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Herbicide Adjuvants

  1. Bryan Gerald Young

Published Online: 15 APR 2003

DOI: 10.1002/047126363X.agr007

Encyclopedia of Agrochemicals

Encyclopedia of Agrochemicals

How to Cite

Gerald Young, B. 2003. Herbicide Adjuvants. Encyclopedia of Agrochemicals. .

Author Information

  1. Southern Illinois University, Carbondale, Illinois

Publication History

  1. Published Online: 15 APR 2003


Herbicide adjuvants have been a critical component of successful herbicide applications since the 1950s. An adjuvant is defined as any substance in a herbicide formulation or which may be added to the spray tank to modify herbicidal activity or application characteristics. Adjuvants have several possible functions such as serving as emulsifiers and water conditioners; reducing the surface tension of the spray droplet; and influencing size, leaf retention, contact angle, spreading, and wetting of the spray droplet. All of these characteristics can enhance herbicide uptake through interactions of the adjuvant with plant barriers associated with the leaf surface such as leaf hairs and the cuticle as well as the plasma membrane. The most common families of adjuvants are the surfactants (e.g., nonionic), oil-based adjuvants (e.g., crop oil concentrate), and the inorganic salts (e.g., ammonium sulfate). Selection of the proper adjuvant for use with a specific herbicide can prove difficult due to complex interactions involving the herbicide, adjuvant, target plant species, spray carrier, and environmental conditions. Hence, no single adjuvant will fully optimize the activity of several herbicides on several weed species.


  • absorption, foliar;
  • absorption, herbicide;
  • adjuvant activator;
  • adjuvant modifier;
  • adjuvant utility;
  • ammonium sulfate;
  • critical micelle concentration (CMC);
  • crop oil concentrate;
  • cuticle, plant;
  • cutin;
  • droplet, spray;
  • droplet, contact angle;
  • droplet coverage;
  • droplet deposition;
  • droplet drift;
  • droplet pH;
  • droplet retention;
  • droplet size;
  • droplet spread;
  • droplet surface tension;
  • droplet viscosity;
  • droplet wetting;
  • efficacy, herbicide and adjuvant;
  • emulsifier;
  • ethylene oxide;
  • herbicide contact;
  • herbicide systemic;
  • herbicide uptake;
  • humidity, effects on plant cuticle;
  • hydrophilic;
  • hydrophilic-lipophilic balance (HLB);
  • hydrophobic (lipophilic);
  • inorganic salts;
  • pectin;
  • petroleum oil;
  • plasma membrane, structure and adjuvant interaction;
  • phytobland oils;
  • spray properties, effects of adjuvants on;
  • stomata;
  • surface tension;
  • surface tension dynamic;
  • surface tension equilibrium;
  • surfactant amphoteric;
  • surfactant anionic;
  • surfactant cationic;
  • surfactant definition;
  • surfactant nonionic;
  • surfactant organosilicone;
  • trichomes (leaf hair);
  • vegetable seed oil;
  • volume mean diameter (VMD);
  • water conditioner;
  • hard water;
  • wax, epicuticular