Main Fungal Diseases And Fungicide Screening Of Buckwheat In Northwestern China

In this paper,buckwheat was taken as the research material.During the growth period of 2018-2019,the main diseases of buckwheat from seedling stage to maturity stage to harvest time in northwest China were investigated.The isolation and identification of buckwheat were carried out in the laboratory,and the following main results were obtained.1.Main diseases and their pathogens were identified.Through the isolation and purification of pathogenic fungi,pathogenicity determination,morphology and molecular identification.Seven pathogens were found: Alternaria alternata,Botrytis cinerea,B.polygoni,Bipolaris zeae,Didymella rhei,Erysiphe polygoni and Stemphylium vesicarium.2.Fungus diversity of buckwheat seeds were determined.Through the traditional isolation and culture,the seeds of different buckwheat varieties harvested in that year were tested for species and fungi,and the species and fungal flora and important pathogenic fungi of buckwheat were identified.Combined with morphology and ITS gene identification,9 genera and 11 species of fungi were isolated and identified.Respectively are: Alternaria alternate,A.brassicae,Aspergillus niger,Botrytis cinerea,Chaetomium globosum,Cladosporium cladosporioides,Epicoccum nigrum,Fusarium oxysporum,F.incarnatum,Nigrospora oryzae and Tricharina ochroleuca.The dominant fungi were Alternaria spp.,followed by B.cinerea.There was a great difference in the frequency of species fungus separation among different varieties.Among them,the lowest fungi rate of Guimiku 18 was 50%,and the rate of fungi rate was 0-100%.3.Biological characteristics and disease resistance evaluation of B.polygoni were determined.B.polygoni caused leaf spot formation in the early stage and leaf wilt in the later stage due to spot enlargement.It infects not only the leaf,but also the stem,seedling stage and growing stage.According to the biological characteristics,the most suitable medium is PSA,which has the fastest growth rate,the best utilization effect of soluble starch from carbon source and the highest utilization rate of beef extract from nitrogen source.The disease resistance evaluation of buckwheat varieties showed that five of the 20 tested buckwheat varieties with high disease resistance were selected as Dingtian 1,Dingtian 2,Guimiku-18,Yunqiao 1 and Guiqiao 2.4.Effective fungicides were screened.The inhibition effect of 7 fungicides on mycelia growth of 6 pathogenic fungi was determined by mycelia growth rate method.The results showed that Mancozeb had the best inhibitory effect on A.alternata,B.polygoni and S.vesicarium.Benzimine had the best inhibitory effect on B.zeae.The inhibitory effect of Carbendazim on B.cinerea was the best.Pyrimidine has the best inhibitory effect on D.rhei.