Small mesh orchard, vegetable cover to prevent pests The choice of insect net: As a new type of agricultural covering material, insect-proof net is usually available in 25, 30, 40, 50, 60 mesh and other commonly used specifications, and the color is divided into white, silver-gray, etc. The specifications of the insect net should be determined according to the purpose of use, such as insect prevention or frost prevention, fruit drop prevention and rainstorm prevention. Generally choose 40 mesh white insect net. When used for the breeding of non-toxic seedlings, 60 meshes can be selected to ensure the isolation and control of virus and germ-transmitting vector insects such as psyllids and aphids. The main function of covering the insect net: 1. Block foreign organisms According to the size of its aperture, insect nets that block foreign organisms can play an important role in blocking pests, birds and rodents that harm crops. In recent years, due to changes in planting and cultivation systems, renewal of varieties and changes in climate, the types, distribution and damage of citrus pests have also undergone corresponding changes. There are also pest mites, scale insects, whiteflies, aphids and leaf miners. In recent years, the damage caused by canker in southern production areas has shown a slow upward trend. Insect-proof net covering technology is one of the important measures to implement virus-free seedlings of citrus and other fruit trees. It is mainly used to prevent the occurrence and spread of poisonous pests such as citrus aphids and citrus psyllids, and to ensure the safe production of virus-free seedlings of fruit trees. Experiments show that under the condition of 40 mesh insect control nets, the number of psyllids, red spiders and leaf miners in the net house is significantly less than that in the outdoor, indicating that the insect control net can be used as an effective means of reducing pests. Number of citrus pests. The disease prevention effect of the insect net is mainly manifested in the isolation of virus transmission routes, drug production routes and poisonous insect invasion routes, thereby effectively inhibiting and reducing the emergence and harm of adult insects. To a certain extent, it can inhibit the occurrence of some bacterial and fungal diseases (such as anthracnose). Canker is the second most common infectious disease in citrus cultivation after Huanglongbing. The main routes of infection are wind, rain, humans, and insects. As a relatively independent space, the insect control net not only effectively reduces the frequency of artificial transmission, but also greatly reduces the spread of canker because of the isolation of the main transmission route of the invasion of adult pests that transmit viruses. The comparison test between net and open field shows that the incidence of canker disease differs by more than 80% between citrus grown with insect net and the open field control area without insect net. 2. Improve the temperature and lighting in the network Covering the insect net can reduce the light intensity, adjust the soil temperature and air temperature and humidity, and at the same time can reduce the precipitation in the net room, reduce the evaporation of water in the net room, and reduce the transpiration of citrus leaves. Citrus Rutaceae. Likes warm and humid climate, strong cold resistance. Tropical and subtropical evergreen fruit trees. Its growth, development, flowering and fruiting are closely related to environmental conditions such as temperature, sunshine, moisture, soil, wind, altitude, and terrain. related. Citrus is a semi-negative plant with a wide range of adaptations to sunlight. The light intensity is 10000-40000 lx, and the annual sunshine hours are about 1000-2700 hours, which can meet the growth needs of citrus. 3. Prevention and treatment of Huanglongbing At present, Huanglongbing has become a serious disease affecting the development and layout of the global citrus industry. In South China, before new breakthroughs were made in the prevention and control technology of Huanglongbing, the control of psyllids had become an important factor in controlling the spread of Huanglongbing, affected by factors such as regional economic and social development, orchard management, structure and structure. The quality of rural labor force. Psyllid is the only natural transmission vector of Huanglongbing, so the control of psyllid is particularly important. The citrus psyllid has a high disease transmission rate (the disease transmission rate of a single psyllid is 70% to 80%), has strong migration and rapid reproduction capabilities, and is resistant to a variety of pesticides. one of the effective means. 4. Prevent fruit drop In summer in South China, meteorological disasters such as heavy rain and typhoons occur frequently. If covered with insect nets, it can reduce the fruit drop caused by heavy rain, especially during the physiological fruit drop period. The effect of preventing fruit drop is more obvious. The experimental results of Fan Shulei et al. show that the treatment of covering insect nets can significantly increase the rate of commercial fruit and significantly reduce the rate of fruit drop. 5, staggered peak market, citrus preservation In the insect control net, the spring will warm up early, the phenotype of navel oranges will be 5 to 7 days earlier, and the fresh fruit will be 7 to 10 days earlier, and the peak season will be staggered, which can increase the income of fruit farmers and create higher value. Covering with a layer of film can increase the temperature in the shed by 2 to 3 °C, prolong the supply period of fresh fruits, realize the staggered peak market, and avoid unnecessary losses caused by the peak period. 6. Shelter from the wind and rain The insect-proof net has small mesh, high mechanical strength, and good weathering effect. In production, the frame material and fruit trees are often washed away due to excessive wind. Covering 25 mesh insect nets can reduce the wind speed by 15%~20%, and using 30 meshes can reduce the wind speed by 20%~25%. Hail and heavy rain in summer can cause mechanical damage to fruit trees. Covering the insect net can prevent hail from impacting fruit trees and reduce the impact strength of rainstorms.