Identification and biological characterization of the pathogen causing brown spot on samara of Acer truncatum Bunge and screening of effective fungicides
To investigate the causal agent of samara brown spot occurred on Acer truncatum Bunge in Guiyang City,Guizhou Province,we collected diseased samara for pathogen isolation.YB26,a representative fungal strain causing the disease through pathogenicity test,was identified as Alternaria alternata based on combined results of morphological characteristics and multigene(rDNA-ITS,Alt al and GAPDH)phylogenetic analysis.Then the biological characteristics of A.alternata strain YB26 were determined by testing the mycelial growth rate under different carbon and nitrogen sources,temperatures,pH values,media and light conditions.The re-sults showed that the suitable conditions for vegetative growth of YB26 were mannitol as carbon source,beef ex-tract as nitrogen source,Sabouraud glucose agar(SDA)as culture medium,temperature of 28 ℃,pH value of 7,and incubation under darkness.Furthermore,the inhibitory effects of 7 fungicides against strain YB26 were tested,among which 25% pyrisoxazole had the best antifungal activity,with the EC50 value of 0.8323 mg•L-1.This is the first report of samara brown spot on A.truncatum caused by A.alternata.The results provide a basis for the diagnosis and control of the disease on A.truncatum.
samara of Acer truncatum Bungebrown spotAlternaria alternatabiological characteristicstoxicity test
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