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Planting vegetables in greenhouses should pay attention to the influence of "four pests"
In addition to the varieties of greenhouse vegetable cultivation is not the road, but also pay attention to the "four evils" of the impact, that is, fertilizer damage, injury, drought and other obstacles. Fat damage. In fact, it is the hazard of salt accumulation. The main reason is that partial application of chemical fertilizer or excessive fertilization will cause soil salinization. After the occurrence of fertilizer damage, the first problem is to inhibit the development of vegetable roots, weakening the absorption of water and fertilizers; second, the concentration of soil solution is too large, the vegetable plant body reverse osmosis phenomenon, leading to physiological wilting or leaf margin Jiao Jiao; Is the introduction of toxic gas hazards; Fourth, causing vegetable deficiencies. Phytotoxicity. There are obvious phytotoxicity and symptoms are obvious. There are hidden phytotoxicity, symptoms lurking or extending to squat vegetables. The reasons for the occurrence of phytotoxicity are: first, the selection of pesticide species is not the right way or the misuse of herbicides; second, the application concentration is too large; third, the use of inferior pesticides; and (4) the application of high temperature seasons is not avoided. After the occurrence of phytotoxicity, some vegetable leaves soon become chlorogenic; some produce focal spots and perforations; some have fallen leaves, fallen flowers, fallen fruits, or are deformed; the most severe whole plants wither. Drought damage. It is one of the most critical factors that restrict the development of greenhouse vegetables. The reasons for this are the improper location of vegetable greenhouses and the lack of water resources in the local area. Second, there is water, but the water quality is poor. Third, the amount of water is more than enough, and the ditch, canal, irrigation and drainage facilities are not matched, and water is difficult to attract. Drought damage not only affects the timely sowing of vegetables and seedlings, but also affects the normal growth of vegetables. At the same time, it brings great difficulties to the management of vegetables such as fertilization and pesticide application. The effects of droughts sometimes exceed those of fertilizer and phytotoxicity. Even obstacles. In the same greenhouse, the same or similar vegetables are planted year after year or season, and the yield and product quality are declining year by year. The reasons for the obstacles are: First, the same or similar vegetables prefer a certain kind of nutrient elements; the supplementation of such elements is not timely prone to deficiency of the disease; second, the accumulation of soil pathogens causes disease caused by dead seedlings, such as wilt disease and yellow wilt; Third, the secretion of root vegetables in the same vegetable can easily lead to loss of balance in the soil microbial community structure and cause soil degradation.