Studies Of Contaminative Fungi In The Substituted Cultivation Of Pleurotus Ostreatus And Lentinus Edodes

The substrate fungal contamination was researched in the substitute cultivation of Pleurotus ostreatus and Lentinus edodes from March 2002 to February 2003 in Yaan, Sichuan. The contaminative fungi were isolated respectively in the polluted cultivation substrate of Pleurotus ostreatus and Lentinus edodes. The results of identification indicated that in the substitute cultivation of Pleurotus ostreatus, the most predominant contaminative fungi was Gliocladium spp., the isolation frequency of which was 57.62%, other important fungi were Trichoderma spp., Penicillium spp., Aspergillus spp., Chaetomium spp., Rhizopus spp., Mucor spp. as well as some unidentified fungi, their isolation frequencies were respectively 10.32%, 7.85%, 4.41%, 3.72%, 2.79%, 1.52% and 11.22%. And among the total 42 Trichoderma spp isolates, 21 isolates were T. longibrachiatum, others belonged to T. harzianum, T. viride, T. citrinoviride and T. aureoviride. However, in the substitute cultivation of Lentinus edodes, the most predominant contaminative fungi was Trichoderma spp., the isolation frequency of which was 74.11%, other important fungi were Mucor spp., Monilia spp., Rhizopus spp., Verticillium spp., Aspergillus spp., Fusarium spp. and some unidentified fungi , their isolation frequencies were respectively 7.14%, 6.59%, 4.08%, 1.36%, 0.74%, 0.53% and 5.45%. And among the total 296 Trichoderma spp. isolates which isolated from the cultivation of Lentinus edodes, 265 isolates were T. harzianum, 19 isolates were T. viride, others belonged to T.koningii, T. longibrachiatum, T. aureoviride and T. hamatum.The growth rates of three strains of Trichoderma spp. and two strains of Gliocladium spp., selected from the most predominant contaminative fungi, had been compared with those of Pleurotus ostreatus and Lentinus edodes at different temperature and pH. The results showed that Trichoderma spp. and Gliocladium spp. suited to grow at higher temperature (25℃-30℃) and lower pH (pH5), and the hyphal growth rates of Trichoderma spp. and Gliocladium spp. decreased sharply as the temperature went down to 20℃ or the pH got up to pH9, but the hyphal growth rates of Pleurotus ostreatus and Lentinus edodes didn't change very much. In dual culture, Gliocladium spp. and T. viridecould overrun the colonies of Pleurotus ostreatus, T. harzianum and T. viride could overrun the colonies ofLentinus edodes.The inhibitory effects of 5 common environmental friendly fungicides (Carbendazim, Prochloraz, Thiophanate-methyl, Mancozeb and Polyoxin) on Trichoderma spp., Gliocladium spp., Pleurotus ostreatus and Lentinus edodes were tested. The results demonstrated that Carbendazim 25mg/l strongly inhibited the hyphal growth of T. viride, T.longibrachiatum and Gliocladium spp., and Prochloraz 0.25 mg/l strongly inhibited the hyphal growth of T. hamatum, T. longibrachiatum and Gliocladium spp.. Furthermore, Prochloraz 1mg/l strongly inhibited spore germination of T.hamatum, T.longibrachiatum and Gliocladium spp., the inhibitory rates of spore germination were more than 94%. However, Carbendazim 25 mg/l and Prochloraz 0.25 mg/l hardly inhibited the hyphal growth of Pleurotus ostreatus and Lentinus edodes .