Dissipation and potential crop injury for soil applied clomazone, chlorimuron, imazaquin, and imazethapyr
Curran, W.S.
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https://hdl.handle.net/2142/22907
Description
Title
Dissipation and potential crop injury for soil applied clomazone, chlorimuron, imazaquin, and imazethapyr
Author(s)
Curran, W.S.
Issue Date
1990
Doctoral Committee Chair(s)
Liebl, Rex A.
Department of Study
Agronomy
Discipline
Agronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Agronomy
Chemistry, Agricultural
Language
eng
Abstract
Cultural practices such as tillage and method of application can influence herbicide persistence, dissipation processes, and subsequent crop injury. In field studies, the influence of tillage system and herbicide application method on dissipation rate and potential for injury to corn (Zea mays) was investigated. Herbicides evaluated included clomazone (2-((2-chlorophenyl)methyl) -4,4-dimethyl-3-isoxazolidinone), imazaquin (2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl) -3-quinolinecarboxylic acid), imazethapyr (($\pm$)-2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-$ 5$-oxo-1H-imidazol-2-yl) -5-ethyl-3-pyridinecarboxylic acid), and chlorimuron (2-(((((4-chloro-6-methoxy-$ 2$-pyrimidinyl)amino) carbonyl) amino) sulfonyl) benzoic acid). Dissipation rates were monitored using chromatography and bioassay. Laboratory studies were conducted to investigate the contribution of photolysis in the dissipation of imazaquin and imazethapyr on two soil types.
In field experiments, corn displayed some injury at the 3-leaf stage from clomazone, chlorimuron, imazaquin, and imazethapyr carryover, but the only significant influence on grain yield was with chlorimuron on high pH soil. Residues of these herbicides from accurate and uniform preemergence applications to soybeans are not likely to persist and injure corn. Under condition favorable for corn growth, low to moderate levels of corn injury, visible at early vegetative development, may not influence grain yield.
In the tillage and herbicide application study, climatic conditions following application influenced the rate of dissipation. Incorporated applications of clomazone, imazaquin, and imazethapyr persisted longer than preemergence treatments in a low rainfall year. Laboratory assays indicated that tillage prior to herbicide application and four months following application did not influence dissipation rate. However, because of possible herbicide redistribution, subsequent crop injury was greater with imazaquin and imazethapyr and less with clomazone in reduced tillage plots than in conventional tillage treatments.
In the photolysis study, imazaquin and imazethapyr degradation were greatest on moist sand, while photolysis on dry sand and on a silty clay loam soil was minimal. Imazaquin dissipation was rapid on moist sand, with 43% loss in 24 hours. The more rapid photolysis of imazaquin and imazethapyr on coarse textured wet soil was likely due to lower soil adsorptivity and greater availability for photochemical alteration.
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