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Soil Degradation of Two Phenyl Pyridazinone Herbicides

Published online by Cambridge University Press:  12 June 2017

P. R. Rahn
Affiliation:
Weed Res. Lab., Dep. of Bot. and Plant Pathol., Colorado State Univ., Fort Collins, CO. 80521
R. L. Zimdahl
Affiliation:
Weed Res. Lab., Dep. of Bot. and Plant Pathol., Colorado State Univ., Fort Collins, CO. 80521

Abstract

Degradation of SAN 6706 [4-chloro-5-(dimethylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone] and SAN 9789 [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3 (2H)-pyridazinone] was studied in a sandy loam soil at temperatures of 5, 20, and 35 C. After 210 days of incubation 10, 80, and 97% of SAN 6706 had been dissipated from soil at 5, 20, and 35 C., respectively. SAN 6706 was converted to SAN 9789 and a demethylated metabolite in the soil. SAN 9789 was converted to the demethylated metabolite. It was difficult to differentiate between first and second-order kinetics in the degradation of these compounds. SAN 6706, at 20 and 35 C, had a half life of 50 and 9 days respectively, and an Arrhenius activation energy of 15.8 Kcal/mole. SAN 9789, at 20 and 35 C, had a half life of 270 and 70 days, respectively, and an activation energy of 11.8 Kcal/mole. The degradation of SAN 6706 was inhibited by a chloroform treatment, and microbiological degradation is suggested.

Type
Research Article
Copyright
Copyright © 1973 Weed Science Society of America 

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References

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