What are pesticide formulations? What dosage forms are commonly used in forestry?

The original drug of pesticide generally can not be used directly, it must be processed and formulated into various types of formulations, in order to use. Commercial pesticides are in the form of some kind of dosage form, sold to the user. China is currently using the most dosage forms are emulsifiable oil, suspension, wettable powder, powder, granules, water, poison bait, mother liquor, mother powder and more than ten types of dosage forms. Most pesticide dosage forms are formulated to become sprayable before use, or formulated as poison bait for use, but powders, seed coatings, ultra-low-volume sprays, fumigants, etc., can be used directly without formulation. Each pesticide raw material can be processed into several dosage forms. Various dosage forms have certain characteristics and use of technical requirements, should not be arbitrarily changed usage. For example, granules can only be thrown or treatment of soil, and can not add water to spray; wettable powder should only be sprayed with water, can not be directly spray powder; powder can only be directly sprayed or mixed with poisonous soil or seed mixing, it is not appropriate to add water; a variety of rodenticides can only be mixed with grains and other food made of poisonous bait can be applied.

Different dosage forms for the environmental conditions vary, the south of China's humid and high temperature, cold and low temperature in the north, for all types of pesticide dosage form storage is very unfavorable. Wettable powder and spray powder in the case of improper storage of powder agglomeration phenomenon, thus affecting the suspension of powder in water, as well as powder in the air floating ability; emulsion formulations, suspensions and other liquid formulations, in the winter low-temperature storage time is too long, it is easy to layered agglomeration, crystallization and other dosage form destruction phenomenon; some of the emulsion formulations in the high temperature will be gradually evaporated to dissipate the content of emulsified preparations concentration Changes occur, resulting in the precipitation of active ingredients. The name of each preparation is composed of three parts: active ingredient content, pesticide name and dosage form, e.g., 50% ethofumesate emulsifiable concentrate, 5% phorate granules, 15% triadimefon wettable powder, 0.025% dichlorvos sodium salt bait and so on.

Forestry commonly used dosage forms include

(1) powder

Powder

Powder mixture of pesticides and fillers mixed in a certain proportion, after mechanical grinding into a powdery mixture, 98% of which through the 300 (10-15 micron) sieve number of the powder, such as 2.5% trichlorfon powder, etc.. Powder commonly used fillers, such as talc, clay, clay and so on. Pharmaceuticals can only be used as spray powder, poison soil, poison bait, seed mixing and so on. Powder in arid areas or mountainous areas with difficult water sources popular with the masses, because it is easy to use, no water, with a simple powder sprayer can be sprayed directly on the crop, and high efficiency, the adhesion on the crop is small, less residue, not easy to produce drug damage. In addition to the direct use of powder spraying, but also seed mixing, soil treatment, preparation of poisonous bait granules and other prevention and control of disease, insects, grass and rodent pests.

Powder spraying should be carried out in the morning and evening when the crop leaf surface is wet or dew, because the deposition of powder particles on the crop surface mainly by adhesion or electrostatic adsorption, but its adhesion is very small, in the crop surface with a water film, the adhesion of powder particles to improve the ability to improve the effectiveness of prevention.

Disadvantages of powder is the use of particles with a diameter of less than 10 microns, due to the influence of the ground airflow, easy to drift away, wasting the amount of medicine, but also cause environmental pollution, affecting people's health. At the same time, processing, dust, the operator's health impact is greater. But used in greenhouses and greenhouses of the closed environment for spray powder control of pests and diseases, can make full use of the fine powder particles in the air and floating effect of the movement ability, can make the plant leaves in the front, the back of the uniform drug deposition, to improve the prevention and control effect, and will not be outside the shed of the environment caused by pollution. The use of powder is a better method of drug application in greenhouses and greenhouses.

(2) wettable powder

Nowadays, the vast majority of our original drug processing into wettable powder and emulsifiable oil these two types of agents. Wettable powder is based on the development of a powder dosage form, its performance is better than powder. It is a pesticide and inert filler and a certain amount of additives (wet spreading agent, suspension stabilizers, dispersants, etc.) in proportion to the proportion of fully mixed and crushed to reach 98% through the 325 mesh sieve, that is, the average particle size of the drug particles of 3 to 5 microns, the wetting time of less than 1 minute, the suspension rate of more than 80% of the quality of the fine powder standard. When used, add water to form a stable suspension, and use a sprayer to spray. Sprayed on the plant adhesion is good, the efficacy is also better than the powder of the same original drug. WP, if the processing quality is poor, coarse particle size, poor performance of additives, easy to cause the product adhesion, not easy to disperse in water suspension, or plug the nozzle, precipitation and other phenomena in the sprayer, resulting in uneven spraying, easy to make the plant localized pests, especially after a long period of storage of wettable powders, its suspension rate and wettability will decline, so it is best to verify the above two indicators before use before use.

