Evaluation of Selected Insecticides For Rice Water Weevil Control, 1996

Abstract

Abstract Several insecticides applied at various rates, formulations, and times were evaluated for control of adult rice water weevil at the Rice Research Station, Crowley, LA. Plots, 5 X 25 ft, were arranged in a RB design with 4 blocks and 11 treatments with sub-sample nesting within the block X treatment effect. Fertilizer was pre-plant incorporated at 45 lb (23-12-12) N-P-K/acre and applied broadcast 4 and 6 wk post-flood at 45 lb (23-12-12) and 55 lb (21-0-0) N-P-K/acre respectively. Plots were drill-seeded with ‘Cyprus’ rice at 90 lb of seed/acre to Crowley silt loam on 2 May, flushed on 21 May and permanently flooded 28 May. The her-bicides Basagran, Stam, Arrosolo, and Ordram were applied to control weeds. Basagran and Stam were applied at 0.5 and 4.0 lb(AI)/acre on 27 May. Arrosolo and Ordram were applied aerially at 3.5 lb(AI)/acre on 4 Jun and 3.0 lb(AI)/acre on 11 Jun, respectively. All pesticide applications except Furadan 3G were made using a CO2 backpack sprayer delivering 15 gpa at 28 psi with 110015VS flat-fan nozzles on a 3 ft boom. Three randomly selected soil samples per plot were taken 11,18 and 26 Jun using a 4 X 4 inch core sampler. Individual samples were washed through a funnel, fitted with wire screen, into a 35 mesh screen sieve. Collected rice water weevil (RWW) larvae and pupae were floated in a saturated NaCl solution, and counted. Plots were harvested on 11 Sep using a Kubota combine. Moisture content of harvested grain was determined and standardized to 12% moisture for determination of yield. Rice water weevil larval data were log transformed to improve normality before being subjected to analysis of variance. The experimental and sam-pling error terms for the RWW larval data were tested for homogeneity of variances, and pooled error terms were used to test the treatment effect when appropriate. Treatment means were separated using protected least significant difference (LSD) at P = 0.05.