苗圃中刚出土的幼苗嫩茎,由于与土壤接触,常被立枯病菌侵染,病苗茎基部缢缩变褐,或根部皮层腐烂,植株很快凋萎而枯死。此病田间蔓延迅速。严重时幼苗成片死亡,尤以高温多湿季节和秋播嫩种发病最为严重。笔者从1979年起,于夏季在柑桔苗圃用塑料薄膜覆盖.进行土壤高温消毒,不仅有效 The young stems and young stems unearthed in the nursery are often infested with the actinomycetes due to contact with the soil. The base of the diseased seedlings shrinks brown, or the root cortex decays, and the plants rapidly wilt and die. The disease spread rapidly. In severe cases, seedlings die, especially in the hot and humid season and fall seeding the most serious. The author has covered the orange nursery with plastic film in summer since 1979. It is not only effective to sterilize the soil at high temperature