(3) emulsifiable concentrate

In our country is a large amount of a dosage form. Emulsifiable concentrate is the proportion of pesticides dissolved in organic solvents (toluene, xylene, etc.), adding a certain amount of pesticide-specific emulsifiers formulated into a transparent homogeneous liquid. The content of active ingredients is high, generally in 40% to 50%. Emulsion oil is easy to use, diluted with water to a certain proportion of the emulsion can be used. The emulsifier contained in the emulsion oil, is conducive to the droplets in crops, insects and germs on the adhesion and spreading. Application and deposition effect is relatively good, long duration of efficacy, good efficacy. In addition to spraying with a sprayer, emulsifiable concentrate can also be applied to the stem, irrigation of the heart and leaves, seed mixing, seed dipping and so on. When using emulsifiable concentrate, it should be noted that because emulsifiable concentrate contains organic solvents, it has the effect of promoting the penetration of pesticides into the epidermis of plants and the skin of animals, and it should be applied according to the concentration of use specified in the instructions for use. The residual time of the emulsifiable concentrate is long, especially when applied to vegetables and fruit trees, it is necessary to strictly control the amount of time of application to avoid the occurrence of drug damage and poisoning accidents.

(4) granules

Adsorbed by the carrier of the original drug by a certain proportion of a certain fineness of the granular material. At present, granules have become one of the most important pesticide formulations. Japan began in 1958, used to process 2,4-drop, and later developed to sodium pentachlorophenate and hexachlorophenol; since 1965 and successive development of the granular formulations of the pesticides such as grass withered ether, kill grass, diazinon and isoinoceramid. Characteristics of granules granules have: ① will not drift, can be accurately spread on the target; ② use no dust flying; ③ do not need to be formulated into a liquid or the use of special spraying equipment, can be used by hand to spread directly. Therefore, it is a kind of energy-saving, labor-saving ideal agent.

(5) thick emulsion

Also known as emulsion-type suspension or water emulsion. This preparation does not contain organic solvents, non-flammable, good safety, no organic solvent-induced harm, irritation and toxicity. Concentrated emulsion is liquid or mixed with solvents made of liquid pesticides to tiny droplets dispersed in water and water as the medium of the preparation, the manufacture of more than emulsifiable oils, wettable powders are difficult, high cost, a number of developed countries from the point of view of the safe use of pesticides in this area of work in the first place, our country is still in the beginning of the research stage.

(6) smoke agent

is the original pesticide and fuel (sawdust, charcoal powder, coal dust) and oxidizing agents (ammonium nitrate, potassium nitrate, etc.) and deflagration agent (ammonium chloride, ammonium sulphate, terra cotta, talcum powder), were first ground, and then mixed in a certain proportion of homogeneous made of powdered preparations, and at the same time, with the wick lit, so that the pesticides sublimate into a smoky form. This type of pesticide is mainly used in forests, greenhouses and greenhouses plant pests and diseases, as well as warehouse pest control.

While the efficacy of fumigants is high, they can also cause damage when used incorrectly. Preparation of the smoke agent must fully understand the nature of pesticides and can be analyzed to determine the smoke agent into the smoke, otherwise the decomposition of pesticides loss is very large. In addition, the fumigant should also pay attention to the method of point release. The correct method should first be prepared into a certain shape of the agent, or in a suitable container, such as paper fuming cans. Leave a smoke hole in the top of the can, fill the smoke agent in the can, and when it is lit, the smoke is rapidly ejected from the top hole, and all of it is shot into the air. This use can avoid the smoke is adsorbed by the ground, and can promote the rapid spread of smoke. Also, the smoke agent into a piece or block is also a very convenient way to use, but do not use the smoke piece or smoke block directly on the ground, should be placed on the top of the smoke piece of a wire bracket, about 30 centimeters from the ground. In this way, the smoke can be completely dispersed into the air, and further diffusion of diffusion. Use of the smoke method should grasp the law of air movement. In the ground temperature is higher than the air temperature will produce updrafts. Clear daytime sunlight to the ground, so that the ground temperature increases, so the daytime updraft is very significant, especially at noon. In the evening, when the ground is no longer illuminated by sunlight, the ground begins to exotherm, and the heat released is absorbed by the upper air, so the phenomenon of the ground temperature being lower than the temperature of the upper air occurs, i.e., the phenomenon of "inversion". The phenomenon of updraft disappears in the range of the "inversion layer". At this time to apply smoke, smoke can form a more stable "smoke cloud", covering the ground, the effect is better. Therefore, applying smoke in the evening can avoid the interference of updrafts. When the crop canopy grows densely, forming a "canopy", combined with the phenomenon of inverse temperature, you can often get a good effect of smoke. When smoke is applied at this time, the smoke cloud will submerge the entire canopy and last for a period of time. In the high degree of depression in the forest, orchards and the growth of taller and plant canopy closed field crops, to take the smoke method will achieve significant control results.