| Sclerotinia sclerotiorum（Lib.）De Bary is a plant pathogenic fungus widely distributed in the world.When Sclerotinia sclerotiorum infects plants,it causes sclerotinia disease of all kinds of crops and causes great damage to crops.S.sclerotiorum is one of the main diseases in rape production in China.It can occur in all rape producing areas in China,which has a serious impact on the yield and quality of rape.At present,chemical control is the main means to control the disease,but due to the long-term continuous use of chemical agents,the control effect of Fungicides on S.sclerotiorum of rape gradually decreases.Therefore,it is very important to select appropriate chemicals to control Sclerotinia sclerotiorum.In this study,93 strains of S.sclerotiorum were isolated from Huangshan,Wuhu,Hefei,Fuyang and Yancheng;determination of the acid-producing ability of the tested strains and the pathogenicity of some strains;The mycelial growth inhibition method was used to determine the EC50 of prochloraz,pyraclostrobin,sclerotiorum and tebuconazole to the isolated strains,and to establish the relative sensitivity baseline of Sclerotinia sclerotiorum to the above four fungicide.（1）The average growth rates of S.sclerotiorum strains in Huangshan,Wuhu,Hefei,Fuyang and Yancheng were 2.08,2.00,2.04,2.01 and 2.01 cm/d,respectively.There was no significant difference in colony morphology and growth rate among the five regions.All strains produced sclerotia at the edge of the colony with little difference in shape and size.The average 100-grain weights of Huangshan,Wuhu,Hefei,Fuyang and Yancheng strains were 0.71,0.72,0.86,0.91 and 0.80 g.And all the 93 tested strains had the ability to produce acid.（2）The pathogenicity of isolates from different regions was determined.The pathogenicity of isolates from different regions was different,and the average diameter of diseased spots of isolates from Huangshan and Hefei regions was larger than that from other regions.（3）S.sclerotiorum isolates from 5 regions had some differences in their sensitivity to prochloraz.Among them,the average EC50 values of prochloraz to Huangshan and Hefei strains were 0.0296 mg/L and 0.0274 mg/L,respectively.The sensitivity of strains in these two regions to prochloraz was significantly different compared with other regions.The average EC50 value of prochloraz for the strains in these five regions was 0.025±0.007 mg/L,which could be used as a reference value for the baseline sensitivity of S.sclerotiorum to prochloraz in these regions.（4）The average EC50 of pyraclostrobin to the tested strains isolated from 5 regions was0.185±0.068 mg/L.The sensitivity of S.sclerotiorum to pyraclostrobin was different in different regions,and the EC50 value of the least sensitive strain was 6.09 times that of the most sensitive strain.（5）The distribution range of EC50of dimethachlon to the tested strains isolated from 5regions was between 0.198-0.334 mg/L,with an average value of 0.284±0.027 mg/L.There was no significant difference in the sensitivity of strains to S.sclerotiorum from different regions.（6）The distribution range of EC50 of tebuconazole against the tested strains isolated from5 regions was 0.117-0.407 mg/L,with an average value of 0.225±0.052 mg/L.There are some differences in the sensitivity of strains to tebuconazole in different regions. |
