Identification of pathogenicity and fungicide resistance of Botrytis cinerea on rose in Yunnan

【Objective】 Identified the pathogenicity and fungicide resistance of Botrytis cinerea strains from cut roses in Yunnan,and provided the basis for effective prevention and control of B. cinerea in rose production.【Method】 Strains of B. cinerea were isolated from 15 main rose cut flower producing areas in Yunnan by single spore isolation method. The spore suspension was inoculated on the complete petals of rose cultivar Pink Snow Mountain non-invasively. The pathogenicity of different strains of B. cinerea was identified by measuring the area of petal lesion. The mycelium was inoculated in PSA medium with different fungicides to control B. cinerea. Through the calculation of mycelial growth inhibition rate(antibacterial rate),the resistance of B. cinerea to thiophanate methyl,procymidone,dinitroxazole,pyrazoxystrobin,picrylamide,azoxycycline and pyrthifenamide was identified.【Result】 A total of 141 isolates collected from 15 main rose producing areas in Yunnan were determined to be Botrytis spp. according to the field symptoms,morphological characteristics and microcharacteristics of cut rose. There were obvious differences in pathogenicity among different strains of B. cinerea,with the lesion area of 3.10-781.50 mm². No completely non-pathogenic strains were detected,and a few weak pathogenic strains were detected. There was no obvious difference in the pathogenicity of B.cinerea strains from different cut flower producing areas. The sensitivity of B. cinerea to seven main fungicides for controlling B. cinerea were as follows:pyridoxazole(pyridoxazoline)>pyrazoxystrobin(methoxyacrylate)>pyrimethanil(anilinopyrimidine)>pichianilamide(nicotinamide)>procymidone(diformylimine)>pyrthiazolamide(amide)>thiophanate methyl(benzimidazole). Inhibition effects of pyridoxazole,pyrazoxystrobin and pyrimethanil were the best,the inhibition rates of mycelium growth were 95.49%,85.78% and 77.70% respectively. Followed by pichianilamide and procymidone,the inhibition rates of mycelium growth were 69.73% and 64.37% respectively. The inhibition effects of pyrthiazolamide and thiophanate methyl were the worst,the inhibition rates of mycelium growth were 44.36% and 56.16% respectively.【Conclusion】 The pathogenic difference B. cinerea strains on cut rose in Yunnan is obvious. The pathogenicity of B. cinerea on cut rose in Yunnan is not related to the place where the strain was collected. Pichiazole,pyrazoxystrobin and pyrimethanil can be used as the main fungicides to control Botrytis cinerea in cut rose production in Yunnan.