Effects of Adjuvants on the Efficacy of the Insecticide (Spinetoram 120 SC) Against Strepsicrates semicanella in Eucalyptus Plantation

Spinetoram 120 SC is an insecticide used against the leafroller, Strepsicrates semicanella (Lepidoptera: Torticidae), in Eucalyptus plantations. Control efficacy in plantations is a difficult issue due in large part to weather. Adjuvants are added to reduce insecticide runoff from the leaf surface. Three adjuvants such as alkyl aryl polyglycol ether 400 g/L (Agristick), mixture of fatty alkyl sulphate and fatty alkyl betaine (CBA Stick 100), and condensate nonylphenolethylene oxide 95 g/L and polyvinyl alcohol 19 g/L (Indostick 100/20 SL) were tested with the insecticide spinetoram 120 SC against S. semicanella. Adjuvant treatments significantly increased the efficacy of spinetoram 120 SC in controlling S. semicanella. The CBA Stick with 3 and 2 ml L⁻¹ reduced S. semicanella incidence best compared to the other treatments at 7 DAT (days after treatment) and 14 DAT. A rain simulation (10 mm) conducted at 30-min intervals after spraying was sufficient to show deterioration in insecticide efficacy. Spinetoram at a dosage of 0.5 ml L⁻¹ with the adjuvant CBA Stick at a dosage of 3 ml L⁻¹ was recorded as the best treatment for S. semicanella at 14 DAT in a simulated rain of 10 mm.