Pathogendetection,carbonmetabolicphenotypeanalysisof<italic>Rhizopusoryzae</italic>fromtobaccoanditssensitivitytosevenfungicides

Pathogen detection of Rhizopus oryzae, which causes tobacco pole rot, was conducted using tissue isolation method. The carbon metabolic phenotype of the pathogen was studied with Biolog FF microplate. The sensitivity of R. oryzae to seven different fungicides (carbendazim, iprodione, prochloraz, flusilazole, propiconazole, difenoconazole and azoxystrobin) was also evaluated. Results showed that the detection ratios of R. oryzae from samples of tobacco leaves, tobacco baking stick and tobacco baking rope were all 100%. The numbers of carbon for metabolization and sporulation of R. oryzae were 66 and 30, respectively, which included ribitol, D-arabitol, ß-cyclodextrin, etc. While for no-metabolization and no-sporulation carbons, the numbers were 29 and 65, respectively, which included α-cyclodextrin, L-trehalose, D-galacturonic acid, etc. All the seven fungicides showed different inhibitory activities against the mycelial growth of R. oryzae. Highest sensitivities were detected when flusilazole and difenoconazole were applied, with EC₅₀ values of 8.31and 9.71 mg/L, respectively. And EC₅₀ values of propiconazole, iprodione and prochloraz were 14.24, 32.84 and > 10 mg/L, respectively. While carbendazim and azoxystrobin have the lowest activities with the EC₅₀ values > 100 mg/L. Results of this study provided reference and basis for the chemical control of tobacco pole rot.