1 preface
The quality of pesticide formulation and preparation is the key factor to determine the value and effect of pesticide products, as well as the safety of production and users and the impact on the ecological environment. Using different kinds of synergistic additives, a kind of original drug is processed into products with different dosage forms and specifications, which produces different effects, even great differences. In recent decades, various field efficacy results show that the penetration of pesticide preparation products processed at present is low. After spraying in the field, more than 95% pesticides can't work, and ineffective pesticides are lost and volatilized, which pollutes the atmosphere, soil, water quality and even the whole ecological environment. The current countermeasures: (1) compound, that is, mixing two or more pesticides to make preparations, can improve the toxicity of pesticides and reduce the drug resistance of pests, but pests will produce compound drug resistance, and at the same time, the types of pollutants in the environment will increase. (2) Adding synergist can greatly reduce the dosage of pesticide active ingredients, give full play to the efficacy, and reduce the probability of insect resistance as much as possible. And promote crop growth and development, enhance stress resistance, increase production and income.
Synergists are mainly inhibitors of biodegradable enzymes such as multifunctional oxidase and carboxylesterase in pests. The mechanism of pesticide synergist is mainly to inhibit or weaken the detoxification of targets (pests, weeds, germs, etc.). ) on the activity of pesticides, delaying the metabolic rate of pesticides in the control object, thus increasing the biological control effect. As a pesticide adjuvant, pesticide synergist has different effects on different kinds of pesticides. The chemical structure of synergist must adapt to the mode of action of active ingredients;
(1) Internal absorbents (bactericides, herbicides, pesticides): auxiliaries are needed to help transfer the active ingredients in plants. For foliar treatment agents, this also includes the transfer of drugs through plant epidermis.
(2) Contact killing/protective agents (fungicides and pesticides): auxiliaries are needed to help increase coverage (wetting agents) and enhance washability (adhesives).
The synergist itself has no activity, but after being mixed with the corresponding pesticides, it can obviously improve its wetting, spreading, dispersion, retention and permeability, reduce the spraying liquid from drifting with the wind (airflow), and prevent or alleviate the damage to adjacent sensitive crops. It is beneficial to spreading and adhering the liquid medicine on the leaves, reducing the decomposition of effective components in pesticide preparations by ultraviolet rays, and achieving the purposes of prolonging the effective period of drug efficacy, improving its biological activity, reducing the dosage, reducing the cost and protecting the ecological environment. A good synergist can not only improve the control effect of pesticides by several times or even dozens of times, but also delay the emergence of drug resistance and prolong the life of hard-won pesticide varieties.
2 Overview of foreign countries
Since the discovery in the late 1930s that the compound with o-methylenedioxyphenyl, called MDP compound for short, has more or less synergistic effect not only on pyrethroids, but also on other pesticides, many foreign professional pesticide companies and research institutions have been actively developing pesticide synergists, published many patents and articles, and put many new products on the market.
2. 1 pesticide aspect
Application targets include pyrethrins, organochlorine, organophosphorus, carbamate and rotenone from botanical insecticide.
Methylene dioxbenzene derivatives are mainly used as pesticide synergists such as pyrethroids, carbamates, organophosphorus and insect growth regulators, and the general formula is as follows:
Dipropyl ether, piperonyl butyl ether, methyl synergistic phosphorus, synergistic phosphorus, XG- 1 hypertonic oil synergist,
HWP-2 powerful synergist, GY- 1 pesticide synergist, azone, penetrant CN, Jing 4-9 synergist, etc. The synergistic effect of mixed fatty alcohol polyoxyethylene ether additive developed by shenyang institute of chemical technology in 1983 on atrazine was nearly doubled. On this basis, we are actively developing the synthesis of pesticide synergist SYP-2 and its analogues to enhance the activity of pesticides, aphids and acaricides, and have made some progress. The synergist and the main agent have been mixed and sprayed in barrels or applied as a composition of preparations, which has a good application prospect.
3. 1 pesticide aspect
The application targets are: fenvalerate, permethrin, 234 bio-bacterial ester, cypermethrin, cyfluthrin, deltamethrin, fenvalerate, pyrethroid, carbamate, allethrin, organophosphorus pesticide, etc.
Triphenylphosphine: a special synergist for malathion.
GY- 1 pesticide synergist: used in emulsifiable concentrate and methomyl aqueous solution of beta-cypermethrin, beta-cypermethrin, iverdin and omethoate.
Agricultural hyperosmotic synergist: Jing 5, used for pyrethroid pesticides, such as diphacinone, kungfu, cypermethrin and fenvalerate; Jing -4 is used for other pesticides such as carbamate and endosulfan and other pesticides compounded with organophosphorus, and for some organophosphorus pesticides such as dimethoate and monocrotophos.
