Study On Biological Characters Of Sclerotium Rolfsii And Integrated Control Of Coptis Chinensis Southern Blight

Southern Blight is an important disease on Coptis chinensis in recent years. In this paper, systematic study was did on Coptis southern blight symptoms,pathogen identification, biological characteristics, integrated control methods and so on. Theoretical basis was provided for the effective prevention and treatment of this disease.1.Symptom of pathogenAugust is the most appropriate time for the southern blight, about 30% plants caught disease in the field. Mycelium was produced by sclerotia which in the soil, winding up from base of stem. Then, the site of infection emerged soaking spots, plants began to yellow, and finally dead. The mycelium resulting from red-brown mature rapeseed shaped sclerotia.2.Pathogen identification of pathogenIsolated samples was collected from Coptis southern blight diseased plant in the field, using isolates of sclerotia inoculatied on healthy plants, show the same disease symptoms. Isolated disease plant again, characteristics was the same to the previous isolates, then complete Koch-type rules. Proved that isolates is pathogen of Coptis southern blight.Plate covered with mycelium were picked under the microscope, hyphae are separated, diameter was 6.45μm. Sclerotia first white, then become yellow, and finally become dark brown, cut inside sclerotia were gray. Sclerotia spherical or irregular, smooth, shiny surface, diameter of between 0.3-0.8cm. According to morphological characteristics of pathogens, identified the pathogen of Coptis southern blight was Sclerotium rolfsii. 3.Biological characteristics of Sclerotium rolfsiiResults showed that Coptis extract 20%+PDA is the best medium for mycelial growth; mycelial could grow between pH3～10, pH7.0 was the best; mycelial growth and sclerotium germination optimum temperature is 30℃;glucose, mannitol is the best carbon source;ammonium chloride, ammonium sulfate is the best nitrogen source;lethal temperature of mycelial is 60℃,lethal temperature of sclerotia is 65℃.4.Chemical controlPharmaceutical screening results showed that effects of flusilazole, hymexazol, mancozeb on southern blight control is effectively, the proposed application in production. These agents first anti-root pouring inoculation effects are better than the first case irrigating roots after inoculation.5.Agricultural controlAgricultural control study showed in dispose of urea and ammonium bicarbonate germination rate of sclerotia was the lowest; when soil moisture is 40%, the germination rate of sclerotia, high and low humidity were not conducive to the germination of sclerotia; sclerotia can not germinate when soil deeper than 5cm.6.Biological controlUsing gradient dilution method,36 fungi were isolated from soil, through the confrontation culture, found 7 strains were better; Trichoderma viride TV-2 inhibitory effects on antagonistic substance produced was the most obviously; methanol extract the antagonistic inhibitied the growth of S. rolfsii was the most obviously; organic solvent and the fermentation liquid ratio was 1:1,blocked the growth of S. rolfsii was obviously; PD was he best medium to the production of antagonistic substances;inoculated TV-2 to Coptis plant, the incidence rate was 37.5%; TV-2 can also degrade berberine in the soil.