SYMPOSIA PAPER Published: 01 January 1998

Correlation of Adjuvant Physico-Chemical Properties and Glyphosate Efficacy


Greenhouse experiments were conducted to investigate the effect of adjuvants on glyphosate efficacy. Adjuvants evaluated were Silwet L-77, Kinetic, Dyne-Amic, Impact, Induce, Optima, LI-700, Freeway, X-77, and Agri-Dex. Tested two weed species were redroot pigweed (Amaranthus retroflexus L.) and barnyardgrass [Echinochloa crus-galli (L.) Beauv.]. In most cases, glyphosate, at 0.56 kg/ha, combined with adjuvants resulted equal or better control in both weed species. Optima was most effective for enhancing glyphosate efficacy. However, the combination of glyphosate with either Induce or Freeway showed antagonism.

Correlation of adjuvant physico-chemical properties and glyphosate efficacy was also analyzed. The results showed that contact angle and spreading coefficient had significant effect on glyphosate efficacy 1 week after treatment (WAT). As the time interval increased to 2, 3, and 4 WAT, the significance of the correlation decreased.

Author Information

Sun, J
Witco Corporation, Tarrytown, NY
Singh, M
Institute of Food and Agricultural Sciences, Citrus Research and Education Center, University of Florida, Lake Alfred, FL
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Developed by Committee: E35
Pages: 273–280
DOI: 10.1520/STP14170S
ISBN-EB: 978-0-8031-5392-9
ISBN-13: 978-0-8031-2491-2