Agriculture adjuvants are one member in the pesticide products. It is used together with pesticides in certain conditions and improves the effects of pesticides. When mixed with pesticides raw materials in the production process or mixed with pesticides, these substances can improve the physical and chemical properties, improve the pesticide effects and become easy to use. They are grouped as pesticide additives or agriculture adjuvants. In general, pesticide adjuvants have no biological activity, but the selection of agriculture adjuvants will impact much on the efficiency of pesticide formulations.
The smooth surfaces of many fungi, plants, and insects make the penetration of pesticide spray solution not easy. To solve this, adjuvants have been used together with pesticide solutions. Adjuvants can help improve the function of pesticides if used suitably. Adjuvants can be any additive that is added to a spray tank that strengthens pesticide performance. For example, adjuvants can be spread stickers, surfactants, buttering agents, crop oils, compatibility agents, and anti-foaming materials. Surfactants are adjuvants that stimulate the dispersing, emulsifying, dispersing, wetting or spreading of the pesticide solution on the plants. Most pesticides need to be used together with adjuvant. If adjuvants are not added to insecticides herbicides or fungicides, pest control can only be reached less than 50%. Adjuvants can help improve the efficiency of pesticides and the right use of adjuvants on plants is very critical.
The types of agriculture adjuvant
There are various types of agriculture adjuvants. According to statistics, there are over 3000 types of agriculture adjuvants all over the world and 200 types of them are used often. The agriculture adjuvant can be grouped by using the method, function, surface activity, structure, molecular size, etc.
(Diagram 1) Different Agriculture Adjuvant
1. Sorted by Function
The agriculture adjuvants added in the production process of pesticides are called formulation additives. As formulation additives, agriculture adjuvants are added to pesticide formulation in the production process, and this can meet the requirement of physical and chemical stability of pesticide formulation as well as meet the requirement of commercial performance. As per the function and effect in the formulation, the adjuvants can be grouped into a diluent, solvent, dispersant, wetting agent, filler and/or carrier, emulsifier, spreading agent, penetrant, controlled release agent, Defoamer, warning pigment, dustproof agent, stabilizer, foaming agent, thickener and thixotropic agent, etc.
When the agriculture adjuvants are mixed with the finished pesticides products, they are called pray additives or tank-mix additives: spray additives refer to additives that are added to pesticide spray directly and this can help improve the utilization rate of pesticides, the performance of pesticide spray, as well as the control effect of plant diseases. There are agriculture adjuvants with properties such as absorption promotion, sedimentation promotion, anti-drift, anti-evaporation, and rain wash resistance, as well as synergists, water quality regulators, and phytotoxicity-reducing agents. The most regular additives are mineral oil-based and vegetable oil-based synergists or silicon adjuvants, surfactants, liquid fertilizers, and polymer additives that help increase the rain wash resistance, wetting, and spreading of pesticides.
2. Sorted by whether it has surface activity
Since most pesticides cannot be soluble in water, different types of surfactants are added to pesticides to meet the water dispersibility and process performance requirement. Thus, agriculture adjuvants are divided into two categories: surfactants (natural or synthetic) and non-surfactants.
Surfactants can be divided into ionic surfactants and nonionic surfactants according to the structure of hydrophilic groups. Ionic surfactant molecules can ionize in water and get positively charged, negatively charged, or both positively and negatively charged ions. Positively charged ions are called cationic surfactants. And its main types are quaternary ammonium salt-type surfactants and amine salt-type surfactants. Negatively charged ions are called anionic surfactants. Its main types are sulfonates, higher fatty acid salts, phosphate, etc.
Ions with both negative and positive charges are called amphoteric surfactants. Betaine-type Amino acid type, and imidazoline type, amine oxide surfactants are the main types. Non-ionic surfactant molecules cannot ionize in water and are neutral in electrical. The main types are polyethylene glycol type and polyol type.
Non-surfactant agriculture adjuvants mainly refer to the inert substances that are added into pesticide formulation, such as fillers, solvents, and other substances which can improve the physical and chemical properties or stability of the pesticide formulation. Nonsurfactant agriculture adjuvants include fillers, carriers, fillers, or adsorbents like kaolin, white carbon black, inorganic salts, clay, urea, sawdust, starch, etc.; solvents and co-solvents such as ethers, alcohols, vegetable oils or hydrocarbons; PH regulators such as sodium carbonate, sodium tripolyphosphate, and citric acid; Warning pigments such as rose essence, brilliant blue, and acid red.
3. Sorted by molecular weight
Surfactants can be grouped into two types: polymer type and ordinary type as per molecular weight. Ordinary surfactants have a molecular weight from several hundred to several thousand. Polymer-type surfactants have a molecular weight from several thousand to several tens of thousands. Polymer-type surfactants can be grouped into three categories: synthetic, semi-synthetic, natural, semi-synthetic, and synthetic as per their sources. Synthetic polymers have types like polyvinylpyrrolidone, acrylic polymers, polyvinyl ether, polyvinyl alcohol (PVA), polyacrylamide, etc. Semi-synthetic surfactants include carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), and cationic starch; Natural polymer surfactants are mainly pectin, starch, protein, and alginic acid (sodium), etc.
How do agriculture adjuvants work for plants?
By understanding how water works, we can know better how agriculture adjuvants work. The molecule of water is bipolar, and it has a positive charge and a negative charge. The negative charge and positive charge will attract each other like a magnet.
Compared with the internal water molecules, the surface molecular of water is more attracted together. This cohesion leads to surface tension and makes the substance resistant to tensile force. And surface tension will prevent things from getting wet. But the agriculture adjuvants or surfactants can break the surface tension. The surface tension is reduced by agriculture adjuvants from two aspects. The first is to increase the unbalancing of surface molecules, and the second is to decrease the attraction among surface molecules, thus the tightness of the surface is reduced.
