an emulsifable concentrate. (EC) formulation for their residual efficacy at killing tobacco budworm, Heliothis virescens (F.) (= Helicoverpa virescens (F.)), and beef armyworm, Spodoptera exigua (Hubner), in glasshouse tests. Two trials were conducted. Emamectin benzoate was applied tu plants at two rates in each trial(8.4 and 0.084 g ai/ha in the first trial; and 8.4 and 0.84 g ai/ha in the second trial). The first trial was conducted in a glasshouse; in the second trial, plants mere treated in the glasshouse and moved outdoors for the duration of the study. In the first trial, all three impregnated powder blends, one dry powder blend, and the EC formulation were comparable in their effectiveness at controlling both targets when applied at the high rate (8.4 g ai/ha). At the low rate, efficacy at controlling H. virescens did not differ among formulations, whereas the two powder formulations provided the longest residual efficacy against S. exigua. In the second trial, one impregnated powder blend, two dry powder blends, a soluble granule, and the EC formulation were comparable in their effectiveness at killing both species up to 10 days after application when applied at the high rate (8.4 g ai/ha). At the low rate (0.84 g ai/ha), one powder formulation was consistently more effective at controlling S. exigua, whereas no formulation consistently outperformed all others at controlling H. virescens. Two field studies demonstrated that two dry powder blend formulations were very effective and comparable to the EC formulation at controlling Helicoverpa zea (Boddie), Keiferia lycopersicella (Walsingham), and S. exigua on tomato. These data demonstrate that solid formulations of emamectin benzoate have potential for control of Lepidoptera. The importance of a solid formulation for emamectin benzoate is discussed.