Penetrant CN: it has synergistic effect (times) on most pyrethroid pesticides and nearly $ NUMBER times on organophosphorus pesticides, such as deltamethrin, pyrethroid, monocrotophos, isocarbophos, methyl parathion, omethoate and dichlorvos.
CT-90 1: Used for avermectin, acetamiprid, imidacloprid, methyl parathion, isocarbophos, dichlorvos, etc.
HP- 1: used to oxidize dimethoate and acaricidal scales, improving the efficacy (#6 times.
Piperonyl butyl ether: cypermethrin, cyfluthrin, deltamethrin, fenvalerate, fenthion, dichlorvos, atrazine and triclosan.
Synergistic phosphorus: when mixed with organophosphorus (especially pyrethroids) and other pesticides, it has obvious synergistic effect on a variety of pests, and its control synergistic activity on related pests that have developed resistance is also obvious.
Octachlorodiether: Synergistic effect of fenpropathrin, ethofenprox, cypermethrin and Es- biothrin in mosquito control.
Azone (dodecyl azetidine -2- one): It has obvious synergistic effect on pyrethroids, organophosphorus and other pesticides.
3.2 Herbicide
The application objects are organophosphorus, diphenyl ether, amide and so on.
Azone: It has synergistic effect on a variety of pesticides, such as herbicides, such as Najing, Huwei, Butachlor, acetochlor, etc. , all have obvious synergy.
The trade name is 96 1, which is a special synergist for glyphosate.
4 Application prospect
At present, in the face of increasing population, decreasing land, increasing food demand and increasingly severe environmental requirements, people need to develop more efficient and safe new pesticides. However, new pesticides have long research and development cycle, large investment, high risk and low success rate, especially modern high-efficiency and ultra-high-efficiency pesticides. With the rapid development of pesticide synergist, many new dosage forms will inevitably be produced: on the one hand, it can reduce the environmental pollution caused by old dosage forms such as large tonnage wettable powder and emulsifiable concentrate in China, adjust the present situation of serious unreasonable dosage form structure in China, and save packaging, storage and transportation costs, which has remarkable economic and social benefits for improving drug efficacy, reducing toxicity and reducing environmental pollution; On the other hand, it can improve the physical properties of the original drug, not only prolong the service life of the original drug, but also give full play to the role of the original drug, reduce the dosage, expand the scope of application, reduce the cost and save manpower. But also can achieve the purposes of reducing environmental pollution, improving the safety of users and maximizing the efficacy of effective components of pesticides.
Therefore, it is of great practical significance to research and develop synergists suitable for China's national conditions and international market demand, endow various pesticides with surface activity, and increase their physical and chemical properties such as wettability, permeability, film forming and adhesion.
Main points of using pesticide additives
Auxiliary substances used to improve the physical and chemical properties of pesticides during processing or use, also known as pesticide additives. Pesticide additives are the general name of all kinds of additives except effective ingredients in chemical pesticide processing dosage forms Adjuvant itself has basically no biological activity, but it can enhance the control effect. There are many kinds of pesticides with different physical and chemical properties and different processing requirements for dosage forms, so the additives needed are also different. Whether the adjuvant is properly selected has a great influence on the efficacy of pesticide preparations. For example, the mixed EC containing 10% chlorpyrifos and 30% diesel oil is similar to the 20% chlorpyrifos EC without diesel oil, but the dosage of chlorpyrifos is different by 1 times. When using Bordeaux mixture, if 0.2%~0.3% bone glue is added, it can resist rain erosion and improve the disease prevention effect. The rational use of pesticide additives can often improve the safety of pesticides to plants and reduce the toxicity to people and animals. According to the information published by the International Federation of Pesticide Manufacturers' Associations (GIFAP), there are currently 62 dosage forms. The main auxiliaries involved in the formulation of the dosage form are: dispersant, wetting agent, emulsifier, synergist, penetrant, spreading agent, adhesive, stabilizer, thickener, film former, anticoagulant, anti-caking agent, disintegrant, defoamer, anti-drift agent, antistatic agent, phytotoxicity reducing agent, herbicide and antidote of propellant, etc.
First, the use of additives.
1. Application of pesticide adjuvant surfactant
Surfactants can make pesticide preparations that cannot be directly used into usable pesticide preparations. As a pesticide adjuvant, it can not only improve the use effect of pesticides, but also reduce the dosage of pesticides, reduce the impact of pesticides on the environment and bring great benefits to agricultural production. At present, surfactants used in pesticides mainly include fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, sulfonate, sulfonate, amide, silicone and so on. For example, a nonionic surfactant combined with 20% chlorimuron-ethyl can effectively control marijuana. Adding appropriate higher aliphatic hydrocarbons to glyphosate can greatly improve its weeding effect.
