There are a variety of situations in which Trichoderma species have caused economic losses in mushroom production worldwide. Komatsu (1976) details studies on Hypocrea, Trichoderma, and allied fungi that are antagonistic to shiitake (Lentinus edodes). Tokimoto (1982) reports that chitinolytic enzymes produced by T . harzianum were responsible for shiitake crop failures in Japan. Liao (1985) in China deals with the efficacy of fungicides in controlling Trichoderma in sawdust cultivation of shiitake. Yoshida and Takao (1982) report that T . viride was the predominant weed mould in the culture of Pholiota nameko on rice bran in Japan. In Belgium, several Trichoderma species are reported as weed moulds of Pleurotus (Lelley, 1987; Poppe et al., 1985). Lelley (1987) records T . hamatum as more damaging to Pleurotus culture than to Agaricus. Shandilya and Guleria (1984) described Trichoderma spp. causing losses in A. bitorquis crops in India.