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Absorption, Translocation, and Metabolism of Chlorimuron and Nicosulfuron in Imidazolinone-Resistant and -Susceptible Smooth Pigweed (Amaranthus hybridus)
Published online by Cambridge University Press: 12 June 2017
Abstract
The absorption, translocation, and metabolism of the ethyl ester of chlorimuron and nicosulfuron in resistant (R) and susceptible (S) smooth pigweed (Amaranthus hybridus) were investigated. R and S smooth pigweed seedlings (5 to 10 cm tall) were treated with foliar-applied 14C-labeled chlorimuron and nicosulfuron and harvested at 3, 6, 24, and 72 h after application. Chlorimuron absorption increased with time in both populations of smooth pigweed and was higher in the R accession only at 6 h after application. Nicosulfuron absorption did not increase with time in the R accession, and after 6 h, there were no differences between the R and S accessions. Absorbed chlorimuron and nicosulfuron were translocated to shoots and leaves above and below the treated leaf, but not into the roots in both accessions. Translocation of chlorimuron and nicosulfuron out of the treated leaf was also similar in the two accessions. Metabolism of 14C-chlorimuron occurred more rapidly in the R accession with approximately 68% remaining as chlorimuron at 3 h after application. At the same time period, 81% of the absorbed radioactivity remained as chlorimuron in the S accession. Metabolism of 14C-chlorimuron at 24 and 72 h after application was greater in the S than the R accession of smooth pigweed. Metabolism of 14C-nicosulfuron was similar in the two accessions and did not increase with time. Rapid herbicide metabolism may explain the twofold level of crossresistance of the R accession of smooth pigweed to chlorimuron at the whole plant level.
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- Copyright © 1999 by the Weed Science Society of America
Footnotes
Current address of the first author is Novartis Crop Protection, Inc., 4160 Dublin Road, Milliard, OH 43026.
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