Biodegradation characteristics of imazaquin and imazethapyr

Journal Article · Wed Nov 01 04:00:00 EST 1989 · Weed Science; (USA)

OSTI ID:5868860

Cantwell, J R; Liebl, R A; Slife, F W

The extent of {sup 14}C-imazaquin and {sup 14}C-imazethapyr abiotic vs biotic degradation in soil was investigated. Degradation was measured in an in vitro system which allowed 90% recovery of applied herbicide. Triallate biodegradation is well documented and therefore used as a standard. Herbicide degradation was compared in two soils, a Cisne silt loam and a Drummer silty clay loam. Herbicide degradation in gamma-irradiated soil was compared to fresh soil. Biomass quantities were measured for the duration of the experiments. {sup 14}CO{sub 2} evolution, extractable parent, metabolites, and unextractable residue were measured. After 12 weeks of incubation, 95% of the radioactivity could be extracted as parent from sterilized soil. In unsterilized soil, imazaquin and imazethapyr degraded at a similar rate which was dependent upon soil type. All herbicides degraded slower in the Drummer soil and triallate degraded two to three times faster than the imidazolinones in either soil. {sup 14}C-imazaquin degradation products included {sup 14}CO{sub 2} and unextractable residues. The major product from {sup 14}C-imazethapyr degradation was {sup 14}CO{sub 2}. Evolution of {sup 14}CO{sub 2} from an imazethapyr-treated Cisne soil, containing a serial dilution of activated charcoal, demonstrated that adsorption of herbicide was negatively correlated with degradation. Therefore imidazolinone microbial degradation is regulated by the amount of herbicide in soil solution as determined by soil characteristics.

• OSTI ID: 5868860
• Journal Information: Weed Science; (USA), Journal Name: Weed Science; (USA) Vol. 37:6; ISSN WEESA; ISSN 0043-1745
• Country of Publication: United States
• Language: English

Related Subjects

550201 -- Biochemistry-- Tracer Techniques
553000* -- Agriculture & Food Technology
59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
BIODEGRADATION
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DECOMPOSITION
HERBICIDES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PESTICIDES
SOILS
TRACER TECHNIQUES