Agriculture adjuvants is one member in the pesticide products. It is used together with pesticides in certain condition and improves the effects of pesticides. When mixed with pesticides raw material 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 pesticides 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 solution. Adjuvants can help improve the function of pesticide if used in a suitable way. Adjuvants can be any additive that is added into a spray tank which 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 into insecticides herbicides,or fungicides, the pest control can only be reached less than 50%. Adjuvants can help imrpove the effciency of pesticds and the right use of adjuvant 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 method, function, surface activity, structure, and molecular size etc.
(Diagram 1) Different Agriculture Adjuvant
1.Sorted by Function
The agriculture adjuvants added in the production process of pestcides are called formulation additives. As formulation additives, agriculture adjuvants are added into pesticides 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: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 refers to additives that are added in to pesticides spray directly and this can help improving the utilization rate of pesticides, the performance of pesticides 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, 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 increasing 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 in to pesticides to meet the water dispersibility and process performance requirement. Thus, the 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 and 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 can not 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. Non surfacant agriculture adjuvants includes fillers, carriers, fillers or adsorbents like kaolin, white carbon black, inorganic salts, clay,urea, sawdust, and 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 has a molecular weight from several hundred to several thousand. Polymer type sufactants has a molecular weight from several thousands to several tens of thousands. Polymer type surfactants can be grouped into three categories: synthetic, semi-synthetic and natural, semi-synthetic and synthetic as per their sources. Synthetic polymers have types like polyvinylpyrrolidone, acrylic polymers, polyvinyl ether, polyvinyl alcohol (PVA), and 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 does agriculture adjuvants work for plants?
By understanding how water works, we can know better how agriculture adjuvants works.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 magnet.
Comparing with the internal water molecules, the surface molecular of water is more attracted together. This cohesion leads to surface tension and make substance be resistant to tensile force. And surface tension will prevent things from getting wet. But the agriculture adjuvants or surfactants can break surface tension.The surface tension are 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 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 substance are different in charges, the two forces will hold together with each other. If the two substances are same in charges, the two forces will repel. If the two substances don’t have 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 amount of pesticides, reduce the affect of pesticides on environment, and bring benefits to the agriculture industry. But due to the pesticides are very special, so it should be careful in choosing the agriculture 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 be 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 own 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 is to maximize its effects with safe application. Agriculture adjuvants are developed along with the pesticides development. More types and series of agriculture adjuvants are innovated to meet the requirements of different pesticides 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 agent can make insoluble pesticides diluted in water and make it have 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 less pesticides can be used.
(Diagram 3)Wetting agent with different effects
Following are some popular wetting adjuvants types and their brand names
1.Pull open powder BX
This wetting agent is an old wellknow brand. It is one type of the 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 prie varies much due to different content of BX. The Nekal BX Dry sold by BASF is one of the open powder series,which has good effects as well as higher cost.
2.K12, K14 (Sodium Lauryl Sulfate)
K12,K14 is another common wetting adjuvant. It has very good effect and white color. 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 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 good ombination with dispersant D-425 for dispersing and wetting.
4.Rhodia’s Igebal BC/10
Rhodia’s wettingadjuvant is liquid type wetting agent and it works very well in pesticide formulation.
Beijing Hanmok’s wetting adjuvant is fine wax particles. Its solubility in water is normal but its cost is also not very high. In WDG, is good combination with dispersant D-1001 and D-1002 for dispersing and wetting.
6.Momentive Silwet 408
Momentive Silwet 408 is used in large scale together with pesticide in spray. The wetting ability is very excellent and reasonable cost. Similar sillicone adjuvant from China also perform well and with better price.
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 use of malathion, it can only reach 6%.
Supporting adjuvants need to meet the special requirements of certain application technologies, which can make it be effective in the application. For example, ultra-low volume spray technology has requirement on diluents or formulation carriers or phytotoxicity reducing agents; foaming spray method has special requirement for foam stabilizers or foaming agents; electrostatic spray technology has requirements not only on ultra-low capacity, but also needs special antistatic agent system.
To keep safety, different agriculture adjuvants are needed in some pesticides application. For example, anti-drift agent can prevent the neighboring sensitive crops, animals and humans from poisoning of pesticides drifting.The adding 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 the safe additives. The wetting agent is helping improving 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 enviroement to nearby plants, animals and humans, especially the green agriculture adjuvants developped along with the technology improvement.