SUMMARYThe presence of different carbon and nitrogen sources and bivalent metal compounds in the substrate medium influenced the mycelial growth ofMacrophomina phaseolinaandin vitrosusceptibility to fungicides. The inoculum from such substrate media showed differences in pathogenicity on mung bean(Vigna radiata).Sucrose and asparagine significantly increased the mycelial growth as well as pathogenicity of the fungus. Absence of bivalent metal ions,viz., Fe++, Zn++and Mg++in the medium produced inoculum which caused maximum seedling mortality and foliage blight.Carbendazim and thiophanate‐M as seed treatments were significantly less effective when the inoculum was from a medium containing glucose than when the inoculum was from a medium containing sucrose. Captafol and thiram gave significantly better disease control on mung bean when the inoculum used for soil inoculations was from media containing asparagine and ammonium nitrate compared to the inoculum grown on a medium containing sodium nitrate. Carbendazim, thiophanate‐M, PMA, captafol and thiram gave good disease control when the inoculum used was raised on a medium devoid of bivalent metal ions. Carbendazim and thiophanate‐M were the best fungicides as foliar treatments and controlled the disease irrespective of carbon, nitrogen and bivalent metal ion status of the substrate medium used for the production of ino