Effect of Adjuvants on Cucumber (Cucumis sativus) Sensitivity to Quizalofop^1,2

Abstract

Cucumber [Cucumis sativusL. ‘Calypso′] susceptibility to the ethyl ester of quizalofop {2-[4-[(6-chloro-2-quinoxyalinyl)oxy] phenoxy] propanoic acid} was investigated under field and greenhouse conditions. Cucumber yield was significantly reduced under field conditions with a single or repeated application of quizalofop at 0.14 or 0.28 kg ai/ha. Under greenhouse conditions, quizalofop significantly suppressed cucumber plant fresh weight with or without the presence of an adjuvant. Enhancement of herbicide activity was related to the concentration of adjuvant. At a higher rate of quizalofop, addition of the lower concentration of an adjuvant increased the herbicidal effect (growth suppression and visually estimated phytotoxicity). At a lower concentration, increasing adjuvant concentration enhanced visually estimated phytotoxicity.

Inhibition of Chloroplast-Mediated Reactions by Quizalofop Herbicide

“…Our results indicate that quizalofop had a direct effect on photophosphorylation in corn chloroplasts in addition to its effects on electron transport. The mechanism of quiz alofop ester inhibition of cucumber growth is yet to be de termined in light of our present results, but effects are localized (21) and concur with findings of physiological effects on grass plants (10).…”

Effects of Additives on the Efficacy, Uptake, and Translocation of the Methyl Ester of Thifensulfuron

“…Surfac tants, used as additives, increased phytotoxicity (6,23) and absorption of 2,4-D [ (2,4-dichlorophenoxy)acetic acid] (14). Benefits of surfactants have also been demonstrated with a number of other herbicides (6,9,10,20,21,22,26).…”