Home > Knowledge > Content
Types of formulation
Aug 09, 2018

Formulations are either wet or dry. Wet formulations will be expressed as concentration of active ingredient per litre. Dry formulations as concentration of active ingredient per kilogram. The type of wet or dry formulation is often incorporated at the end of the product name as an abbreviation, e.g. Talstar 100 EC (emulsifiable concentrate), Bistar 80 SC (suspension concentrate), Spraytop 250 SL (soluble concentrate), Copper Oxychloride WP (wettable powder),Logran 750 WG (water dispersible granules).These abbreviations for the type of formulation are known as formulation codes and are standardised by the APvMA. Dusts (DU) Also like wettable powders, dusts are very fine particles of clay (or talc or chalk) to which an active ingredient has been added. But dusts are applied dry. They are still formulated for ready-touse home garden products like rotenone (Derris vegetable Dust) and are popular for urban pest control for termites and ants – the insects track the dust back to the nest and spread it through the nest giving very good control. Pellets (PE) Pellets are like granules but are mixed as a slurry or thick liquid which is then extruded under pressure like a long sausage and cut into a uniform shape, e.g. snail pellets and mouse baits.

Dry formulations

Wettable powders (WP) 

Wettable powders are usually fine mineral clays to which an active ingredient has been added. They are diluted with water to form a suspension. The solid powder particles are not dissolved in the liquid but dispersed through the liquid. They require agitation to remain dispersed. Outside home garden products, wettable powders are becoming less common these days, except for fungicides like copper which are difficult to formulate otherwise. Wettable powders fell out of favour because they are difficult to mix, difficult to keep suspended, clog filters and increase nozzle wear.

Water dispersible granules (WG) 

Instead of a fine powder, these are formulated as granules. Like wettable powders, they form a suspension and require constant agitation. Many herbicides are formulated as water dispersible granules. Water dispersible granules have gained in popularity as their packaging does not pose the same environmental problem as liquid formulations whose containers have to be specially rinsed and recycled. Water dispersible granules often contain high proportions of the active ingredient, up to 90%. While it is possible to put water dispersible granules in water soluble packaging, this has not been adopted much in Australia. Water soluble packaging is a de-facto closed transfer system, as the product itself does not have to be handled by the applicator. An example of such a product is the forestry herbicide Eucmix Preplant (terbacil plus sulfometuronmethyl).

Dusts (DU) 

Also like wettable powders, dusts are very fine particles of clay (or talc or chalk) to which an active ingredient has been added. But dusts are applied dry. They are still formulated for ready-touse home garden products like rotenone (Derris vegetable Dust) and are popular for urban pest control for termites and ants – the insects track the dust back to the nest and spread it through the nest giving very good control.

Pellets (PE) 

Pellets are like granules but are mixed as a slurry or thick liquid which is then extruded under pressure like a long sausage and cut into a uniform shape, e.g. snail pellets and mouse baits.

Granules (GR)

Granules are applied dry and consist of an active ingredient in clay. They are applied to soil where they are incorporated (or mixed in) and work by breaking down in the soil in response to soil moisture, e.g. aldicarb (Temik) which is used to control soil pests like nematodes.

Tablets (TA) 

Tablets are similar to granules in that they consist of an active ingredient with a dry inert. The most common agricultural tablets are phosphine tablets, used for grain fumigation and rabbit control. On exposure to air, the phosphine tablets absorb moisture and break down to give off phosphine gas, a very toxic fumigant at extremely low concentrations.

Baits (BA) 

These are reserved for control of vertebrate pests, rodents and molluscs. Shelf stable baits, e.g. Foxoff, a protein cube that is attractive to the pest and which contains a vertebrate pest poison to control the pest – in this case 1080. Other baits are prepared just before use, e.g. chicken wings injected with 1080 for fox control or carrots injected with RhDv (rabbit haemorrhagic disease or calici virus) for rabbit control.

Wet formulations

Emulsifiable concentrates (EC)

Emulsifiable concentrates consist of an oil-soluble active ingredient in a solvent (neither of which is soluble in water) with an emulsifying agent. They are diluted with water, the droplets of the concentrate being dispersed through the solution. The emulsifying agent keeps the oil droplets suspended in the water rather than separating out and forming a layer on top, like petrol on water. Emulsifiable concentrates have a milky appearance and require agitation. They are a very popular formulation, especially for insecticides, despite their increased dermal toxicity and flammability risks. Organic solvents and hydrocarbons carry an increased risk of phytotoxicity or crop damage and can also damage rubber and plastic components in spray equipment.

Suspension concentrates (SC) 

Suspension concentrates are essentially a water dispersible granule in a pre-mix. Fine granules (1-3 microns) are suspended in water, to be further diluted in the spray tank. Another very popular formulation, used for most types of pesticide.

Soluble concentrates (SL) 

Soluble concentrates are true solutions where the concentrate is fully dissolved when mixed with water, i.e. they cannot be mechanically separated. They do not require agitation. Examples include paraquat (Gramoxone), 2,4-D amine and most glyphosate herbicides.

Microencapsulates (ME) 

Microencapsulates are essentially a granule in a plastic or starch coating, usually in a pre-mix where they are suspended in water. Once diluted and sprayed out, the capsule provides a slow release of the active ingredient, e.g. Penncap-M (microencapsulated parathion).

Ultra low volume (ULV) 

ULv solutions consist of the active ingredient in a small amount of organic solvent. ULvs are exclusively insecticides. They are not diluted and are specifically designed for aerial application, although it is common now to add a mineral oil and/or some water to reduce the risk of drift.

Gels (GE) 

Gels are essentially intensified emulsifiable concentrates in a semi-liquid or gel form that come in their own ready-to-use dispenser packs and do not require mixing or diluting, e.g. picloram (vigilant) which is suitable for small scale control of woody weeds.

Aerosol dispensers (AE) 

Aerosol dispensers contain small amounts of the active ingredient with a propellant under pressure, ready-to-use. The liquid drops are delivered to the target in a mist of very small particles. They are mostly used for domestic control of nuisance insects like flies and mosquitoes. Some aerosol dispensers put out a foam, like shaving cream, e.g. glyphosate.

Previous: What are Fungicides

Next: Adjuvants