Influence of Three Drift Control Adjuvants on Volatility, Adherence, and Efficacy of Herbicides

Abstract

Studies were conducted to determine the tolerance of several crops to herbicide sprays containing three spray drift control adjuvants, a cross-linked polyacrylate (Norbak), a pseudo-plastic spray gel agent composed primarily of natural carbohydrates (Dacagin), and hydroxyethylcellulose (Vistik). Other studies were conducted to observe the effect of the adjuvants on the efficacy of 1,1′-dimethyl-4,4′-bipyridinium ion (paraquat) when used with or without a surfactant, the effectiveness of the adjuvants in preventing 3-amino-s-triazole plus ammonium thiocyanate (amitrole-T) from being washed off plants, and the effect of the adjuvants in reducing vapor loss of the ethyl ester of (2,4-dichlorophenoxy) acetic acid (2,4-D) from leaves. Little increased injury was caused from the addition of the adjuvants to herbicides sprayed on several crops. The adjuvants added to paraquat were not effective substitutes for surfactant; however, Dacagin or Vistik added to paraquat combined with surfactant did not reduce the efficacy of paraquat. Norbak reduced the efficacy of paraquat, with or without the addition of surfactant. The adjuvants did not prevent amitrole-T from being washed off plants. Results of vapor studies suggested that Dacagin and Norbak reduced vapor loss of the ethyl ester of 2,4-D from plant surfaces.