Insect-proof net usage technology

1. Choose appropriate insect-proof nets according to the characteristics of vegetables. For vegetable production, it is advisable to use white or silver-gray nets with 20-32 meshes. For shade-tolerant vegetables, black insect-proof nets should be used if the shading effect needs to be enhanced; for light-loving vegetables, white insect-proof nets with fewer meshes and larger meshes should be used; for vegetables that are seriously affected by viral diseases, silver-gray nets are the most effective in avoiding aphids and preventing diseases. On the premise of effectively preventing aphids, the smallest major pest on vegetables, the mesh size should be as small as possible to facilitate ventilation. 2. Disinfect the soil and perform chemical weed control before covering to kill the eggs and pathogens remaining in the soil and control the growth of weeds. (1) Before covering, the soil should be plowed, sun-dried, and disinfected. Spraying, irrigation, and poisoned soil should be used to kill soil pathogens and eggs and cut off the transmission route. You can spray 3-4 kg of benzyl chloride per 667 square meters or trichlorfon and phoxim for soil treatment, or you can use 2-5 kg ​​of Miler granules per 667 square meters for soil treatment to kill underground pests such as cutworms and mole crickets. (2) In order to protect the tightness of the insect-proof net, it is not advisable to enter the net for manual weeding and thinning. Therefore, before covering the insect-proof net, apply herbicides to the fields with more weeds to prevent weeds and provide a favorable growth environment for crop production. After sowing, spray 80-100 ml of 72% Dole herbicide per 667 square meters. (3) Finely prepare the land and apply sufficient base fertilizer. Generally, no topdressing is required during the growing season. When applying organic fertilizer, apply fermented manure to avoid applying raw fertilizer with insect eggs and pathogens into the vegetable field. 3. Implement covering during the entire growth period. The insect-proof net does not provide much light protection, so it does not need to be covered during the day or covered in the sun and covered in the shade. It should be covered in a closed manner throughout the growth period and not be removed until harvest. When covering a greenhouse, the insect-proof net can be directly covered on the shed frame, and the surrounding area can be compacted with soil or bricks to prevent pests from swimming in and laying eggs. The net must be pressed firmly with a netting wire to prevent the net from being blown away by strong winds. When covering a small arch shed, the height of the shed should be higher than the height of the vegetable crops. Generally, the arch height is required to be more than 90 cm to prevent the leaves from sticking to the insect-proof net and prevent pests outside the net from eating the leaves and laying eggs. 4. Take comprehensive supporting measures. On the premise of covering the insect-proof net, take comprehensive measures such as selecting heat-resistant and disease-resistant varieties, applying sufficient decomposed and pollution-free organic fertilizers, using biological pesticides reasonably, and selecting non-polluted water sources. For underground pests, adopt crop rotation and soil pest control before sowing to solve the problem. 5. Matters to be noted (1) The insect-proof net is made of polyethylene and is made of wire drawing and weaving. It has a certain sunshade and cooling effect. However, during use, it is tightly pressed on all sides, air circulation is not smooth, and the temperature and humidity are relatively high. The study found that the higher the outside temperature, the greater the increase in temperature and humidity inside the net, and the heating and humidification effect of the small greenhouse is more obvious than that of the large greenhouse. High temperature and high humidity are bound to be detrimental to the growth of vegetables, and are likely to cause rotten seeds, rotten seedlings, leggy growth, lighter leaf color, and thin plants. In severe cases, seedlings will become stale and die. Therefore, it is advisable to use greenhouse covering in production and pay attention to controlling the humidity inside the greenhouse. According to Suzhou's experience, only greenhouse covering can be used from July to August, and greenhouse covering, small greenhouse covering, and flat covering can be used in September. (2) Due to the strong moisture retention of insect-proof nets, field management should be drier than open fields. Watering of Chinese cabbage is changed from watering once in the morning and evening to watering once in the morning, and generally no watering is done at night. (3) After covering with insect-proof nets, the vitamin C and clean vegetable rate are higher than those in the open field, and the appearance color is better than that in the open field, which is popular in the market, but the chlorophyll content in the leaves is reduced and the nitrate content is increased compared to the open field. This may be related to the shading of insect-proof nets and a certain warming effect. (4) Some vegetable farmers take off the nets one week before harvesting the seedlings to restore the growth in the natural environment, so that the leaves turn green and the plants are strong. At the same time, it can also improve the utilization rate of the insect-proof nets. (5) The investment in insect-proof nets is relatively high, so it is recommended to use them for multiple crops. Generally, they can be used for half a year from May to October. You can also try to cover them on the surface in winter and spring to get more returns. (6) Proper use and storage. After the insect-proof nets are used in the field, they should be pressed, washed, blown dry, and rolled up in time to extend their service life and increase economic benefits. When they are used again, they should be checked for damage and holes and gaps should be plugged in time.