Discovery Of New Diseases And Survey Of Fungal Diseases On Main Leafy Vegetables

Because of the unique characteristics,such as high nutritive value,short growth period,leafy vegetables have become the preferred choice of vegetables in the most areas to solve the self-supply of vegetables.However,the existence of high cultivation density,high humid environment,continuous cropping and other factors,the field diseases are terribly ubiquitous,which seriously restricts the sustainable development of leafy vegetable industry in China.During 2014-2016 period,the field disease investigation and specimen collection were widely carried out in the main planting areas of leafy vegetables in China.Through the identification of pathogens,the main diseases and corresponding pathogen types of leafy vegetables were identified.The main results were as follows:1.The disease survey was carried out in the main planting areas of the leafy vegetables in 46 regions of 17 provinces,such as Hebei,Gansu,Sichuan,Guangxi and Shanghai.A total of 254 samples of leafy vegetable were collected,including 39 kinds of vegetables in 11 families,such as Cruciferae,Umbelliferae,Compositae and Lilaceae.During the investigation,15 leaf diseases and 6 root diseases were found.Among them,black spot and stem rot on Cruciferous vegetables,grey mould,leaf spot and spot blight on Umbelliferae vegetables,downy mildew,sclerotinia rot and Alternaria leaf spot on Compositae vegetables were serious.Downy mildew on onion,basal stem rot on water spinach and cabbage and sclerotinia rot on lettuce tended to break out particularly.2.By morphological and molecular identification,combined with the pathogenicity test,one new recorded host disease was firstly discovered in the world,namely grey mould on water dropwort caused by Botrytis cinerea Pers.Three new recorded host diseases,namely Boeremia leaf spot on lettuce caused by Boeremia exigua(Desm)Aveskamp Gruyter & Verkley,basal stem rot on water spinach and Chinese chives caused by Rhizoctonia solani Kühn,were initially discovered in China.3.Eleven serious diseases were investigated and a total of 10 pathogens were identified,belonging to 9 different genera.Among them,three species,Peronospora destructor(Berk.)Casp.Ex Berk,B.lactucae Regel,Albugo candida Pers,each belonging to Peronospora,Bremia,Albugo Roussel ex Grey of Ophiopogon correspondingly were identified.Five species,R.solani Kühn,Alternaria brassicae(Berk.)Sacc.,Alternaria burnsii Uppal,Patel & Kamat,Stemphylium botryosum Wallr.,Cercospora apii Fresen.,belongting to Rhizoctonia,Alternaria,Stemphylium,Cercospora of Hyphomycetes correspondingly were identified.One species,Sclerotinia sclerotiorum(Lib.)de Bary,belonging to Sclerotinia in Hyphomycetes was identified.One species,Septoria apiicola Speg,belonging to Septoria in Discomycetes was identified.In this study,through the systematic investigation of the fungal diseases in main leafy vegetables-producing areas in China,the disease types and their distribution were well learned.The classification of pathogens was made clear simultaneously.It is essential to establish the pathogenic fungi repository.