Investigation Of Potato Storage Diseases In Some Areas Of North China And Preliminary Study On Patato Dry Rot

The patato storage diseases were investigated from May 2008 to May 2009 in Chayouqian Qi, Zhangbei County, Jining area, Datong city, Wuchuan County, Zuoyun County, Youyu County. The samples were collected, the pathogens on samples were isolated, purified and identified.Four fungi diseases and three bacteria diseases of potato were found in Huabei area including Fusarium spp, Rhizoctonia solani, Phytophthora infestans, Alternaria solani, Clavibacter michiganense subsp. sepedonicus, Erwinia carotovora var. carotovora and Streptomyces scabies .Four species pathogens of potato dry rot disease were found. They were Fusarium solani var. coeruleum, Fusarium acuminatum, Fusarium sambucinum and Fusarium solani.The biological test showed that 18℃and pH 10 were optimum for mycelium growth of Fusarium solani var.coeruleum; 23℃and pH 10 were optimum for mycelium growth of Fusarium sambucinum; 25℃and pH 8 were optimum for mycelium growth of Fusarium acuminatum. Glucose were the best C sources in axenic culture of Fusarium sambucinum, Starch were the best C sources in axenic culture of Fusarium acuminatum, Starch fructose glucose and maltose of carbon sources had no obvious difference on the growth of Fusarium solani var. coeruleum.Three kinds of pathogens could not use ammonium sulfate as nitrogen source; Sodium nitrate, urea and peptone sources had no obvious difference on the growth of Fusarium sambucinum.Urea and Peptone were the best N sources in axenic culture of Fusarium acuminatum; Sodium nitrateere the best N sources in axenic culture of Fusarium solani var. coeruleum.Investigation of seven varieties of potato in the storage showed that the infection rate of Buerbanke was the lowest 6.89%,the infection rate of Dixirui was the highest 61.1%. Different types of storage pits had different effects on the potato disease incidence. Potato disease incidence in small-scale straight underground storage pit was 26.77%; incidence in small straight-type semi-underground storage pits was 40.5%; incidence in small fei-shaped semi-underground storage was 44.96%; incidence in large fei-shaped underground storage was 44.11%; incidence in large modern potato storage pit was 43.32%. Diseases development was mainly determined by the temperature and humidity.The toxicity evaluation results were obtained through laboratory test 22.2% Imazalil against three kinds of potato dry rot pathogens were the best,EC50 was minimum; average value was 0.2846μg/mL.