Effect of carbendazim-8-oxyquinoline-copper, a novel chelate fungicide against Fusarium graminearum

Abstract

The efficacy of carbendazim-8-oxyquinoline-copper (BCOC), which is a chelate of carbendazim (MBC) and oxine-copper (BHC), was compared with that of MBC and BHC for control of Fusarium graminearum. In vitro inhibition of MBC-resistant (MBC^R) strains was greater with BCOC than with MBC or BHC, or the mixture of MBC and BHC; the minimum inhibitory concentration (MIC) of MBC-high-resistant strains for BCOC was 10 times lower than the MIC for MBC. Appearance of germ tubes of F. graminearum was similar after treating with BCOC or MBC. The EC₅₀ of BCOC was 1.29±0.61 μg/mL against 124 F. graminearum field strains collected in 2010 and 3.23±0.41 μg/mL against 127 F. graminearum MBC^R field strains collected between 2000 and 2010. BCOC provided best protective and curative control of Fusarium head blight on wheat artificially inoculated with both MBC^S (MBC sensitive) and MBC^R strains in the field. To explain the high efficacy of BCOC, we hypothesize that the 8-oxyquinoline-copper in BCOC changes the molecule's structure and thereby increases the interaction between the carbendazim radical in BCOC and the β₂-tubulin protein in F. graminearum. BCOC has substantial potential for the synthesis of new fungicides for disease control and resistance management.