Disease Control / Moyens de lutte Biological control of fusarium head blight of wheat with Clonostachys rosea strain ACM941

Fusarium head blight (FHB), caused by Gibberella zeae, is a devastating disease of wheat. A strain of Clonostachys rosea, ACM941 (American Type Culture Collection ATCC 74447), was evaluated for antibiosis against G. zeae in vitro and for control of FHB under greenhouse and field conditions in comparison to the registered fungicide Folicur (tebuconazole). Strain ACM941 reduced mycelial growth of the pathogen by 52.6% in dual-culture after 6 days and completely suppressed spore germination for 6 h when cocultured with a macroconidial suspension of G. zeae. Strain ACM941 reduced G. zeae perithecial production by more than 99% in a leaf disk assay, 60%–77% on infected corn kernels, and 32%–57% on spikelet debris in the field. These effects were significant (P < 0.05) and not statistically different from those produced by tebuconazole. When strain ACM941 was sprayed onto wheat heads 2 days prior to inoculation with G. zeae, it significantly reduced infected spikelets (IS) by 64% and Fusarium-damaged kernels (FDK) by 65% in greenhouse experiments. Under simulated disease epidemic conditions during 2005–2007, strain ACM941 reduced the FHB index by 58%, IS by 46%, FDK by 49%, and deoxynivalenol (DON) in kernels by 21%. These effects were significant but lesser in magnitude than those achieved by tebuconazole, which reduced FHB index by 97%, IS by 82%, FDK by 73%, and DON by 62%. Results from this research suggest that strain ACM941 of C. rosea is a promising biocontrol agent against G. zeae and may be used as a control measure in an integrated FHB management program.