Baseline Sensitivity and Monitoring for the Resistance to Benomyl of Fusarium Species Causing Bakanae Disease in Korea

Hyo-Won Choi1,*   Yong Hwan Lee2   Sung Kee Hong3   Young Kee Lee1   Jae Guem Lee1   Hyo Won Kim1   

Abstract

To examine the changes in resistance to benomyl of Fusarium species causing bakanae disease, Fusarium isolates were collected in Korea, and pathogenicity tests were performed using rice seeds in vitro. Minimum inhibitory concentration (MIC) and effective concentration of 50% (EC50) values of isolates were examined using the agar dilution method. High frequency distribution of MIC values to benomyl against isolates collected in 2006~2007 and 2013~2014 years were 1.5625~3.125 μg/ mL and more than 25 μg/mL, respectively. The mean EC50 value of isolates to benomyl increased from 1.6397 μg/mL in 2006~2007 to 2.4892 μg/mL in 2013~2014. Based on MIC and EC50 values of isolates, the moderate resistance of benomyl were determined as more than 25 μg/mL of MIC and less 2.4 μg/mL of EC50 value, and resistant isolates to benomyl were determined as more than 2.4 μg/mL of EC50 value. Compared with the ratio of resistant isolates in 2006~2007, the ratio of resistance isolates in 2013~2014 increased from 12.5% to 36.4%. In addition, multiple resistant isolates to prochloraz as well as benomyl increased to 20.3% in 2013~2014.

Acknowledgements

This study was supported by a grant (Project No. PJ009891) from Rural Development Administration, Republic of Korea.

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