| China is the largest producer of Lentinula edodes around the world. L.edodes is cultivated widely in China and holds an important position of the edible fungi industry. L.edodes cultivation bag rot disease which was found by our research group occurred seriously in Suizhou, Hubei province. The disease occurred after the first flush during the temperature increasing which was different from commom Trichoderma contamination during mycelia stage.Cultivation bag rot was investigated systemicly in Suizhou in the study, at the same time samples collection were performed in Biyang, Xixia, Sanmenxia, Pingnan, Minqing, Youxi, Lishui, Jingning, Qingyuan. 58 isolates were isolated and purified from 133 samples. The isolates were identified into 6 Trichoderma species. Characteristics of some isolates were measured. The effects of different gypsum powder content, pricking frequency and moisturing time and method on the incidence rate of the rot disease were studied systematically. The pathogenicity of 6 Trichoderma species to 4 L.edodes strains was tested during L.edodes strains’ colour turning period.The number of T.harzianum, T.atroviride, T.viride, T.pleuroticola, T.longibrachiatum and T.oblongisporum of the identification result was 38, 4, 6, 4, 3 and 3. The Trichoderma strains distributed in L.edodes cultinated areas of 4 provinces and T.harzianum was the dominant species. Characteristics differences existed among the isolates at different temperature and p H on CYM medium. The optical temperature of most Trichoderma isolates was 25℃, but a few isolates were 30℃. 18 of the 24 testing isolates could survive at 35℃.The resistence of L.edodes to Trichoderma were different on differen culture substances.The inhibition rate of T.harzianum(T12, T28, T2, T48),T.atroviride(T29, T24),T.viride(T25,T52,T55),T.pleuroticola(T22,T35,T39),T.longibrachiatum(T33) and T.oblongisporum(T37) to L.edodes(Qiu7) was different. The inhibition rate of T.harzianum, T.viride and T.atroviride was between 63% and 94%, T.longibrachiatum had the lowest inhibition rate 29%. The two T.atroviride isolates had a large diffenrence regarding the inhibition rate which was 73%(T29) and 50%(T24). Cultivated on the sawdust substrate in glass tube, L.edodes(Qiu 7) had strong resistance to the 6 species of Trichoderma, antagonistic treaks appeared apparently between them, Trichoderma could not spread over L.edodes. During the L.edodes colour turning period, 44 kinds of combination of 11 Trichoderma and 4 L.edodes strais showed that only 6 kinds of combination appeared pathogenicity, the results above revealed that Trichoderma species had weak pathogenicity to L.edodes under normal cultivation conditions.30% fermentation broth of T.harzianum(T36) had no significant inhibition to L.edodes, but the inhibition of 30% fermentation broth of T.oblongisporum was above 60%. On the medium containing fermentation broth of T.oblongisporum under scanning electron microscope, unormal phenomenon of L.edodes mycelia was observed: becoming thicker, twisting, rupturing and shriveling. It indicated that Trichoderma could inhibite the growth of L.edodes mycelia by secreting secondary metabolites.According to the results, there was no significant revalance between disease incidence rate and gypsum content, pricking frequency and moisturing time and method. However it had a positive correlation with temperature during the mycelia stage, when inoculated earlier had higher temperature than later.The results of the study showed that L.edodes mycelia cultivated in sawdust substrate could tolerate high temperature stress for a short time(37℃for 6h), but the resistance ability would drop significantly with the passage of time. The mycelia of L.edodes grew faster after high temperature stress. It indicated that high temperature stress could lead to the decline of the resistance of L.edodes to Trichoderma. But the stress was reversible, the mycelia could recover when the contention was suitable. To manage the erupting of the disease, arranging the inoculation time appropriately and ventilating and cooling timely were required during L.edodes cultivation. |
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