Introduction

51
Adjuvants and Your Herbicide
Adjuvants are important ingredients in chemical weed control. Many herbicides must be applied with an adjuvant. If it is
forgotten, the level of weed control can vary widely, and re-spraying may be necessary.
Many products have adjuvants built into the formulation. Others require adjuvant addition (e.g. Refine SG). Some adjuvants
were developed specifically for one herbicide, and these are either pre-packaged with the herbicide, or are identified by
name on the label (e.g. Turbocharge for Achieve, Amigo for Select/Centurion). Consult a company representative to determine
the support for pesticide adjuvant combinations not listed on the product label.
With some products, adjuvants need to be added only under certain conditions. For example, glyphosate products have
built-in adjuvants, but require additional adjuvant when low rates (pre-seeding or chem-fallow), high water volumes, or
certain tank mixes are used.
Adjuvants should be added only when required. If one is not required, addition can reduce weed control or injure crops.
Product labels will describe when an adjuvant is required, and what type should be used.
There are two main classes of adjuvants: “activators or spray modifiers” (these include surfactants and crop oils), and
“utility modifiers” (these include pH adjusters, water conditioners, low-drift adjuvants, and anti-foaming agents). The most
important class of adjuvants is the activators. Surfactants, the main group within the activators, are “surface active agents.”
These chemicals produce effects at points where two substances touch, such as between two liquids (herbicide and water)
or between a solid and a liquid (herbicide and leaf surface). Some surfactants act as dispersing agents, helping to keep a
pesticide suspended in water. Others work on the plant, improving the wetting, sticking and penetrating characteristics of
the herbicide droplets. Oil-based adjuvants contain petroleum or vegetable oil plus an emulsifier that suspends the oil in
tiny droplets within the spray solution. Oil-based adjuvants typically assist in herbicide penetration into the leaf.
There are two basic type of surfactants (ionic and non-ionic), of which the non-ionic are most common. The following table
list the surfactants registered for use with herbicides in Western Canada.
Weed Control
Adjuvants and Registered Pesticides:
Note – some products are specific about the concentration of active ingredient in the surfactant for product performance.
Check with the product page in this guide or the product label.
Trade Name Composition Registered Pesticides
Addit (PCP#29263) 37% Surfactant blend Bison
Adigor Adjuvant (PCP#28151) 48.8% methylated rapeseed oil 28.2% Broadband
ethoxylated alcohol
Agral 90 (PCP#11809 or 24725), 90% nonylphenoxy polyethoxy ethanol Accent, Altitude FX, Battalion, diquat, Escort,
Agsurf II (PCP#30071)
92% Alcohol ethoxylate
flucarbazone, glyphosate, Muster, Pinnacle,
Prism, imazethpyr, metsulfuron, thifensulfuron/tribenuron,
Reflex, Reward, Triton K,
Ultim
Amigo (PCP#22644),
X-Act (PCP#28225),
Patron Adjuvant (32496)
Assist (PCP#16937),
XA Oil Concentrate (PCP#11769),
Score (PCP#12200),
30% phosphate ester surfactant clethodim † *
83% paraffin based mineral oil 17%
surfactant blend
AAtrex, Basagran (all crops), Blazer,
clodinafop † *, clodinafop + bromoxynil/
MCPA ester † *, Harmony K*, Harmony SG*,
quizalofop (Contender, Yuma GL), Simplicity
(Not all adjuvants may be used with all
herbicides listed)