PROGRESS AND DEVELOPMENTS IN ADJUVANT USE SINCE 1989 IN THE USA

Over 50 articles on adjuvants have been published in Weed Science and Weed Technology, journals of the Weed Science Society of America (WSSA), from July 1989 through September 1992. More than 30 presentations on adjuvants were made at the 1990, '91 and '92 Annual Meetings of WSSA. Research involved c. 45 herbicides, 31 weed species, 19 crops, and numerous adjuvants. Results obtained indicated that the adjuvants tested either enhanced or had no effect on herbicide efficacy. Efficacy was enhanced in the majority of the studies. Some herbicides at lower rates plus adjuvants provided weed control equal to that achieved with higher rates of the same herbicides. Absorption, penetration, and translocation of several herbicides were enhanced with adjuvants. Some adjuvants also enhanced rates of herbicide photolysis, decreased antagonism, prevented herbicide injury to crops, altered the pH of spray solutions, increased deposition and enhanced retention of herbicides, increased rainfastness, promoted better germination of mycoherbicide spores, and were effective formulating agents. Adjuvants appeared to have no effect on herbicides in soil. Product labels of 19 agrochemical companies, involving c. 485 formulations of crop protection chemicals for use in 1992, recommend use of adjuvants with 49 % of such formulations; 5 % specify that no additional adjuvants are recommended, while the remaining 46 % (including granular formulations) do not mention adjuvant use. Adjuvants are recommended with 71 % (and not recommended with only 3 %) of herbicide (including defoliant) formulations, and recommended with c. 30 % and not recommended with c. 14 % of the other classes of crop protection chemicals including plant growth regulators, insecticides, miticides, nematicides, fungicides, larvacides, seed treatments, soil fumigants, and repellents. More than 30 types of adjuvant are mentioned on product labels. Several new adjuvants for use with agrochemicals were marketed during 1990-92.