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Metabolism of Herbicides

  1. Robert E. Hoagland,
  2. Robert M. Zablotowicz

Published Online: 15 APR 2003

DOI: 10.1002/047126363X.agr162

Encyclopedia of Agrochemicals

Encyclopedia of Agrochemicals

How to Cite

Hoagland, R. E. and Zablotowicz, R. M. 2003. Metabolism of Herbicides. Encyclopedia of Agrochemicals. .

Author Information

  1. USDA, ARS, SWSRU, Stoneville, Mississippi

Publication History

  1. Published Online: 15 APR 2003


Herbicide metabolism in plants and microorganisms is a major factor in the dissipation of these compounds in the environment. Metabolic degradation of herbicides by plant enzymes is the main mechanism of plant resistance to such phytotoxic chemicals. Alternatively, some plant enzymes can metabolize certain nonphytotoxic chemicals (termed proherbicides) to yield active herbicides within the plant. Generally, metabolism of pesticides can be categorized into three separate phases: phase I (enzymatic conversion of a herbicide to a less active compound), phase II (enzymatic conjugation of the parent compound or metabolites generated from phase I), and phase III (conversion of phase II metabolites into secondary conjugates of bound residues). These categories are discussed generally and specifically using typical herbicides as examples. The metabolic divergences and similarities of plant and microbial metabolism are discussed in general, and selected compounds from various herbicide families are used to illustrate metabolic routes of herbicides in plants and microorganisms.


  • acetanilide herbicide;
  • aryl acylamidase;
  • bioengineered herbicide resistance;
  • bioherbicide;
  • bioremediation;
  • biotransformation;
  • bound herbicide residue;
  • carbamate herbicide;
  • carbon-phosphorus bond herbicide;
  • chlorohydrolase;
  • cometabolism;
  • conjugation;
  • dealkylation;
  • dehalogenase;
  • detoxification;
  • dinitroaniline herbicide;
  • diphenylether herbicide;
  • enzyme;
  • enzyme action;
  • esterase;
  • evolved metabolically based herbicide resistance in weeds;
  • glutathione conjugation;
  • glutathione transferase;
  • herbicide class;
  • herbicide family;
  • herbicide metabolite;
  • herbicide safener;
  • herbicide synergist;
  • hydrolytic enzyme;
  • hydrolysis;
  • malonyl conjugation;
  • microbial metabolism;
  • mineralization;
  • mono-oxygenase;
  • naturally occurring phytotoxin;
  • nitrile herbicide;
  • oxidative enzyme;
  • oxygenase;
  • phenoxyacetic acid herbicide;
  • phenylurea herbicide;
  • plant metabolism;
  • proherbicide;
  • sulfonylurea herbicide;
  • thiocarbamate herbicide;
  • triazine herbicide;
  • xenobiotic metabolism