Adjuvants

An overview of the adjuvants in use in Region 8

Adjuvants

Any material added to a pesticide mixture to modify its behavior; includes wetting agents, spreader stickers, other surfactants, penetrants, and drift control agents.

Adjuvants – some definitions

Polar vs. non-polar

• Polar compounds are compounds which have, due to their structure, have a definite imbalance in charge – resulting in a positive and a negatively charged end
• Non-polar compounds are compounds which have evenly distributed charge throughout their molecules
• Polarity in a chemical aids in spreading the chemical over a polar surface or in penetrating one

Polar

Non-Polar

Ionic vs. non-ionic

• In solution ionic molecules separate into positively and negatively charged subparts (ions) while non-ionic molecules do not
• Ions from an ionic compound can interfere with the activity of a polar or an ionic pesticide while non-ionic compounds do not

Ions from an ionic compound

Non-ionic molecule

Adjuvants

Surfactant Any material added to a pesticide formulation which is designed to modify the surface characteristics of the target organism.

Wetting Agent

Any material added to a pesticide mixture which serves to make the surface "wetter" so as to allow more rapid spread of the pesticide on the target – often called a ‘spreader’.

Without wetting agent	With a wetting agent

Penetrant Any material which modifies the target surface in a way which allows more rapid penetration of the surface of the organism by the pesticidal formulation. Products designed to create invert emulsions (oil in water).	Mineral Oil
Napthenic oil	Napthenic oil
Vegetable oil	Vegetable oil
Organic silicone

Spreader

Any material added to a pesticide formulation which improves the formulations ability to rapidly form a film on the target surface – generally interchanged with “wetting agent”.

Sticker

Any material added to a formulated pesticide which improves the ability of the pesticide to adhere to the target surface.

Drift Control Agent

Materials added to a mixture to increase the size of droplets and decrease the tendency of the pesticide to drift off-target.

Pattern indicators

Materials added to a formulation which marks a treated stem so that later identification of those treated vs. not treated is simplified. Dyes in either amine or ester formulations are the most common pattern indicators.

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