Comparison of Antagonists ofSclerotiniaSpecies

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Abstract
Eight reported antagonists of Sclerotinia spp. were evaluated for their ability to destroy sclerotia of Sclerotinia minor in soil. When sclerotia of S. minor were soaked in concentrated spore suspensions of the antagonists for 3 hr and added to moist natural soil, Teratosperma oligocladum caused a 94% reduction in the inoculum density of S. minor within 10 wk. Dictyosporium elegans and Coniothyrium minitans were intermediate in reducing the number of sclerotia after 30 wk, whereas Penicillium cirtinum, Talaromyces flavus, a Trichoderma sp., and Gliocladium virens were ineffective. When sclerotia of Sclerotinia sclerotiorum were soaked in concentrated spore suspensions of the antagonists for 3 days and then added to moist natural soil infested with sclerotia of S. minor, only T. oligocladum reduced the inoculum density of S. minor. When various concentrations so spores of the antagonists were added to moist natural soil infested with sclerotia of S. minor, only Sporidesmium sclerotivorum and T. oligocladum reduced the inoculum density of S. minor. These two mycoparasites were effective at rates of 10-14 spores per gram of soil, whereas the other antagonists were ineffective at rates as high as 106-107 spores per gram of soil. It was concluded that S. sclerotivorum and T. oligocladum are aggressive mycoparasites, whereas the other antagonists are passive mycoparasites.