scope:

ABSTRACT

The aim of this work was to analyze the effect of spray solutions containing new formulations of 2,4-D choline salt (Enlist^TM with Colex-D^TM and Enlist Duo^TM with Colex-D) on the droplet spectra and drift potential generated by flat-fan nozzles. The experimental design included comparisons between solutions with a single herbicide in it: 2,4-D dimethylamine salt (DMA^TM 806 BR) and 2,4-D choline salt (Enlist with Colex-D). We also compared the premix of 2,4-D choline salt and glyphosate dimethylamine salt (Enlist Duo Colex-D) with tank mixtures of the 2,4-D dimethylamine salt with three different formulations of glyphosate (Glizmax^® Prime, Roundup Transorb R, and Zapp QI). Labeled rates of the herbicides were diluted to 80 L ha^-1 and sprayed with flat-fan nozzles at 2.8 bar (Teejet XR11002 and AIXR11002). The volume median diameter and the percentage of droplets smaller than 105 lm (V105) were obtained using an online particle-size analysis system. The drift index was calculated based on data collected in a wind tunnel at a wind speed of 2.5 m s^-1. The amount of drift deposited on nylon strings at 2 m downwind from the nozzle was converted to a percentage of the total volume of spray solution sprayed on each replication. The results showed that the new formulation of 2,4-D choline salt engineered for drift reduction (Enlist Colex-D) provided lower drift potential based on both the droplet spectra and the wind tunnel data compared to the standard 2,4-D dimethylamine salt. The same result was found when comparing the premix of 2,4-D choline salt and glyphosate dimethylamine salt with tank mixtures of 2,4-D dimethylamine salt with glyphosate, regardless of whether glyphosate formulation was part of the tank mixture.