The use of cultures of Sclerotinia minor for selective isolation and enumeration of mycoparasitic isolates of Trichoderma from soil and roots

Selective isolation from soil of mycoparasites of Sclerotinia minor by bait ing with mature cultures of the pathogen was compared with the use of a sem i-selective, antibiotic-containing medium. Baiting was useful for selective ly isolating and determining the concentration in soil of a potential bioco ntrol agent such as Trichoderma virens. The method proved to be useful for enumerating T. virens on roots of sunflower and showed promise for studies of the ecology of biocontrol agents added to soil or seed.