Reasonable use of pesticides should pay attention to matters

The use of pesticides has always been the main method for pest control. However, there are many unreasonable places in the process of using pesticides, which affects the efficacy of pesticides. This paper discusses the problems existing in the daily use of pesticides, from the nature of pesticides, Using methods, reasonable mixing and cross-use, summarized how to improve efficacy.

Chemical control pests and diseases have been widely used in agricultural production due to their high efficiency, quick effect, and special effects. At present, there are still many unreasonable places in the process of using pesticides, resulting in the waste of pesticides, environmental pollution, and the emergence of pest resistance. In order to ensure the quality and safety of agricultural products and protect the ecological environment, the state expressly prohibits the use of highly toxic and high-residue pesticides. Therefore, how to achieve economical, safe and effective use of pesticides should pay attention to the following aspects:

1 to achieve symptomatic medication

All kinds of pathogens, pests and weeds have different body structures, physiology, and habits. The sensitivity or resistance to drugs is very different. The same agent has different efficacy for different control objects; the same type of control object is different. The agents also show different resistance. Therefore, according to different control objects and crops, select the appropriate pesticide species. When selecting pesticides, we must make clear the physiological mechanism and hazard characteristics of the control objects, as well as the variety characteristics and growth period of fruits, vegetables, crops, so that "the right medicine."

At present, the phenomenon of indiscriminate use and abuse of pesticides in rural areas is prominent. The main manifestations are: do not understand the pesticide control objects, do not understand what pests and diseases occurred, but instead use drugs indiscriminately, and often find methamidophos to control various pests in the fields. Use carbendazim to prevent various diseases. Therefore, it is necessary to understand the pesticides used, such as the net effect of fleas on the control of fleas, but the control effect on the leaf miners is poor; deltamethrin to lepidopteran (moth) larvae, orthoptera pests, etc. There are special effects, but the control effect on apple leafhoppers is poor; rotenone is highly toxic to aphids and ticks, but it is ineffective against the larvae of the noctuid family (Tiger magpies, Ctenopharyngocephalus); diflubenzuron to Lepidoptera Diptera larvae are highly toxic but have little toxicity to Coleoptera and predatory spiders. Therefore, before the application of pesticides, it must be based on the object to be controlled, choose its sensitive pesticide use.

In addition, we must consider the growth characteristics of the damaged plants to select pesticides to avoid phytotoxicity. Dimethoate on the stone fruit trees, trichlorfon susceptible to phytotoxicity Pak Pear, peaches in the growing season should not use Bordeaux mixture, gold crown, red jade and other apple varieties are also very sensitive to it. Melons and beans are crops that are sensitive to pesticides. Dichlorvos, aluminum phosphonium, dichlorfon, dimehypochlor, and vancomycin should be used with caution in cucurbit crops; dichlorvos and trichlorfon should be used with caution in leguminous crops. , Insecticide double, Weibing Wei et al. For the melon and legume crops, it is easy to produce phytotoxicity with the above pesticide species, and it is best to use other pesticide species instead. The scope of application of biological pesticides is relatively narrow, with strict selectivity. For example, kasugamycin only controls rice blast, and Lubao 1 only controls dodder.

2 Note the use period

We must do a good job of investigating diseases, pests and weeds, and master the best period of prevention and treatment. Proper drug use is the key to improving the effectiveness of pesticide application. In order to ensure the control effect and avoid the abuse of pesticides, the method of “two inspections and two determinations” should be adopted, that is, insect pests should be checked, and the population density should be checked, and the target of prevention and control should be determined. The progress of pest development should be determined and the control period should be determined. For disease, it is usually to check the incidence, determine the object of prevention and control; check the degree of disease, determine the appropriate period of control. According to the law of occurrence of pests and living habits, timely medication, can significantly improve the efficacy, reduce the number of spraying and reduce the concentration of use.

Chemical prevention requires prevention as the main treatment and early treatment. Insecticides were used between the egg hatching stage and the larvae's 2nd instar stage. The fungicide was sprayed when the diseased leaf rate was 5% at the initial stage of disease. Kak died to prevent apple all-jaw clams, preferably before or after flowering, spraying 5% stuck 1000 ~ 1500 times solution, effective control period of up to 2 months. All kinds of diseases should be applied when the spores do not re-infect. For example, in the critical period of prevention and control of grape black spot disease, apple rot disease should scrape the diseased part in the early spring to prevent spores from spreading. General nymph stage and low resistance before 3rd instar larvae are the best prevention and control period for various pests. For example, Peach leaf miner should be in the peak period of wintering or adult egg laying, ie spraying insecticides after flushing. Agent control effect is good.

3 Pay attention to spray concentration and times

Spray pesticides to achieve the appropriate concentration of preparation, the number of spraying scientific intervals. Reasonable use concentration and spraying times can not only meet the prevention and control requirements but also save expenses. Each pesticide is marked in the instructions for use concentration, generally refers to the optimum concentration, when it is more likely to occur phytotoxicity or produce other adverse results (enhanced pest resistance, serious pollution, etc.), it is best not to spray More than this use concentration. It is not advisable to blindly increase the concentration to increase the effect of prevention and control, because the sensitivity to the concentration of plants and pests at different developmental stages is also different, and plant seedlings, anthesis and tender parts are prone to produce phytotoxicity, so that the drug concentration Easy to lower, the control of larvae requires less concentration than the control of adults.

