Basic principles of scientific use of pesticides
From the development process of pest control, the emergence of synthetic organic pesticides is a great progress in the history of pest control, and it is the inevitable outcome of human beings seeking to control harmful organisms and develop plant protection science and technology; everything is one point. For the second, pesticides have both a beneficial side for humans and a disadvantage for humans.
For a long time, people have relied on a large number of pesticides to control harmful organisms, and they have also produced a series of new problems that cannot be ignored. The first is resistant pest populations grow exponentially, so that some prevention and treatment effect of pesticides is greatly reduced, resulting in invalid. The second is the chemical pesticides in killing pests, also killing a large number of non-control object, especially for the development of pest control action from predators, destruction of the ecological balance, resulting in a further increase in pest rampant. The third ecological environment and agricultural products that pollute the atmosphere, waters and soils, especially some pesticides, are potentially carcinogenic, teratogenic and catastrophic, threatening people's health. The fourth uncontrolled abuse of chemical pesticides also affects the survival of beekeeping, sericulture, fisheries and the survival of wildlife resources. Therefore, we must vigorously promote scientific medicine, it is necessary to give full play to the role of major chemical pesticides, but also put its negative role reduced to a minimum as much as possible.
1. Prohibition of high-toxicity and high-residue pesticides: organochlorine pesticides such as DDT and BHC are highly persistent in the environment, and are easy to concentrate through the food chain, enriched in food, and harmful to human health, most of which are non-selective. the broad spectrum insecticide, strong on the day of lethal enemy. Organic mercury preparations such as Sai Li San and Xi Li Sheng are highly toxic to mammals and susceptible to phytotoxicity to plants. Countries in the world have gradually phased out these two types of pesticides. At the same time, countries are also banned from using long-acting pesticides and highly toxic pesticides on crops such as grains, vegetables, tobacco, fruits and medicines as well as near waters. Highly toxic pesticides such as phorate and carbofuran are used only for the treatment of seeds, or in the soil with granules, and not for spraying, to ensure the safety of the application . On the basis of understanding the dynamics of pesticides on crops, the number of days from the last application of crops to crops is also specified to avoid poisoning of humans and animals.
Second, strictly in accordance with the prevention and treatment indicators: due to the comprehensive effects of various factors in the farmland ecosystem, the number of pests is always kept within a certain range, always fluctuating at a certain level, neither increasing without limit We will not go down without limit reduction. If the number of pests is kept in a low-density range, it will not cause economic losses, but also benefit the reproduction of natural enemies, making it a powerful factor in controlling pests, which is very beneficial to human beings . Therefore, we must strictly follow the prevention and control indicators formulated by local governments. Only when the number of pests is close to the level of economic damage, we must take chemical control measures to control them. It is necessary to strive to achieve the rule of treatment that can be ruled; to be able to cure the disease, not to rule, to reduce the area of ​​application and the number of applications. In this way, on the one hand, it can save pesticides, reduce costs, reduce the pollution of pesticides to the environment and agricultural products, and at the same time, expand the protective surface of natural enemies and reduce the killing effect on natural enemies.
Third, master the appropriate period of application: the purpose of determining the appropriate period of application is to obtain the maximum economic benefits of prevention and control with a small amount of pesticides. Generally consider three aspects. The first step is to understand the biological characteristics, characteristics and occurrence of the target, and to find the most vulnerable period. In general, the pests are weak in resistance at the young age, and some pests are clustered at an early stage. Many drill-bit pests and underground pests have to start dip and enter the soil at a certain age, and the effect is obvious. For diseases, it is generally necessary to apply the drug at the early stage of the disease, because once the bacteria invade the plant, the agent is more difficult to function. For weeds, it is best to apply the weeds in the most sensitive period of herbicides, usually in the weed seedling stage ; sometimes in order to avoid harming the crops, it is often done before sowing or before germination. The second is to apply the drug at the most vulnerable stage of the crop. Thirdly, according to the dynamics of the pests and beneficial organisms in the field, avoid the sensitive period of natural enemies to pesticides, and choose to apply drugs to the period when the natural enemies have no influence or influence and the lethality of the pests is high.
Fourth, the use of appropriate dosage: in the amount of dosage, it is necessary to change the habit of pursuing a high dose of 99% or more in the past . Choose the right dose. The first is the appropriate concentration of the drug solution or powder, and the other is the appropriate amount of use per unit area . In general, the higher the concentration, the greater the effect, but more than effective concentration, not only wasteful, but also may cause injury; less than effective concentration, but also to achieve the purpose, the use of trace amounts of toxic substances even less than prevention also Pests have a stimulating effect. If the dosage per unit area is too much or insufficient, the same adverse consequences as described above will occur. Therefore, the concentration and dosage must be determined according to the regulations before application.
V. Rotational medication: A long-term repeated use of a pesticide against a pest, killing individuals with sensitive genes, and preserving individuals with resistance genes. From generation to generation, individuals with significant resistance are gradually formed. population, at a very low level of such susceptibility of pesticides, control effect significantly. There is also the phenomenon of "interactive resistance", that is, a pest is resistant to a certain agent, and is also resistant to certain agents that have been used . And delaying one of the effective ways to overcome drug resistance, they are alternately administered rotation pesticides. In general, it is possible to delay the occurrence of drug resistance by alternately applying two or more kinds of agents having different action mechanisms . But pay attention to this interaction pest resistance problems, to choose the potency of anti-drug interaction is not used interchangeably, otherwise reach the purpose of preventing the occurrence of drug resistance. There is some kind of drug-resistant strains of pests, but for another agent to increase the sensitivity, a phenomenon known as "negative interaction drug resistance", if the rotation of medication, use of negative cross-resistance Pesticides are more effective in replacing pesticides that have become resistant to harmful organisms.
6. Rational mixing of pesticides: Scientific and rational mixing of pesticides is conducive to giving full play to the role of existing pesticide formulations. There are two methods mix now, one of the two or more pesticide mixed processing, made of complex formulations, carried out by the pesticide industry commodity production, the market, prevention and treatment do not need to re-formulated. The second is the use of on-site mixing. Control personnel are very likely to be harmful to the actual needs of the prevention and control of the upper body, and two or more kinds of pesticides are mixed and applied.
The types of mixed pesticides are insecticide plus synergist, insecticide plus insecticide, fungicide plus fungicide, herbicide plus herbicide, insecticide plus fungicide, insecticide plus herbicide, fungicide Add herbicides, etc. Mixed use can overcome the resistance of pests to pesticides; can expand the types of control objects to achieve a multi-drug treatment; can extend the life of pesticides of old varieties; can play a synergistic effect; can also reduce the cost of prevention.
However, when mixing, you can't arbitrarily combine and have a serious scientific attitude. The current distribution of the field should adhere to the principle of mixing and testing first. Generally, the following points should be considered, that is, the synergistic effect should be produced after the mixing of two or more pesticides , rather than the reduction effect; the toxicity to humans and animals should not be increased, or the multiplication ratio should be small; the phytotoxicity to crops should not be increased. , safer; acid-base reaction should not occur, i.e., the case of acid decomposition or alkali decomposition case; flocculation and should not generate large amount of precipitate.
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