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The role of insect net:
Citrus is the largest evergreen fruit tree in the world. Studies have shown that the use of insect-proof nets can greatly reduce the use of pesticides, which is beneficial to the development of ecological agriculture and is one of the key technologies in the production system of pollution-free agricultural products. Insect-proof net covering can be used to prevent frost, rainstorm, fruit falling, insects and birds, etc. At the same time, it can ensure the yield and quality of fruit and increase economic benefits. As a result, insect-proof net coverage may become a new model of fruit tree facility cultivation.
 The main function of covering insect nets
1. Block foreign organisms
According to the size of its aperture, the insect-proof net to block foreign organisms can play a significant role in blocking pests, birds and rodents that harm crops. In recent years, due to the change of planting and cultivation system, the renewal of varieties and the change of climate, the types, distribution and damage of citrus pests have also changed accordingly. Still pest mites, scale insects, whiteflies, aphids and leaf miners. In recent years, the damage caused by canker in southern production areas has been slowly increasing.
Insect-proof net covering technology is one of the important measures to implement virus-free seedling breeding of citrus and other fruit trees. It is mainly used to control the occurrence and spread of virus-borne insects such as citrus aphids and citrus psyllids, so as to ensure the safe production of virus-free seedlings of fruit trees. Experiments have shown that the number of psyllids, red spiders and leaf miners in the net room is significantly smaller than that in the outdoor under the condition of 40 mesh insect control net, indicating that the insect net can be used as an effective means to reduce the number of citrus pests.
The disease prevention effect of the insect control net is mainly manifested in the isolation of the ways of virus transmission, drug production and the invasion of poisonous insects, so as to effectively inhibit and reduce the appearance and harm of adult pests. To a certain extent, it can inhibit the occurrence of some bacterial and fungal diseases (such as anthracnose). Canker is an infectious disease that is second only to Huanglongbing in citrus planting. Its infection routes are mainly divided into wind, rain, human and insect transmission. As a relatively independent space, insect nets not only effectively reduce artificial The frequency of transmission, and because the main transmission route of the invasion of the adult insects of the virus-transmitting pests is isolated, the transmission of canker pathogens is greatly reduced. The comparison test between the net and the open field showed that the incidence of canker disease differed by more than 80% between the citrus planted in the insect control net and the open field control area without the insect control net.
2. Improve the temperature and light in the network
Covering the insect-proof net can reduce the light intensity, adjust the soil temperature and air temperature and humidity, and at the same time, it can reduce the precipitation in the net room, reduce the water evaporation in the net room, and reduce the transpiration of citrus leaves. Citrus is a plant belonging to the Rutaceae family. It prefers warm and humid climates and has strong cold resistance. It is a tropical and subtropical evergreen fruit tree. Its growth and 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 and has a wide range of adaptation to sunlight. The light intensity is 10,000-40,000 lx, and the annual sunshine hours are about 1,000-2,700 hours, which can meet the growth needs of citrus.

Scattered light is beneficial to enhance photosynthesis, but too strong direct light is often not conducive to the growth of citrus, and it is easy to cause burning of fruits and branches and leaves. After covering the insect-proof net, the indoor air temperature of the net under each weather type was higher than that of the control during the recorded period. Although the highest and lowest temperatures in the net room were higher than those of the control, the increase was not obvious, indicating that the effect of covering insect nets was small. At the same time, in terms of humidity, after covering the insect-proof net, the relative humidity of the indoor air in the net is higher than that of the control, among which the humidity is the highest in rainy days, but the difference is the smallest and the increase is the lowest. After the relative humidity in the net room is increased, the transpiration of citrus leaves can be reduced. Water affects fruit quality development through precipitation and relative air humidity. When ecological factors are favorable for fruit growth and development, fruit quality is good.
3. Prevention 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 due to the regional economic and social development, orchard management mode, and the structure and quality of the rural labor force. Psyllids are the only natural transmission vector of Huanglongbing, so the prevention and control of psyllids is particularly important. Citrus psyllid has high disease transmission (the disease transmission rate of a single psyllid is 70% to 80%), migratory and rapid reproduction ability, and has developed resistance to a variety of pesticides… The use of insect-proof net cultivation technology, It is one of the effective means to prevent and control Huanglongbing.
4. Fruit drop prevention
In the summer of South China, there are many meteorological disasters such as rainstorms and typhoons. If the insect-proof net is used to cover, it can reduce the fruit drop caused by the rainstorm, especially in the physiological fruit drop period. The effect of preventing fruit drop is more obvious. The experimental results of Fan Shulei and others showed that the treatment of covering insect nets can significantly increase the commercial fruit rate and significantly reduce the fruit drop rate.
5, staggered peak market, citrus preservation
In the insect control net, the spring picks up early, the navel orange phenotype is 5 to 7 days earlier, and the fresh fruit is 7 to 10 days earlier, and the peak season is staggered, which can increase the income of fruit farmers and create higher value. Covering the net with another layer of film can increase the temperature in the shed by 2 to 3 °C, prolong the supply period of fresh fruits, realize staggered market listing, and avoid unnecessary losses due to peak periods.
6, shelter, windproof
The insect-proof net has small mesh and high mechanical strength, so it has a good effect of preventing wind and rainstorm erosion. In production, due to excessive wind, the frame material and fruit trees are often washed away. Covering with 25 mesh insect net can reduce the wind speed by 15% to 20%, and using 30 mesh can reduce the wind speed by 20% to 25%. Hail and rainstorm in summer cause mechanical damage to fruit trees. Covering with insect-proof net can prevent hail from impacting fruit trees and reduce the impact strength of rainstorm. After the rainstorm, the weather is suddenly sunny again, the temperature rises, and the moisture of the plants is seriously imbalanced, which often causes rotten roots. The insect-proof net coverage can avoid the rapid changes in the temperature of the microclimate in the shed and alleviate the indirect harm of the rainstorm and sunny weather.