Effects of Water Quality on Insecticide Performance for the Control of Tarnished Plant Bug, Lygus lineolaris, in Cotton.

Insecticide efficacy often varies by location and year. Many factors can influence an insecticide's efficacy, but an often-overlooked factor is the quality of water in a carrier solution. Multiple experiments were conducted to evaluate the impact of water quality on insecticide efficacy. In the first experiment, leaf dip assays were conducted with Transform, Orthene, Bidrin, and Centric, each mixed in three waters with hardness levels of 10.9, 178, and 430 ppm. Transform, Orthene, Bidrin, and Centric were also mixed in three waters having pHs of 6.47, 8.03, or 9.27, with an untreated check. Adult plant bugs were placed on a one-half-inch leaf disc after drying, and mortality was observed at 48 hours. In the second experiment, Transform 1.5 oz/ac, Orthene 0.75 lb/ac, Bidrin 8 oz/ac, and Centric 2 oz/ac were each mixed in three waters with hardness levels of 10.9, 178, and 430 ppm, then applied to cotton for tarnished plant bug control. In the third experiment, Transform 1.5 oz/ac, Orthene 0.75 lb/ac, Bidrin 8 oz/ac, and Centric 2 oz/ac were each mixed in three waters with pHs of 6.47, 8.03, and 9.27, then applied to cotton and evaluated for tarnished plant bug control. In the fourth experiment, Bidrin was mixed with waters with a pH of 6.4 and 9.1. AMS, Quest, Smoke, Diversify, and an experimental compound were each added to water with a pH of 9.1 prior to the addition of Bidrin, then applied to cotton. In the fifth experiment, Bidrin was mixed with water having a hardness of 10.9 ppm (soft water) or 430 ppm (hard water). AMS, Quest, Smoke, Diversify, and an experimental compound were each added to water with a hardness of 430 ppm, Bidrin was then added, and the solutions were then applied to cotton. No differences in treatments were present in the first, second, or third experiments. In the fourth experiment, the experimental compound and Quest provided better control than Smoke at 4 days after treatment (DAT). At 7 DAT, Smoke continued to provide the poorest control. In the fifth experiment, there were no differences at 3 DAT, but at 7 DAT, Diversify provided better control than the soft water. [ABSTRACT FROM AUTHOR]