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1大棚蔬菜病虫害的特点1.1土壤对病虫害发生的影响及防治对策土壤中的病原菌和大量的有益微生物不一定平衡,但由于蔬菜根系的分泌物质和病根的残留,土壤微生物逐渐失去平衡,病原菌数量不断增加,诱使病害发生。棚室土壤比露地土壤光照少,温度和湿度高,病源增殖迅速,生产中又缺乏抗病品种,这就使得土传根病随连作年限增多而加重,如新建棚室发生瓜类枯萎病后不及时采取效防治措施,一般从零星病株到普遍发病只需4～5年时间,果菜类根结线虫病只需3～4年,病株可达
1 Greenhouse pests and diseases characteristics of vegetables 1.1 The impact of soil on pests and diseases and prevention and control measures Pathogenic bacteria in the soil and a large number of beneficial microorganisms are not necessarily balanced, but due to the secretion of vegetable roots and root causes of residue, soil microorganisms gradually out of balance, the number of pathogens continue Increase, induce disease. The greenhouse soil had less light than the open soil, high temperature and humidity, rapid multiplication of pathogen, and lack of disease-resistant varieties in production. This made soil-born root-knot disease aggravate with continuous cropping years. For example, Not timely take effective prevention and control measures, generally from sporadic disease to the general incidence of only 4 to 5 years time, fruit and vegetable root-knot nematode disease only 3 to 4 years, the disease strains up