一 、 Pest control principle of insect net
The insect-proof net uses artificially constructed barriers to keep pests out of the net, thereby achieving the purpose of preventing insects, preventing diseases and preserving vegetables. In addition, the light reflected and refracted by the insect net has a certain repellent effect on the pests.
Second, the role of insect nets
1. Insect-resistant insects After covering the insect-proof net, vegetables can basically be exempted from various pests such as Pieris rapae, Plutella xylostella, cabbage night moth, Spodoptera litura, yellow-leaf beetle, leaf ape, and aphid. According to the test, the insect net has 96% control effect on cabbage cabbage worms, diamondback moth control effect is 94%, pea pupae control effect is 97%, leaf spot fly control effect is 95%, and aphid control effect is More than 90.
2. Disease prevention Prion disease is a catastrophic disease on a variety of vegetables, mainly caused by insects, especially aphids. The pest control net cuts off the main pupal-borne virus, which greatly reduces the infection of vegetable viruses. According to tests, after covering insect nets, the control effect of spring tomato virus disease reached 88.5%, with an increase in yield of 24%, and the control effect of Fucao virus was 79%, with an increase of 22%.
3. Adjusting the air temperature and soil temperature The test shows that in hot July to August, the temperature of morning and evening in the 25-mesh white insect net is the same as that of the open field, and the sunny day is about 1 ° C lower than the open field at noon. In early spring from March to April, the temperature in the insect-proof net covering shed is 1 ~ 2 ℃ higher than the open field, and the 5cm ground temperature is 0.5 ~ 1 ℃ higher than the open field, which can effectively prevent frost.
遮光 4. Shading and temperature control The shading rate of the 25-mesh white insect net is 15-20%. The relative humidity of the air in the net is about 5% higher than that of the open field and about 10% higher after watering. It has a certain moisturizing effect.
5. Rainstorm resistance, strong wind resistance Rainstorm hits insect nets, the rainfall decreases by 21.6%, falling on the net has become drizzle, and the impact is weakened, which is beneficial to the development and growth of vegetables. The wind speed in insect nets can be reduced by 15-20%, which has a better anti-typhoon effect.
3. Cover form of insect net
1. Covering the shed Cover the insect-proof net directly on the shed and compact it with soil or bricks. Leave the front door open for easy access.
2. Covering of small arch sheds: Bamboo slabs or steel bars are bent into arch sheds to be inserted into the field surface, and insect-proof nets are covered on the arch frames, and then watered directly on the nets until the harvesting.
3. Horizontal scaffolding cover A field of 2000-3500 square meters is covered with insect nets. This form saves net yarn and net rack and is easy to operate.
Fourth, the application of insect nets on vegetables
1. Protected vegetable production 地 It is mainly used in summer and autumn pakchoi, cabbage, cauliflower, solanaceous fruits, and melon vegetables.
2. Summer and autumn vegetable nursery season is the autumn and winter vegetable nursery season. There are often unfavorable factors such as high temperature, heavy rain and strong light. Frequent diseases and insects are difficult to raise seedlings. Applying insect nets can increase the emergence rate, seedling rate and seedlings. Quality. For example, the breeding of aphids against insect nets can effectively control the virus disease of eggplant fruits and melons in autumn, and cultivate strong seedlings without diseases, which has an obvious effect of increasing yield. Insect screens are suitable for use with shade nets for better results.
Fifth, the use of insect nets
1. According to the characteristics of vegetables, select appropriate insect-proof nets. For vegetable production, it is appropriate to choose white or silver-grey nets with a mesh size of 20 to 32. Black insect-resistant nets should be used for shade-resistant vegetables that require enhanced shading effects; white insect-proof nets with small meshes and large meshes should be used for hi-light vegetables; silver-gray nets for virus-affected vegetables are most effective in preventing aphids. On the premise of being able to effectively prevent aphids, the smallest major pests on vegetables, the mesh size should be as small as possible to facilitate ventilation.
