Abstract BACKGROUND: Fusarium head blight caused by Gibberella zeae is an important disease of wheat and barley because it reduces grain yield and quality and results in the contamination of grain with mycotoxins. Recent studies have shown that carbendazim resistance in field strains of G. zeae is not caused by mutation of the β‐tubulin gene (β 1 tub ), which is the case with other filamentous fungi, but that fungicide resistance is greatly increased by deletion of β 1 tub . The aim of the present study was to clarify the function of β 1 tub and its role in carbendazim resistance in G. zeae by artificial gene operation. RESULTS: Deletion of β 1 tub reduced vegetative growth and pathogenicity but increased asexual reproduction in G. zeae . All the mutants were more resistant to carbendazim than parent strains. A three‐dimensional model of β 1 tub was constructed, and the possible carbendazim binding site was analysed. CONCLUSION: β 1 tub is not an essential gene in G. zeae , but it affects the sensitivity of the fungus to carbendazim. Copyright © 2012 Society of Chemical Industry