SUMMARYUnder a glasshouse crop of red clover,Ophiobolus graminis(Sacc.) Sacc. in artificially colonized straws survived for longer on the soil surface than when buried, and for much longer when suspended above the soil; survival in buried straws was somewhat more prolonged in fallow soil than under clover. In field experiments with consecutive crops of winter wheat, under‐sowing with red clover was not effective in reducing the incidence of take‐all, possibly because of above‐ground survival of the pathogen in unploughed straw. Early rotavation, however, significantly reduced disease incidence, probably because of enhanced microbial activity and competition for nitrogen in the well‐aerated compost of soil and