2. Soil disinfection and chemical weed control before covering to kill the eggs and germs remaining in the soil and control the growth of weeds.
1 (1) The soil is plowed, sun-dried, and disinfected before covering. The methods such as spraying, watering, and poisonous soil are used to kill the eggs and cut off the transmission path. It can be sprayed with 3-4 kilograms of diene powder per 667 square meters or trichlorfon and phoxim for soil treatment, and Miller granules can be used for soil treatment of 2-5 kilograms per 667 square meters to kill underground pests. Tigers, badgers, etc.
(2) In order to protect the tightness of insect nets, it is not advisable to enter the nets for artificial weeding and thinning. Therefore, before covering insect nets, apply herbicides to fields with a lot of weeds to control herbicides and provide a favorable growth environment for crop production. Spray 80% to 100ml of 72% Duer herbicide every 667 square meters after sowing.
(3) Fine land preparation, sufficient basal fertilizer application, generally no topdressing during growing season. It takes time to apply organically prepared manure in order to avoid the application of raw fertilizers with eggs and germs to the vegetable field.
3. Implement full growth period coverage Insect-proof nets do not have much shading, and there is no need to open the day or night cover or cover the shade. You should implement closed coverage throughout the growth period until the harvest. When the greenhouse is covered, the insect-proof net can be directly covered on the scaffold and compacted with soil or bricks to prevent pests from swimming into the spawning. The net must be pressed firmly with a wire to prevent the net from being blown away by strong winds. When the small arch shed is covered, the height of the shed should be higher than the height of the vegetable crop. Generally, the arch height should be more than 90 cm, to prevent the vegetable leaves from clinging to the insect net, and to prevent pests outside the net from eating vegetable leaves and spawning.
4. Do a good job in comprehensive supporting measures. Under the premise of covering insect nets, take comprehensive measures such as selecting heat-resistant and disease-resistant varieties, applying sufficient rot and pollution-free organic fertilizers, using biological pesticides reasonably, and selecting pollution-free water sources. Rotary crop rotation and soil insecticide treatment before sowing are used to solve the problem.
5. Attention
1 (1) Insect-proof net is made of polyethylene, which is made by drawing and weaving. It has a certain effect of shading and cooling. However, during use, it is tight around, air is not flowing smoothly, and temperature and humidity are relatively high. The study found that the higher the outside air temperature, the greater the increase in temperature and humidity in the network, and the effect of increasing the temperature and humidity of the small shed is more obvious. High temperature and humidity will inevitably be harmful to the growth of vegetables, and will easily cause rotten seeds, rotten seedlings, excessive length, lighter leaf color, and slender plants, and serious emergence of seedlings and withering. Therefore, it is advisable to use greenhouse covering in production, and pay attention to controlling humidity in the greenhouse. According to the experience of Suzhou, from July to August, it can only be covered with a greenhouse. In September, it can be covered with a greenhouse, a small greenhouse or a flat roof.
(2) Due to the strong moisture retention of insect nets, field management is drier than open fields. The watering of pakchoi was changed from water in the morning to night in the morning, and watering in the evening was generally not performed.
(3) After the insect net is covered, the vitamin C and the net vegetable rate are higher than those of the open field, and the appearance and color are better than those of the open field. They are popular in the market, but the chlorophyll content in the leaves is reduced and the nitrate content is increased compared to the open field. Shading is related to having a certain heating effect.
(4) Some vegetable farmers take the net open one week before the harvest of vegetable seedlings, restore the natural environment to grow, make the leaves turn green, and the plants are robust. At the same time, the utilization rate of insect nets can also be improved.
(5) Insect nets have a high investment, and multiple crops should be promoted. Generally, they can be used for half a year from May to October. You can also try to cover in winter and spring to get more returns.
(6) Proper use and storage of insect-proof nets After use in the field, they should be pressed, washed, blown dry, and rolled up in time to extend the service life and increase economic benefits. When they are used again, they should be inspected for damage and plugged leaks Crevice.