1 College of Agriculture，Inner Mongolia Agricultural University，Hohhot 010019，Inner Mongolia，China； 2 Government of Datan township in Chayouzhong county，Chayouzhong 013558，Inner Mongolia，China
In order to definit a new disease observed on carrot roots and its pathogen species
of Fusarium causing carrot root rot，this paper isolated the pathogen with tissue isolation method，
inoculated the carrot slices，and carried out pathogenicity identification with morphology and
molecular biology．Pathogenicity was tested with the inoculated carrot slices，inoculated wounded
and non wounded carrots，and carrots planted in pots．The results indicated that 3 strains F1，
F2 and F3 were obtained，and all isolates appeared typical symptoms and showed pathogenicity．
The isolate F1 was identified as Fusarium oxysporum，the F2 and F3 were both identified as Fusarium solani with morphology preliminary．Sequences of ribosome rDNA-ITS of isolates were tested with primer ITS1/ITS4，
the same results were obtained with morphology，which showed the pathogens were F. oxysporum and F. solani on
carrot root rot.