In recent years, the development of biosurfactant has also made rapid progress, and it will also be a pesticide adjuvant with great development prospects. Biosurfactants are a kind of biological compounds with surface activity produced by microorganisms. Biosurfactants not only have the physical and chemical characteristics of chemically synthesized surfactants, but also have the advantages of non-toxicity and biodegradability, and have a very broad application prospect, and may become substitutes or upgraded products of chemically synthesized surfactants.
2. Oil and grease additives
Oil additives can accelerate the absorption efficiency of foliar spraying pesticides, and they can form a uniform and stable emulsion with pesticides and water, which is helpful for target crops to absorb pesticides when foliar spraying. Three kinds of weeds in lawn were controlled by commercial petroleum lubricating oil additives and emulsifiers. The wax on the surface of target crops can be dissolved in petroleum lubricating oil solution, and its solubility varies with crop species and growing environment.
Vegetable oil additives are much better than petroleum lubricating oil and nonionic surfactants in strengthening the biological activity of herbicides and reducing droplet drift. For example, the mixture of dimethoxydine and methylated oil additive Scoil has better control effect on three kinds of weeds than petroleum lubricating oil additive CleanCrop. Vegetable oil additives can promote absorption and conduction, and enhance the control effect of herbicides on weeds. Experiments show that plant fatty acids are stronger than glycerides. Chester. Foy et al. pointed out that the control effects of several additives to increase nicosulfuron on Setaria viridis were as follows: methylated sunflower oil >; Petroleum lubricating oil > nonionic surfactant WK> nonionic surfactant X-77.
3. Inorganic salts Some inorganic salt additives mixed with surfactants can greatly improve the activity of herbicides. These inorganic salts include ammonium sulfate (NH4)2SO4, diammonium hydrogen phosphate (NH4)2HPO4 and magnesium sulfate MgSO4. However, some salts will destroy some herbicides when sprayed. According to some data, except calcium sulfate CaSO4, sodium sulfate Na2SO4, calcium phosphate Ca3(PO4)2 and sodium phosphate Na3PO4, calcium, magnesium, sodium and potassium iron salts will destroy 2,4-D, but this antagonism can be reduced by lowering the pH value of the solution or transforming 2,4-D into a salt that is difficult to dissociate. Urea, ammonium nitrate, ammonium polyphosphate, ammonium sulfate, petroleum lubricating oil and nonionic surfactant are mixed with gaicaoling and dimethoxydine respectively to control Setaria viridis in cereal crops. Petroleum lubricating oil is larger than surfactant or salt.
4. Mixed use of pesticide additives
In practical application, not only a single adjuvant is used. In order to improve the efficacy, a variety of additives can be selected at the same time, but attention must be paid to overcoming the interaction between various additives to prevent the photodegradation of pesticides and reduce the efficacy. If various auxiliaries (liquid ammonia, fertilizer, oil, solvent and surfactant) are mixed, the activity of tribenuron-methyl in wheat and rye fields can be enhanced, the penetration of effective components can be enhanced, and it can be promoted to enter plant tissues. Therefore, in order to give full play to the efficacy of pesticides, various additives must be used reasonably. Under the same dosage form, different kinds of additives will obviously affect the performance of the drug. If pesticides are incompatible with surfactants, the suspension rate of suspending agent will decrease, and inappropriate wetting and dispersing agents will decrease the suspension rate of wettable powder. Surfactants will also affect the foliar absorption of pesticides, which is particularly important in the treatment of pesticides with stems and leaves.
Second, the factors affecting the application of pesticide additives
Surfactants are composed of hydrophilic and hydrophobic parts, and the ability to reduce surface tension depends on the correlation between hydrophilicity and hydrophobicity and the distribution of molecules between different phases (droplets and plant or animal surfaces). The wetting and spreading performance of drugs on the target and the retention on the target surface directly affect the penetration and biological activity of drugs on the target surface, so the addition of surfactants can enhance the spreading of drug molecules on the leaves or insects, thus promoting the absorption of drugs. This effect is also related to the temperature, concentration and atmospheric pressure of the solution.
1. Effects of structure, polarity and concentration of surfactants on absorption When studying the effects of nonionic surfactants on adsorption and permeation of 2,4-D leaves, SyuanTan et al. found that polyoxyethylene glycol (PEG) series surfactants can greatly improve the permeation effect of some pesticide sprays on the epidermis of apple paraxial leaves, but the adsorption effect is not obvious. Hydrophilic-lipophilic balance value (HLB) of PEG surfactant is negatively correlated with the adsorption amount of surfactant and the permeation amount of 2,4-D in leaf epidermis. Adding surfactant can improve the permeability of 2,4-D to stratum corneum membrane, and its permeability decreases with the increase of HLB value of surfactant. Therefore, the change of HLB value of surfactant is an important factor affecting the permeability of 2,4-D.
