Comparison of Guthion 2L and Guthion 3F for Control of the Sugarcane Borer (SCB), Large-Plot Field Trial, 1982

Foliar spray concentrates of each Guthion formulation were applied from an airplane at 0.83 kg (AI)/ha per application to a field of 1st stubble sugarcane (Var. CP 72-356) at Little Texas plantation near Napoleonville, La., to control season-long SCB infestations. Untreated plots served as checks. A randomized complete block design was used with four replications of each treatment. Individual plots consisted of a single block of sugarcane surrounded by headlands and ditchbanks; plot size ranged from 0.93 to 2.27 ha. Each spray concentrate was applied in water to the crop canopy on 18.3-m swath-widths at a rate of 18.7 liters finished formulation per ha per application. Insecticides were first applied after sugarcane internodes were visible and when 5% of the stalks harbored small (1st to 3rd stage) SCB larvae in leaf sheaths. Applications were repeated when that level of infestation was again found in the Guthion L-treated plots; dates of application were 13 Jul., 11 and 30 Aug. The efficacy of insecticide treatments was evaluated at crop harvest, 28-30 Sep., by comparing the percentages of sugarcane internodes damaged by season-long populations of SCB larvae in treated and untreated plots. Five (10 stalk) samples randomly selected in each plot were scanned for external signs of internode penetration by SCB larvae.