Therefore, considering the importance of the problems caused by false mildew in safflower in Mexico, the scarce scientific reports generated to date, the absence of reports with DNA for sequence R. cercosporelloides and the problems associated to isolation by conventional methods, the objectives of this research work were: 1) to isolate the fungus from false mildew affected safflower leaves at the Yaqui Valley, 2) to obtain their DNA sequences and, 3) to establish in vitro conditions for their optimal growth.