Curtis M. Elsik

Glyphosate adjuvant formulation with glycerin.

The development of many crops with glyphosate tolerance has created a large demand for glyphosate herbicide formulations. Commercial aqueous solution glyphosate formulations usually contain a surfactant along with other formulation additives. The surfactant can function to help the spray solution wet the weed surface, and can also help potentiate the active ingredient. The other formulation ingredients usually include materials that function as humectants, antigelling agents, and antifreeze agents. Various traditional petrochemical derivatives have been used to achieve these effects. In this paper glycerin, a renewable natural material provides all of the nonsurfactant excipient properties. The advent of biodiesel production has created a surge in the production of glycerin. It has been found that this crude glycerin can be incorporated into commercial aqueous glyphosate formulations and can replace the traditional petrochemical derivative constituents. The glycerin functions as the humectant, antigelling agent, and antifreeze agent. This paper deals with the modifications and specifications necessary to achieve a suitable finished glyphosate product, as well as the performance results observed from field trials with the final formulation.

Spray Drift Reduction Technology Adjuvant Evaluation

Twelve commercial drift reduction agents were evaluated for their characteristics in the three most commonly accepted parameters for spray droplet size formation—extensional viscosity, dynamic surface tension, and kinematic viscosity. Samples were sprayed in both water and in the presence of a commercial herbicide formulation. The spray droplet spectra for these agents were then determined under rigorous control, in still-air conditions, using a Sympatec HELOS/KF laser diffraction particle size analyzer. Spraying an actual pesticide formulation that contains a wetting agent is important because the surfactant present reduces dynamic surface tension and can significantly reduce spray droplet diameter. The aerosol particle size distributions were measured using an electronic actuator that moved the nozzle spray pattern through the laser in a reproducible manner. There are multiple mechanisms that can influence both volume mean diameter and percent fines below 105 microns. There are natural and synthetic water-soluble polymers that function by increasing extensional viscosity. There are oil products that produce emulsions that keep small spray drops from forming. The droplet spectra for the different commercial products were grouped according to their specific drift reduction mechanism in order to see if a better correlation could be made on how they individually affected the resulting droplet particle size distribution.

Cationic-based Crop Oil Concentrates

For most of six decades, crop oil concentrates (COCs) have been used as important tank mix adjuvants for increased pesticidal penetration. For the past 30 years, cationic surfactants have been known to enhance the bio-efficacy of numerous acid-based herbicides, especially glyphosate. With the advent of glyphosate-tolerant crops, glyphosate has become almost universal in its use. This has led to some issues with weeds hard to control with glyphosate alone. Recently a practice has developed where other herbicides and COC formulations are mixed with glyphosate to address problems with glyphosate-tolerant plants. A field study was conducted to develop a COC containing cationic surfactants that would deliver excellent, stable emulsification of the oil phase and boost the herbicidal activity of both glyphosate and the admixed herbicide. This COC worked very efficiently in a broad range of waters as well as ultra-high electrolyte environments such as ammonium sulfate solutions common to glyphosate applications.