How to Choose Pesticides for Greenhouse Vegetables

For many years, the prevention of pests and diseases advocated the principle of harmless control based on "agricultural control, physical control, biological control, and chemical control." However, in order to ensure stable production and high yield of vegetables in greenhouses, it is inevitable to use a variety of pesticides. Therefore, the problems that should be paid attention to in selecting pesticides and spraying pesticides are the key to understanding and mastering. Here is China Agricultural Net to introduce it.

First, scientific and rational drug use, delay drug resistance.

1, to avoid long-term single-use drugs, select new varieties of pesticides

Single medications can easily produce resistance to pests and diseases. Reduce control efficiency. New varieties (usually used in this greenhouse) can reduce the number of medications, reduce production costs, improve control effectiveness, and slow the development of drug resistance.

2, master the appropriate dosage and drug concentration

Under normal circumstances, the higher the concentration of the drug, the better the drug efficacy, and what is the slow and controlled release of pesticides. However, an excessively high concentration of the drug causes residues of the drug to easily produce phytotoxicity, and it also increases the resistance of the bacteria. To strictly follow the instructions for the preparation of liquid multiples.

3, control the frequency of application, master a reasonable interval

The number of application times is too much, the interval is too short, and it is prone to phytotoxicity. General chemicals are valid for 7-10 days, so each interval should be 7-10 days. The monthly frequency of application of greenhouse vegetables is 2-3 times and no more than 4 times.

Second, seize the critical period of disease prevention and prevent it as soon as possible.

The first critical period is the seedling period. During the nursery period, the seedlings are small and the disease resistance is weak and vulnerable to infection by pathogens. A protective fungicide such as chlorothalonil and mancozeb should be sprayed to ensure that the seedlings are not infected by pathogens.

2. The second critical period is after the establishment of the phytophage. After the seedlings are slowly growing, the growth rate of the seedlings is quickened, and the disease is easy to occur. A protective spraying should be carried out to form a protective film around the plants to prevent germs from spreading.

3, the third key period in the young fruit period. After flowering, the results turned from vegetative growth to reproductive growth and vegetative growth. The leaves were poorly nutritious and susceptible to disease. Control should be sprayed in time.

4. The fourth critical period is at the peak of harvest. During the harvesting period, most of the nutrients absorbed by the plants were taken away by the fruits. The disease resistance of the plants was significantly weakened. At the same time, the frequency of watering increased, the humidity in the greenhouse was high, and the disease was easy to develop. Therefore, before the watering, we must first spray and prevent it. At the same time, we must carry out field inspections and find that the central diseased plant is used immediately.

Third, improve the spraying technology to ensure the quality of medication.

1, spraying should be comprehensive. Spraying should be done without leakage, no heavy spraying, no leakage, no leakage. Spray from the bottom of the plant to the top and spray it evenly.

2, to focus on when spraying. The susceptibility diseases around the central diseased strains should be sprayed, and the upper leaves of the plants must be sprayed with susceptibility to disease.

3, determine the spraying time. Under normal circumstances, strong light, high temperature, high temperature, crop transpiration, respiration, photosynthesis strong, stomatal surface stomata open, is conducive to the entry of agents, in addition to humidity and large leaf surface liquid drying speed is slow, easy pharmaceutical Absorb and enhance efficacy. However, when the light is too strong and the temperature is too high, it may cause photolysis or phytotoxicity of the drug. Therefore, it should not be sprayed before and after noon. In practice, the best application time is best when the sunny morning temperature is 20-25°C and the humidity is 70-75%.

Fourth, master scientific prevention, pay attention to four principles of medication

One is the timely medication. The pesticide should be applied at the initial stage of the occurrence of pests and diseases. In particular, the environment should be warm and moist in the greenhouse. It is not appropriate to spray on cloudy or rainy days to prevent the temperature in the greenhouse from being too high and to reduce the efficacy. At the same time, do not use sulfur preparations to prevent diseases of melons and vegetables at high temperatures to avoid phytotoxicity.

The second is rotation of medication. Pesticides of different types and mechanisms of action should be used interchangeably. For example, dimethoate belongs to organophosphorus pesticides, and the enemy kills pyrethroid pesticides. Their mechanisms of action are different. If attention is paid to rotation, the pest resistance can be avoided or delayed. produce.

The third is safe medication. In the production of vegetables, high-efficiency, low-toxicity, low-residue pesticides should be used. Never increase the concentration of the drug at random. The number of drugs used should not be excessive, and the drug should be used strictly according to the safety period. At the same time, the use of highly toxic pesticides such as organic chlorine, carbofuran, and methamidophos must be strictly prohibited.

Fourth, do not purchase expired pesticides. When purchasing or using chemical pesticides, the quality of pesticides must be identified. If you purchase or use pesticides that have already failed, it will not only directly cause economic losses, but also cause phytotoxicity.

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