The Use of Bio-Based Surfactants to Enhance the Efficacy of Potash as a Contact Herbicide.
Dylan Walker, Donald Mullins, Richard Fell, and James Westwood. Virginia Tech Univ, 1315 University City Blvd, #2, Blacksburg, VA 24061
In Mali West African potash is a product extracted from wood ash used in food preparation and has recently been identified as an effective contact herbicide. Aqueous solutions of potash are effective in killing plants when sprayed onto leaf surfaces. However, their effectiveness may vary due to poor adherence on vertical, pubescent or waxy leaf surfaces. This study examined whether the addition of bio-based surfactants can enhance effectiveness of potash solutions by increasing their ability to spread uniformly over or adhere to leaf surfaces. The surfactant properties of small aliquots of soap and peanut oil were evaluated by addition to potash solutions, measuring the droplet diameters resulting after application to waxy and pubescent leaves. In addition, adhesion of these formulations to leaf surfaces was measured using solutions containing dyes, which allowed for quantification of their relative retention rates. After application of dye -containing sprays, the adhering solutions were rinsed from leaf surfaces and quantified using a spectrophotometric assay procedure. Results from these studies indicate that the addition of small quantities of soap and peanut oil to potash solutions enhance both their spreading and adhesive properties on leaf surfaces. The use of soap and peanut oil as adjuvants may provide a practical means for Malian farmers to increase the effectiveness of potash solutions as an herbicide.