SUMMARYIn experiments on the control ofMycogone perniciosathere was a good relationship between yield, disease incidence and the rate of benomyl applied to the casing. Casing treatment controlled the disease irrespective of time of inoculation. Benomyl controlled the disease in all experiments and good results were also achieved with thiophanate methyl and to a lesser extent with thiabendazole. Bioassay of sporophores showed the presence of an inhibitory substance from benomyl and thiophanate methyl treatments even after 6 wk of cropping.