玉米茎基腐病的研究

玉米茎基腐病是由病原菌复合侵染所引起的病害,在山西省分布广、危害重,是玉米的主要病害之一。此病可以危害幼苗,但主要发生在生长后期。其症状分急性型和慢性型,前者整株很快青枯死亡:后者一般在吐丝后发病,较常见,一般表现为:叶片由下向上逐渐枯死,发病后期茎基纵剖面髓部变色收缩,果穗下垂,易倒伏。经试验证明:其主病原(uajor pathogen)为串珠镰刀菌(Fusarium moniliforme)、串珠胶孢变种(F. moniliforme var.subglutinans)、禾谷镰刀菌(F. graminearum)、长蠕孢菌(Helminthosporiumsp.),其中串珠镰刀菌致病力最强。通过玉米不同发育阶段的连续分离证明:四种主病原都有潜伏侵染现象,串珠可以扩展到茎基第三节间,但并不扩展到穗部。次病原(Minor pathogen为木贼镰刀菌(F. equiseti)、交链孢菌(Alternaria spp)、半裸镰刀菌(F. semitectum)、多隔镰刀菌(F. decemcellulare)、弯角镰刀菌(F. camptoceras)等,它们是在主病原侵入后才侵入寄主的,本身致病力弱,但与某些主病原有协生作用,可加重病害的发生。

Studies on Pathogens and Infoction of Corn Stalk Root Rot

Stalk root rot of corn is a disease caused by a complex of pathogens. In Shanxi province, this disease distributes widely and harms severely. It has been a major disease of corn. Although this disease can harms Seedling of corn, it mainly do the plant after tasselling. Its symptom is divided into two types:swift type and slow type. The former shows that the leaves and the stalks of infected plants become blue-withered and will die in 2-3 days.The later usually becomes obvious after tasselling, especially after flowing stage. Leaves of infected plant gradualy die from lower part to top、In the past period, when the diseased stalk base is split open, ashgray to black, shredded pith is obseaved it is interlaced with abundant grayish-red persistent hyphae. The stalk lodges easily and the ear droops down. Fusarium moniliforme, Fusarium graminearum, F. moniliforme var.subglutinans and Helmintosporium sp. are regarded as the major stalk root rot pathogens and F. equiseti, F. semitectum, F. camptoceras, Alternaria ssp. at. as minor pathogens. Major pathgens can intrude the plant from root before tasslling, i. e. repressed-infection. F. moniliforme can spread into the third internodal not to belong systemic infection. Minor pathogens intrude the plant after major pathogens do. Although their pathogenecity is very weak, togther with major pathogens will cause more severe stalk root rot. In this paper, preventio of this disease and identification of some Fusarium species are introduced.