Study On The Pathogen Of The Leaf Blight Disease Of Lycium

Through investigation and study of the leaf blight disease of Lycium in 5 different areas in Mongolia, the pathogen was identified in-house as Alternaria tenuis Nees, biological characteristics of the pathogens, the bioassay of toxins from A. tenuis Nees, the pathogenic mechanism of toxin and the toxicity determination of the fungicide were studied. The results showed that A. tenuis Nees could grow in 5-35℃ and the optimum grown temperature was 25℃. The range of pH value was 3-10,the optimum pH value was 7-8.The different light treatment had no obvious effect on the grown of the fungi. Glucose, starch, peptone, glutamic acid, NH4NO3 were the best C and N sources in axenic culture of the pathogen. The relative humidity for spores germination was 50%-100%,but the optimum relative humidity was more than 90%.The spore could germinate in 5-35℃,the optimum temperature was 25℃.The bioassay of toxin used seeding and young leaves because it could cause the evident symptom rapidly and sensitively. The toxin produced by A, tenuis Nees could change the function of the toxin on the POD, SOD and PAL was identical to A. tenuis Nees. The toxicity determination of the fungicide showed Dithane M-45, Junhejing, Thiophanate-methyl had better controlling effects to A. tenuis Nees.