Mechanistic Aspects and Effects of Selected Tank-Mix Partners on Herbicidal Activity of a Novel Fatty Acid Ester

Abstract

Only a limited number of contact herbicides exist in agricultural production. Although systemic herbicides are also more efficient for suboptimum spray coverage with long-lasting weed control, contact herbicides provide several advantages. For example, there is no translocation to fruits, roots, and other crop parts and neither have residual activity nor minor risk for spray drift damage. Synthetic products in their use often imply toxicological or other drawbacks. Whereas, natural fatty acids, particularly pelargonic acid (PA), have contact activity and are safer for home and garden use. We recently described a methyl capped polyethylene glycol ester of pelargonic acid (PA-MPEG) as a novel contact herbicide. Both PA-MPEG and PA are applied at high rates per hectare to achieve excellent weed control. We herein report about potential additives to increase PA-MPEG efficacy. Herbicidal active, 1-decanol, and the non-phytotoxic alkylated seed oil-based adjuvant, Hasten™, improved performance by achieving better results than the PA benchmark. Both PA-MPEG and PA appear to mainly act by the disintegration of bio-membranes besides having effects on transpiration. The main suggested effect is desiccation due to cutting the water continuum at the site of evaporation in the intercellular spaces. The synergistic action of the adjuvant Hasten™ and its practical uses are also discussed.