(Diagram 2) Surface tension is broken by surfactant molecule
The agriculture adjuvants molecule help reduce the surface tension and make pesticides more spread on the plant surface and reach the target. When different substances get in contact with water molecules, different results will happen. If the two substances are different in charge, the two forces will hold together with each other. If the two substances are the same in charge, the two forces will repel. If the two substances don’t have a charge, nothing will happen. Due to the surface tension, water will drop on most surfaces of plants. But this surface tension can be adjusted by the agriculture adjuvants of pesticides.
When the pesticide solution with agriculture adjuvant has lower surface tension, the pesticide will have better spread on the leaves and the effect of pesticides will be improved. Meanwhile, it can decrease the using number of pesticides, reduce the effect of pesticides on the environment, and bring benefits to the agriculture industry. But the pesticides are very special, so it should be careful in choosing the agricultural adjuvants. The synergistic effect of agriculture adjuvants on pesticides is a show of its effectiveness on target organisms. Agriculture can help the distribution and cohesion of pesticides on the surface of organisms better. It can also strengthen the absorption of pesticides by organisms of plants, and thereby improve the biological activity of pesticides
Different agriculture adjuvants have their function. Some adjuvants help in diluting the original pesticide; some help in preventing the beads from gathering and becoming larger; some can improve the wetting, adhesion, and penetrating of the particles. In summary, the main function of agriculture adjuvants is to improve the chemical and physical properties of pesticides and to maximize their effects with the safe application. Agriculture adjuvants are developed along with the development of pesticides. More types and series of agriculture adjuvants are innovated to meet the requirements of different pesticide products. Professional formulation and processing technique is also developed to meet the farmers’ requirements.
Which brands of agriculture adjuvants are popular in the market for plants?
Among different agriculture adjuvants, wetting adjuvants are one of the popular types that are used together with pesticides. Agriculture wetting agents can make insoluble pesticides diluted in water and make them have the wetting ability. It can help decrease the surface tension of water and make the substrate wet. And the pesticide with wetting adjuvants can be well spread on the surface of insects, crops, and weeds. Thus, the removal effect can be improved, and fewer pesticides can be used.
(Diagram 3) A wetting agent with different effects
Following are some popular wetting adjuvant types and their brand names
1. Pull open powder BX
This wetting agent is an old well-known brand. It is one type of sodium salt of butyl naphthalene sulfonate. Its water solubility is good and has very less bubbles. But the problem is that the original powder of BX is very difficult to get and the sold products are not original mostly. Also, the price varies due to the different content of BX. The Nepal BX Dry sold by BASF is one of the open powder series, which has good effects as well as a higher cost.
2.K12, K14 (Sodium Lauryl Sulfate)
K12, and K14 isotherm common wetting adjuvants. It has a very good effect and is white. But when it is exposed to acid, it is easy to decompose. And there will be bubbles occur which are not easy to eliminate. And its cost is also low among the wetting adjuvants.
3.Akzo Nobel’s Morwet EFW
Akzo Nobel’s Morwet EFW is one type of wetting adjuvant with excellent performance. It is a mixture of an anionic wetting agent and alkyl naphthalene sulfonate. The typical property is that it has excellent water solubility as well as very low bubbles. In WDG, Morwet EFW is a good combination with dispersant D-425 for dispersing and wetting.
4. Rhodia’s Global BC/10
Rhodia’s wetting adjuvant is a liquid type of wetting agent and it works very well in the pesticide formulation.
5. Hanmok’s W－2001
Beijing Hanmok’s wetting adjuvant is fine for wax particles. Its solubility in water is normal but its cost is also not very high. WDG is a good combination with dispersants D-1001 and D-1002 for dispersing and wetting.
6.Momentive Silwet 408
Momentive Silwet 408 is used on large scale together with the pesticide in the spray. The wetting ability is a very excellent and reasonable cost. Similar silicone adjuvant from China also performs well and at better prices.
Benefits of agriculture adjuvants for plants
Some types of pesticides must be used together with supporting additives to ensure their effects. For example, dicamba and glyphosate must be used along with designated supporting agriculture adjuvant.
The application of appropriate agriculture adjuvants can improve the effects greatly. For example, if the insecticide malathion spray is added with the pesticide spreading agent Triton CST (0.1% concentration), and the effect of killing black beetles in 72 hours can reach 83-93% (but in single-uses of malathion, it can only reach 6%.
Supporting adjuvants need to meet the special requirements of certain application technologies, which can make them effective in the application. For example, ultra-low volume spray technology has requirements for diluents or formulation carriers or phytotoxicity reducing agents; the foaming spray method has special requirements for foam stabilizers or foaming agents; electrostatic spray technology has requirements not only for ultra-low capacity but also needs special antistatic agent system.
To keep safety, different agriculture adjuvants are needed in some pesticide applications. For example, the anti-drift agent can prevent neighboring sensitive crops, animals, and humans from poisoning by pesticide drifting. The addition of warning colors can also help warn people to keep away from poisoning or accidental ingestion. The herbicide is very active, but its selectivity is not sufficient. To protect the crop from phytotoxicity, herbicide needs to be used together with safe additives. The wetting agent is helping to improve the effects of pesticides, with a better spreading and penetration of pesticides on the surface of different plants and crops. Different kinds of agriculture also help the agriculture industry get a better environment for nearby plants, animals, and humans, especially the green agriculture adjuvants developed along with technological improvement.