Environmental protection is an issue that has received much attention in agricultural production in recent years. Under the general trend of emphasizing the transformation of agricultural production mode, physical control of plant diseases and insect pests is becoming more and more popular. Many farmers who are engaged in greenhouse planting choose to install insect nets, which are economical and practical and meet the requirements of ecological agriculture, thus reducing the damage of pesticides to soil and crops. Today, I'd like to introduce some knowledge about insect nets.
Why are insect nets installed?
1. Can effectively prevent insects. After covering the insect net, the insect pests such as cabbage caterpillar, diamondback moth and aphid can be basically eliminated. After agricultural products are covered with insect-proof nets, various pests such as cabbage caterpillar, diamondback moth, cabbage caterpillar, prodenia litura, yellow koji beetle, ape leaf worm, aphid and the like can be effectively prevented from damaging. According to experiments, the control effect of the insect net on cabbage caterpillar, diamondback moth, cowpea pod borer and Liriomyza sativae is 94-97%, and the control effect on aphids is 90%.
2. It can prevent diseases. Virus transmission will bring disastrous consequences to greenhouse cultivation, especially aphid transmission. However, the installation of insect-proof nets in greenhouse cuts off the transmission route of pests and greatly reduces the incidence rate of virus diseases, with a control effect of about 80%.
3. Adjust the temperature, soil temperature and humidity. In the hot season, the greenhouse is covered with white insect-proof net. The test shows that in the hot July to August, in the 25 mesh white insect-proof net, the temperature in the morning and evening is the same as that in the open ground, while in the sunny day, the temperature at noon is about 1℃ lower than that in the open ground. From March to April in early spring, the temperature in the insect net covered shed is 1-2℃ higher than that in the open field, and the ground temperature of 5 cm is 0.5-1℃ higher than that in the open field, which can effectively prevent frost. In addition, the insect net can prevent some rainwater from falling into the shed, reduce the field humidity, reduce the incidence of diseases, and reduce the evaporation of water in the shed in sunny days.
4. It has shading effect. Summer light intensity is large, strong light can inhibit the vegetative growth of vegetables, especially leafy vegetables, and insect nets can play a certain shading role, the shading rate of 20-22 mesh silver-gray insect nets is generally 20-25%.
The insect-proof net is similar to a window screen and has the properties of high tensile strength, ultraviolet resistance, heat resistance, water resistance, corrosion resistance, aging resistance and the like, is nontoxic and tasteless, and has a service life of 4-6 years in general and up to 10 years in maximum. It not only has the advantages of sunshade net, but also overcomes the disadvantages of sunshade net, so it is worth promoting vigorously. Then the question arises: What kind of insect net should we choose?
In autumn, many pests begin to transfer to the shed, especially some moth and butterfly pests. Due to their large size, vegetable farmers can use insect nets with relatively small mesh numbers, such as 30-60 mesh insect nets. However, for those with more weeds and whiteflies outside the shed, it is recommended that vegetable farmers use a denser insect-proof net, such as 40-60 mesh, according to the smaller size of whiteflies to prevent them from entering through the holes of the insect-proof net.
For example, thrips have a strong affinity for blue, and the use of blue insect nets can easily attract thrips outside the shed to the surroundings of the shed. Once the insect nets are not covered properly, a large number of thrips will enter the shed to cause harm. The use of white insect nets will not cause this phenomenon in the greenhouse, but when used in conjunction with the sun screen, it is appropriate to choose white. Also, a silver grey insect-proof net has a better repelling effect on aphids, the black insect-proof net has a remarkable shading effect, and is not suitable for use in winter and even cloudy days.
In general, compared with the spring and autumn season and summer, the temperature is lower and the light is weaker, so white insect net should be selected. In summer, black or silver grey insect net should be selected for shading and cooling. In areas where aphids and viral diseases are serious, silver gray insect nets should be selected in order to avoid aphids and prevent viral diseases.
Matters needing attention
1. Before sowing or planting, use high temperature to close the shed or spray low toxicity pesticide to kill parasite pupae and larvae in the soil.
2. When planting seedlings, it is best to bring medicine into the shed and select robust plants free from diseases and insect pests.
3. Strengthen the daily management, in and out of the greenhouse to close the door, before the agricultural operations to disinfect the relevant objects, to prevent the introduction of viruses, in order to ensure the use of insect net effect.
4. Always check whether there is any tear in the insect-proof net. Once found, it should be repaired in time to ensure that there is no pest invasion in the greenhouse.
5. Ensure coverage quality. The insect-proof net shall be completely covered, and all sides shall be tightly pressed with earth, and fixed firmly with film pressing lines. Doors entering and leaving large and medium sheds and greenhouses must be fitted with insect-proof nets, and attention should be paid to closing them immediately when entering and leaving. The small arched shed is covered with insect-proof net, and the height of the shed is obviously higher than that of crops, so as to prevent vegetable leaves from clinging to the insect-proof net and prevent pests from eating or laying eggs on the vegetable leaves from outside the net. There should be no gap between the insect-proof net used for closing the air outlet and the transparent cover, so as not to leave a passage for pests.
6. Comprehensive supporting measures. In addition to insect net coverage, combined with comprehensive supporting measures such as disease and pest resistant improved varieties, heat resistant improved varieties, pollution-free package fertilizers, biological pesticides, pollution-free water sources, micro-spray micro-irrigation, etc., better results can be obtained.
7. Proper use and safekeeping. After the insect net is used in the field, it should be collected in time, washed, dried and rolled to prolong its service life and increase its economic benefits.
Physical control and biological control have the advantages of not polluting the environment, being safe for crops, people and animals, and being safe for food. As one of physical control, insect prevention net is the demand for future agricultural development. It is hoped that more farmers can master this method and achieve better economic and environmental benefits.