Decreased sensitivity of Fusarium fujikuroi Nirenberg isolates from Hyogo Prefecture to Pefurazoate

Abstract

We obtained 434 isolates of Fusarium fujikuroi Nirenberg collected from Hyogo Prefecture and examined their sensitivity to pefurazoate (Pf) and ipconazole (Ip). The minimum inhibitory concentration range profiles in sensitivity to Pf and Ip were from 0.78 μg/mL to 12.5 μg/mL and from 0.39 μg/mL to 1.57 μg/mL, respectively. The efficacy of seed treatment with Pf and Ip against rice Bakanae disease was evaluated using a seedling test with inoculated seeds. The treatment with the mixture of Pf, fludioxonil, and copper oxychloride, and the mixture of Ip-copper hydroxide flowable, showed high efficacy (protective values were larger than 96.0). In contrast, the treatment with the emulsion of Pf showed low efficacy (protective values were less than 90.0) in 7 out of 12 isolates. These results indicated that the sensitivity of some F. fujikuroi isolates to Pf decreased in the Hyogo Prefecture.