The number of sprayings depends on the degree of occurrence of the pests and the effective period of application of the pesticides. When the pests reach the field control index, they should be sprayed in time. For example, if pests of peach fruitworms are controlled in the field, when the rate of eggs in the field reaches 1%, they should be controlled. When each leaf has 2 to 3 heads of Hawthorn red spider, it should be sprayed and prevented. After the expiration date, the insects should still spray on the control indexes. 2 times, if it is not within the prevention and control index, it can be suspended, and then the number of insect populations will rise again after the prevention. For all kinds of diseases, prevention should be taken to ensure that the protective agent is sprayed once every half month, such as Bordeaux mixture or carbendazim. The fungicide should be sprayed in the early stage of disease, and many diseases and insect pests are prone to occur in rainy days. Several times, sunny days can be sprayed a few times, can not cause excessive residue.

4 Rationally mix pesticides

According to the physicochemical properties of pesticides, the use of several pesticides can be rationally mixed, which can not only expand the scope of prevention and control, improve the control effect, but also delay the occurrence of pest resistance. When mixing, the concentration of various pesticides when used alone can be appropriately reduced, and the desired effect can also be achieved.

When pesticides are mixed, their preparation should pay attention to the following issues: 1 There must not be toxic drugs in the mixed pharmaceuticals. 2 If there is a wettable powder that is used as a mixed agent, firstly combine the wettable powder with the rest. Such as: Wet trichlorfon powder and organic phosphorus EC mixed, first diuretic powder diluted, and then use this solution to prepare organic phosphorus. 3 first with Bordeaux fluid, followed by other agents. 4 When using two kinds of wettable powders, it is necessary to first mix the wettable powder and add water to dilute it. 5 Pesticides that encounter decomposition or failure of basic substances cannot be mixed with basic drugs. Dimethoate, dichlorvos and other organophosphorus insecticides are neutral or slightly acidic pesticides. They will quickly decompose and fail in alkaline solutions. Therefore, these pesticides cannot be treated with alkaline pesticides and other alkaline substances such as ammonia, Mix lime, soap, and alkali, otherwise it will reduce efficacy and cause phytotoxicity. 6 Although trichlorfon is an acidic pesticide, due to its special chemical properties, it can be quickly converted into a very strong contact dichlorvos with a certain amount of soap or alkali. At the same time, the efficacy period is shortened. In the fungicide, for example, zeocin and metsammonium may also be decomposed due to strong alkaline pesticides, and therefore cannot be mixed with lime sulfur or Bordeaux mixture. 8 Chemical reactions occur after mixing, and pesticides and fertilizers that can cause phytotoxicity cannot be mixed. For example, the mixture of lime sulfur and Bordeaux mixture generates lead polysulfide, destroys Bordeaux mixture and lime sulfur, increases the amount of dissolved copper, and causes serious damage. After spraying Bordeaux mixture, it takes about 30 days to spray again. Lime sulfur. 9 When various wettable powders are mixed with other chemicals and fertilizers, if there is a large amount of flocculation phenomenon, the efficacy will be reduced, and the crops will be phytotoxic.

5 Alternate use at a proper time

In the production, some new pesticides are used continuously, and after the control effect is reduced, they blindly increase the concentration and increase the number of applications. As a result, the new pesticides are quickly eliminated without the initial control effect; An agent with a similar pharmaceutical agent or mechanism of action can lead to an increase in the resistance of pests and pathogens to the agent, resulting in a decrease in the control effect and adversely affecting the prevention and treatment work. Therefore, in order to avoid the formation of drug resistance, pesticides of different species and different mechanisms of action should be used interchangeably. For example, organophosphorus pesticides, pyrethroids, carbamates, organic nitrogen, biological agents, and plant pesticides in insecticides have different mechanisms of action. Among fungicides, antibiotics and benzimidazoles are used interchangeably with sulphur preparations, copper preparations and dexamethasone. The control effect is very good. Alternating use of organophosphorus and pyrethroids, alternating use of contact inhibitors and systemic adsorbents is more effective than single application of a pesticide. It should be noted that the interval between use of Bordeaux mixture and tetromycin should be more than 20 days, otherwise it is prone to phytotoxicity.

In short, chemical control should use highly efficient, low-toxic, low-residue, selective pharmaceutical agents. In combination with the popularization and application of new insecticidal lamps, we must actively promote integrated control technologies so that chemical control, physical control, and biological control can be combined. , Minimize the impact of pesticides on natural enemies of pests and surrounding organisms, reduce environmental pollution and prevent the occurrence of public hazards, so as to reduce the negative impact of chemical pesticides on the environment. This is a guarantee for improving the quality of agricultural products and developing green agriculture.

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