In recent years, with the development of facility agriculture, the vegetable planting structure has been continuously adjusted, providing an environment for the winter survival of pests, prolonging the food chain of pests, causing hazards that have only been harmed in the field in the past to occur in the greenhouse, and annual overlap occurs. The degree of harm is increasing, leading to a decline in the commerciality of vegetables and causing serious economic losses. Recently, thrips in greenhouses in many areas have occurred severely, and the environmental characteristics of greenhouses are prone to the growth and development of thrips, often causing repeated hazards and difficult to control.
First, the symptoms of harm
The hummus mainly sucks the sap of the epidermis of the leaves, buds, flowers or fruits of the host plant by sucking nymphs and adult worms, causing the young leaves to shrink and curl, even yellowing, drying, wilting, and the flowers are white spots or It turns brown, the fruit leaves a scar, and even causes sores, which eventually causes the plants to wither. The pest especially likes to inhabit the flower or on the leaf, and the ovary feeding on the plant pollen or flower causes deformity, developmental hindrance or fruit fading. In addition, Hummer can also spread a variety of viral diseases, causing significant losses.
Second, the law of incidence
Thrips are incomplete metamorphosis, and the whole growth period is divided into four stages: egg, nymph, pupa and adult. Hummers are small insects that have a greenish habit. They occur all year round. In winter, they mainly cause damage and wintering in greenhouses. There are two high-period occurrences in greenhouse vegetables every year. The first one is from November to December in the fall and the second is from March to May. Generally parthenogenesis, occasionally sexual reproduction, spawning in plant tissues, hatching into white thrips after 2 to 3 days, then excessively forming red thrips, then falling into the soil to remove phlegm. Under normal conditions, life history is 15 to 17 days, which is prone to occur under warm and dry conditions.
Third, the reasons why the greenhouse Hummer is difficult to prevent and control
1, dormant night out
Adults are afraid of glare, and they are concentrated in the backlit places. It is active on the surface of the host on cloudy, morning, evening and night. When the conventional contact agent is used, the control effect is not good due to the fact that the spray is not exposed to the insect during the day. In addition, adults are extremely active, and good flying can jump, and can be spread by natural forces. Therefore, once the thrips occur, they spread quickly and are difficult to control.
2, strong reproduction
Hummer's fertility is very strong, and the individual is small and extremely occult, making it difficult to prevent and control. At a stable temperature in the greenhouse, 12 to 15 generations can occur continuously in a year. The eggs are scattered in the mesophyll tissue. Each female lays 22 to 35 eggs normally. In a suitable environment, it takes only 14 days from egg to adult, and the reproduction speed is very fast.
3. Suitable greenhouse environment
The suitable temperature for thrips is 23~28°C, and the air humidity is 40%~70%. The greenhouse environment is suitable for the growth and development of thrips. Under suitable conditions, thrips can occur for many generations, and are affected by greenhouse size and vegetable crops. Restrictions, once encountered Hummer damage, it is difficult to prevent.
4. Difficulties in drug control
Due to its small size, it has strong tropism, high fertility, short life, and various overlapping stages of insects, and the eggs are born in plant tissues. It is difficult for a medicinal agent or a spray to spray its insects. All or most of the state is killed. At present, greenhouse vegetable thrips occur severely. In many areas, the dose is increased frequently, and the number of application times is increased. As a result, the resistance of the thrips to many agents is enhanced, and the application effect is not satisfactory. The shape of the Hummer is small, and if there is no place to spray when spraying, the greenhouse environment is suitable for Hummer breeding, and soon again cause harm.
5, the symptoms are easy to cause misdiagnosis
In the birth, the plants after the damage of the thrips often show the phenomenon of leaf curling and shrinking at the top, which is easy to be confused with vegetable virus disease, leading to diagnosis errors and delays in treatment.
Fourth, comprehensive prevention and control measures
Greenhouse thrips breed quickly and become vulnerable, and should be based on prevention and comprehensive prevention.
1. Strengthen cultivation management
The use of nutrient soil seedlings, timely removal of residual diseased leaves, reduce the source of insects; timely cultivation, timely pruning, snoring, watering, eliminating underground nymphs and mites, weeding. Strengthen the management of fertilizer and water, increase the application of organic fertilizer and phosphorus and potassium fertilizer, promote the robust growth of plants, and improve the resistance of plants; covering the mulch (especially black mulch), on the one hand, can increase the ground temperature and promote the growth of seedlings, on the other hand, it can prevent Hummers go to the ground to reduce the rate of adult emergence.
2, physical control
Using the blue habit of the horse, the blue sticky board is set in the shed to trap the adult, and 21 boards per acre shed are arranged, usually hanging in a zigzag pattern every 3.6 meters, and the bottom of the sticking board is level with the top of the crop.
3, chemical control
Due to the hazard characteristics of the Hummer's nocturnal night, the application should be carried out before 10:00 in the morning, focusing on the spray, young fruit, top and tender parts to achieve a fine and even.
Root-rooting method: The seedlings were treated with imidacloprid and thiamethoxam for 1 to 2 days before planting, and 30-50 ml of each plant could control the small pest damage at the seedling stage.
Spray method: in the early stage of the disease, timely medication, 0.5% cucurbitine wettable powder 800 times solution, 20% acetamiprid solution 1000 times solution, or 60g/L ethyl spinosyn suspension agent 3000 times solution , or 22.4% spirotetral ethyl ester suspension 2000 times liquid silicone 3000 times liquid, for uniform spray application, must be fine and uniform, otherwise in the greenhouse environment, thrips grow fast, and will soon come back.
Smoke method: When the number of thrips is large, you can use dichlorvos 250g/m2 or 20% ibucarb 250g/m2. When the work is finished in the evening, the greenhouse will be sealed and the smoke will be divided into several parts. Ignite smoke.
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