To determine the sensitivity of southern corn leaf blight pathogen Cochliobolus heterostrophus to fluazinam, and evaluate the cross-resistance between fluazinam and other fungicides, a total of 73 C. heterostrophus isolates collected from five regions in Fujian Province were used for testing their sensitivity to fluazinam using mycelial growth method. The tested isolates were highly sensitive to fluazinam, and the EC50 of these isolates to fluazinam were in the range of 0.0023-1.2863 μg/mL, with the mean value of 0.2573 μg/mL. The frequency curve of fluazinam was continuous and unimodal, and followed the normal distribution. Hence, the mean EC50 of 0.2573 μg/mL could be served as the baseline sensitivity of C. heterostrophus to fluazinam in Fujian Province. There was no significant difference in the sensitivity to fluazinam among C. heterostrophus populations from five regions; nevertheless, there was an obvious difference in the sensitivity to fluazinam among individual isolate from different regions in Fujian Province. There was no notable evidence of positive cross-resistance between fluazinam and carbendazol, chlorothalonil, propiconazole, diniconazole, prochloraz, and iprodione.
Acta Phytophylacica Sinica