Ultraviolet induction and characteristics of Botryosphaeria berengriana resistant to tebuconazole

Nine tebuconazole-resistant isolates of Botryosphaeria berengriana f.sp. piricola were obtained by ultraviolet-induction from the media containing tebuconazole.The resistance ratio was from 11.00 to 67.88.The resistance ratio of most isolates decreased gradually after 9 generations of subcultures in the absence of fungicides;however isolate UV-TS1-f and UV-TS1-10 still presented high level of resistance after the subcultures.There were no significant difference between resistant and sensitive isolate in pathogenetic ability.The optimal temperature was 25-28 ℃,and the optimum pH value was 7-8 for both sensitive and resistant isolates.The effects of different carbon and nitrogen sources on the colony growth and mycelial weight were different.The results suggested that resistant isolate of B.berengriana was easily developed under the selection of tebuconazole,and the resistance risk was susceptible to produce resistant moderate or high.