黄瓜枯萎病的研究

Research on Cucumber Fusarium Wilt

黄瓜枯萎病,又名萎蔫病、蔓割病、死秧病,是一种由土壤传染、从植株根或根颈部侵入、在维管束内寄生的系统性病害(导管型枯萎病),是黄瓜生产上较难防治的病害之一,常造成较大损失。黄瓜枯萎病的病原菌为半知菌亚门镰孢菌属的尖镰孢菌黄瓜专化型(Fusarium oxysporum.sp.cucumebrium Owen)。该病菌以菌丝体、厚垣孢子和菌核在土壤、病株残体及未腐熟的农家肥中或附着在种子上越冬,成为翌年初侵染源,也可借助雨水、灌溉水等进行远距离传播。黄瓜枯萎病的防治要以预防为主,结合使用抗病品种,采取轮作倒茬或嫁接等栽培管理措施,配合处理种子与土壤及发病初期施药等化学防治方法,达到综合防治黄瓜枯萎病的目的。

Cucumber Fusarium wilt is a systemic disease（ductal type wilt） infected by soil,invaded from root or crown and parasitized in vascular bundle,which is one of the diseases difficult to control in cucumber production,and often causes great losses.Cucumber Fusarium wilt generally damages the stem base near ground,and can cause the death of the entire cucumber plant after pathogen infection.The disease can occur in various stubbles of cucumber in open fields and protected fields,which has heavy occurrence in the cucumber within greenhouse and the spring cucumber in open field,and has light occurrence in summer and autumn cucumber.The disease affects the yield and quality of cucumber under light condition,and leads to the death of the entire plant under severe condition,and currently is the major soil-borne disease in cucumber production around the world,causing great losses.In general year,the cucumber has yield reduction by 25%-35% due to the disease,and even fails to harvest in the year with heavy occurrence.The pathogen of cucumber Fusarium wilt is Fusarium oxysporum.sp.cucumebrium Owen belonging to Fusarium,Deuteromycotina.The pathogen survives the winter as mycelium,chlamydospore and sclerotia in soil,plant debris,manure has notdecomposed or attached in seeds and becomes the primary source of infection in next year.It can also spread in long distance through rain water and irrigation water.The occurrence of cucumber Fusarium wilt is related to resistance of cucumber varieties,climate,cultivation measures,underground pests and nematodes harm.When the soil temperature is 24-28 ℃,the soil moisture is relatively large and the air relative humidity is high,the incidence is fast.The aging seedlings,continuous cropping fields,not decomposed organic manure,too dry soil or poor drainage,acidic soil,and serious damage of underground pests and nematodes are facilitated for the incidence.The cucumber can have the incidence throughout the whole growth period,and the incidence from flowering and vining stage to fruiting stage is the greatest,the duration form occurrence of wilting to the death of entire plant is 7-10 d.In initial stage of infection,the plants are withered at noon,and return to normal in morning,evening and night,and the entire plants die after repetition for a few days.When the plants are infected during seedling stage,the stem base will be brown and constricted,and lodged to die under severe condition.In the initial incidence period during adult stage,the middle and lower leaves have chlorotic leaf vein,with occurrence of meshy yellow mark;when the stem is infected,the stem vine is watermark,the base and node are faded and softened;when the root is infected,the growth point is under dehydration state,and new roots can not be germinated,causing rotten root.In the late stage of incidence,the stem base has longitudinal crack,and amber rosin colloid are often flowed out,the stem base and root are gradually become brown and rot,which are easy to uproot from soil.When the soil humidity is large,white villous or pink mycophenolate layer is produced incrown and leaves,namely mycelium and conidium of the pathogen.When the diseased stem is cut horizontally,it can be observed that the vascular bundle is yellowish brown to dark brown,sometimes few colloids are overflowed from the diseased part,this is the important characteristic of cucumber Fusarium wilt.Because cucumber Fusarium wilt can infect from seedling stage to maturity stage,it is difficult to be radically controlled.Therefore,we should give priority to prevention,combine with the utilization of resistant varieties,adopt the cultivation and management measures such as crop rotation or grafting,and carry out chemical control method such as seeds and soil treatment and pesticide application in initial incidence stage,so as to achieve the purpose of comprehensive control of cucumber Fusarium wilt.