Adjuvants work by altering the physical characteristics of the constituents of the spray tank and any target surfaces including:

• Spray solutions - to increase wetting and spreading

• Spray Droplets - to maximise retention and avoid run-off

• Leaf Surfaces - to maximise uptake/penetration

Particular adjuvants perform specific functions. To produce an adjuvant which performs all of these tasks will result in an overly compromised product, therefore a range of adjuvants is available.

Water Conditioners

The performance of some agrochemicals and foliar applied fertilisers is impeded when mixed in water which is Alkaline, Hard, Brackish, or contaminated with insoluble deposits. Many farms are forced to use sources of water which are either of high pH (over 7.0) or are ‘hard’, containing significant levels of Calcium, Magnesium or Bicarbonate ions. In such conditions, some expensive agrochemicals and fertilisers are prone to rapid hydrolysis and precipitation resulting in poor performance due to loss of active ingredients particularly when multi-product tank mixing is required.

Spreading Agents

The most basic and traditional wetting agents are based on 90% Nonylphenoxy Polyethyoxy Ethanol. Non-ionic means that there are no positive or negative ions to compete or react with the active chemistry of the product being tank mixed. These products reduce surface tension of the water droplets causing them to flatten or spread on the leaf surface.

Penetrants

Many of the wetter’s will help penetration because their spreading effect increases contact area. But there are also a number of products which specifically aid penetration. Of primary importance are products based on Propionic Acid. These ‘disturb’ the waxy cuticle of the leaf and the epidermal layer, allowing the penetration of systemic agrochemicals and fertilisers.

Stickers

Synthetic Latex (styrene butadiene copolymer) is used as a ‘sticker’ with contact insecticides and fungicides. It enhances activity by reducing spray drift, greater droplet deposition and by physically sticking the contact agrochemical to the leaf surface. This leads to increased penetration and rainfastness.