Investigation And Identification Of Fungal Diseases Of American Ginseng And Study On Main Diseases Control In Liuba,Shaanxi

American ginseng(Panax quiquefolium L.)is a perennial medicinal herb in the genus Panax,Acanthaceae.It has the functions of improving immunity,reducing blood sugar and blood pressure,enhancing mental and physical strength,and has high medicinal and economic value.Since its successful introduction in the 1980s,three major eugenic bases have been formed in China,namely Fusong in Jilin,Wendeng in Shandong and Liuba in Shaanxi.With the extension of artificial planting time and the increase of planting area,the kind of fungal disease,diseased area and disease degree of American ginseng are increasing,which seriously affects the yield and quality,and becomes one of the bottleneck problems of American ginseng production.Based on the experimental demonstration base of American ginseng in Liuba,field investigation on the kinds and occurrence of fungal diseases in the main planting area of American ginseng in Liuba,reagent screening and pot incubation tests on gray mold for control effect,the effects of different soil chemical elimination methods and different soil microbial treatments on the seedlings number and yield in continuous cropping soil were carried out.The following main results have been achieved:1.Through field investigation and pathogen identification,10 fungal diseases of American ginseng in Liuba area were confirmed,including gray mold,blight,damping-off,fusarium wilt,root rot,rust rot,sclerotinia rot,black spot,powdery mildew and verticillium wilt.Gray mold is the most common and serious fungal disease in the above ground part of American ginseng.It occurs in the whole growing season of American ginseng.Mycelium type,sclerotinia type and spore type were found according to the morphology of Botrytis cinerea.Sclerotinia type is the main type.2.The mycelial growth rate method was used to measure the inhibitory effect of15 conventional fungicides on the mycelial growth of B.cinerea.The inhibitory effect of 430 g/L pentazolol,30%azole,40%benzoidamine,25 g/L fluoxonitrile and 250 g/L procyclazole was better,among which fluoxonitrile had the best effect.The EC50 was0.038μg/m L.The inhibition effect of 6 biocontrol strains on the mycelium growth of B.cinerea was measured by the plate confrontation method.Results showed that the inhibition effect of Bacillus amyloliquefaciens was the best with the inhibition rate of57.92%in petri dish.The pot experiment showed that B.amyloliquefaciens had the best control effect on gray mold and the longest duration,which had the possibility to replace traditional chemical pesticides in production.3.The effects of different soil disinfection methods and different soil microbial treatments on the number of American ginseng seedlings and yield in continuous cropping soil were investigated through a two-factor randomized plot experiment.Results showed that the seedling number and yield of American ginseng were significantly different from that of the control after soil treatment under different treatments.The treatment of Dazomet 100 g/m~2 and Actinomycete could significantly improve the seedling number and yield of American ginseng growing in continuous cropping soil.The seedling number and the yield in the control plot is 0,however the seedling number is 23 plant and the yield is 2.77 kg in the treatment.