Adjuvant Guide

An adjuvant is a chemical designed to improve the activity of pesticides and over come the factors which limit pesticide performance. The official definition is “a material added to a tank mix to aid or modify the action of an agrochemical or the physical characteristics of the mixture”. The activity of an adjuvant can either enhance the biological efficacy of the pesticide or modify the physical characteristics of the spray solution.

Why do we need adjuvants?

The application of crop protection products is a highly inefficient process. It is estimated that only around 15% of applied pesticide reaches its target and that as little as 0.1% reaches its site of action. This means that 85% of pesticide misses the target, going into the environment as spray drift, leaching into the soil or into ground water. This leads to higher costs to the farmer, potential damage to the environment, a poor public image and an increasing likelihood of a pesticide tax. Farmers today are under pressure to produce crops cost-effectively but with the environment very much in mind. They need to justify each input.

Farmers are looking for ways to apply lower spray volumes per unit area in the most cost-effective way. From a practical view point with the limited number of spray days available, they may also be unable to apply the products under the most optimal conditions.

The use of adjuvants is growing because they are often the best way to reduce pesticide dose rates, to increase efficacy, particularly under difficult conditions, and to minimise adverse environmental impact.

Sound development, field trials and marketing have ensured that adjuvants have come of age and are recognised as playing an important role in optimising the performance of crop protection chemicals.

How can adjuvants help the end-user?

enhancing biological performance of the active ingredient

improving the speed of action and target spectrum

aiding coverage, penetration and uptake into the plant

improving rainfastness, particularly in showery weather

reducing or eliminating variables of spray performance such as dry or cold conditions

extending the spray window or increasing the size of target controlled

buffering the spray solution for optimum availability

helping to reduce costs through better performance

improving crop safety

How can they help the environment?

improving the performance of reduced rates and so reducing overall pesticide loading

having an intrinsically low biological activity

reducing drift and loss of pesticide to soil, minimising impact on non-targets and soil organisms

help to reduce leaching of pesticides in the soil environment

managing potential liability situations

Why aren’t adjuvants already in the formulation?

This is one of the most common questions regarding the necessity and use of adjuvants and can be emphatically answered by the following reasons:

Unlike most pesticides that depend on an active ingredient rate per hectare basis, most adjuvants work on a dilution ratio or volume/volume ratio. This means that the correct amount of “adjuvant” can never be predetermined by the pesticide manufacturer since the spray volume may vary from 1 litre per hectare to over 14,000 l/ha!

Adjuvants ‘built in’ to the final pesticide formulations would add significant costs to the product’s manufacturer which would affect ALL end-users, and not just those end-users who simply require the use of a specific adjuvant for a specific job.

Adding adjuvants to the final pesticide formulation will also increase the final volume of the end product. This may result in higher dose rates, larger container sizes, increase freight and storage costs and more handling problems.

Today’s trend is for manufacturers to maximise their returns by producing highly concentrated, low rate of use pesticide formulations. This precludes the addition of an “adjuvant package” in the final formulation (for instance in SU’s).

Many pesticide manufacturers (especially generics) are generally basic in active ingredient production, but NOT in adjuvant production. The final formulation is therefore not fully optimised and requires an additional adjuvant.

A number of pesticide manufacturers (in order to improve operator safety and reduce container waste) are now producing granular formulations. These may be packaged in water soluble bags. Such formulations preclude the addition of oil based adjuvants and other adjuvant technologies (for instance in SU’s).

Regarding storage stability, it is difficult to formulate all the required components of adjuvants in a given pesticide formulation. Some components can degrade certain pesticide active ingredients or even degrade themselves over a prolonged storage period.

Different types of crops may require different types of adjuvant. Certain crops are sensitive to oils, some are difficult to wet. A pesticide manufacturer would not want to build in “adjuvants” that limit a given pesticide to be applied only to one crop.

Ultimately a pesticide manufacturer’s core business is generally the discovery, synthesis, manufacture, sales and marketing of pesticide active ingredients NOT adjuvants. It is well known that certain adjuvants can help specific pesticides to perform at the lowest recommended rate, or even below recommended label rates. Clearly therefore, pesticide manufacturers are NOT economically driven to formulate “adjuvants” into the final pesticide formulation which will lead to the manufacturer ultimately selling LESS of their core products.