2. Complex solute permeation
In the process of evaporation, the amount of substances (components) penetrating into the epidermis has nothing to do with the total amount of solution. The absorption of solute is related to the coefficient and concentration between epidermis and residue, and the permeation rate depends on the affinity of solute and surfactant. The permeation rate of compounds is not only related to the solubility in epidermal wax, but also related to the evaporation rate of solvents. After evaporation, the permeation rate of the compound will be affected by the concentration in the cutin wax layer and epidermis. Surfactants may have the functions of dredging transportation obstacles, hindering the dispersion of compounds, transferring their absorption sites, changing the properties of compounds and reducing their resistance, thus creating conditions for plants to inhale active compounds. The improvement of permeability is based on the physical and chemical interaction (combined with dissolution or osmotic mechanism) between the effective components of drugs and surfactants when they penetrate into leaves or the change of transport obstacles in plants induced by special surfactants, so that they can penetrate particles more easily.
Third, the role of pesticide additives in pesticides
The development, popularization and application of new pesticide application technology are often inseparable from supporting additives. Additives are often needed in order to obtain better efficacy or control the harm to a minimum.
1. Some pesticides must use adjuvants at the same time to ensure their efficacy. Such as glyphosate, regulating phosphine, 2-4 drops of amine salt, thatch, dicamba, picloram, etc. In the application process, specified auxiliaries (mainly wetting agents, penetrating agents and sometimes safety agents) must be used.
2. Choosing a suitable adjuvant can obviously improve the curative effect, and the effect is too poor without adjuvant. If pesticide developer TritonCST is added to pesticide malathion spray solution (concentration 0. 1%), the effect of killing melanodermatitis can reach 83%~93% in 72 hours (6% when malathion is used alone). Another example is that when the concentration of additives Nong Ru 100, Tween 80 and penetrant Tx is 0. 1%, it has obvious influence on regulating phosphine and inhibiting the growth of kidney beans.
3. Matching additives can meet the special performance requirements of some application technologies, making them practical advanced technologies. For example, ultra-low volume spraying technology has special requirements for preparation carriers or diluents and phytotoxicity reducing agents; Foaming spraying method has special requirements for foaming agent and foam stabilizer; Controlled release technology has special consideration for capsule skin and suspension additives; Electrostatic spraying technology needs to meet the requirements of ultra-low capacity and has a proprietary anti-static system; The combined application of pesticide and liquid fertilizer is a time-saving and economical technology, which requires the preparation to have good compatibility or use special additives.
4. In order to ensure safety, additives are needed in the application. For example, adding proper anti-transpiration agent and anti-drift agent can reduce the harm of air drift to sensitive crops, people and livestock during pesticide application. Add special odorous antifeedant additives and special pigments to warn people to avoid eating by mistake or poisoning; There are still many herbicides with high activity but insufficient selectivity; In order to protect crops from phytotoxicity, safeners (also known as antidotes) are often used in combination with them.
Fourth, the development trend of pesticide additives
Pesticide formulations are developing in the direction of water-based, granulation, multifunction, slow release, labor-saving and refinement. Some new formulations with high efficiency, safety, economy and good environmental compatibility, such as microemulsion, emulsion in water, suspension emulsion, water dispersible granule, dry suspension and sustained-release agent, are constantly emerging, which will be the mainstream of pesticide formulation development in 2 1 century. Around the development trend of pesticide formulations, the world's pesticide additives are developing in the direction of large molecular weight, high efficiency, low dosage, multifunction, high quality and low price. According to this development trend, combined with the actual situation in China, relevant experts put forward the following suggestions. First, we should focus on the development of lignin sulfonate, naphthalene sulfonate and alkyl naphthalene sulfonate formaldehyde condensate products. Second, we should speed up the development of three-dimensional structure of large molecular weight surfactants. Third, vigorously develop new film-forming products of seed coating agent. Fourth, actively develop pesticide adhesives, stabilizers, high-efficiency dispersants and herbicide antidotes, and increase new varieties of synergists and penetrants. At the same time, we should explore the application of microcomputer in the production of pesticide additives and the development of new products, and the development of new pesticide additives by computer-aided design is under way. The research of pesticide processing industry in China is relatively weak. It is suggested that qualified scientific research institutes, research institutes and enterprises establish databases to promote the application and popularization of microcomputers in this field.