The goals of the present study were to determine ifCylindrocarpon olidum var.olidum exerts antibiotic activity on teliospore germination ofTilletia laevis in vitro and to evaluate the efficacy of a seed treatment with this antagonist against artificial seedborne infection in the field under natural cropping conditions. Germination of bunt teliospores was completely inhibitedin vitro on water agar medium supplemented with the antagonist’s culture filtrate. In field experiments seed application reduced the incidence of common bunt from 82.9% to 40.4%, and from 81.4% to 42.0% in 1995/1996 and 1997/1998, respectively.C. olidum var.olidum may have a potential againstT. laevis and is worthy of further research on its use as a biocontrol agent for common bunt.