The Control Of Tomato Gray Mould(Bortrytis Cinerea)by Trichoderma

The biological traits,fermentation factors, biocontrol mechanism of Trichoderma and foliage environment affecting the biocontrol activities of Trichoderma were studied systematically in laboratory chamber and greenhouse. At the same time, the influence of chemical fungicides on Trichoderma a modle for combining application of chemical and Trichoderma was also studied. Potential biocontrol isolates were screened from 28 isolates by comparing their biological activies in vitro and vivo. The five isolates had fast growth and higher inhibition to gray mould(Bortrytis cinerea). If four isolates were mixed and sprayed to tomatoes, the disease could be controlled by 75 per cent. This phenomenon proved that there was synergistic effect among Trichoderma isolates. Result showed that BTC2 1 (Trichoderma harzianum) could grow well when common sugar or heparin was as carbon source in medium. Fructose and melibiose were good for conidia production. Nitrogen had better effects on BTC2 1 growth and conidia production than carbon source. Yeast extract was the best nitrogen source for BTC2 1 fermentation from which a large amount of hyphe and conidia could be obtained. Na3PQ4 and MgSQ4 also promoted the growth of hyphae. Under the condition of carbon to nitrogen was 4:6 and pH was 5.5-6.5, Trichoderma grew well. Five to eight days of shake cultivation was good for BTC2 1 to have higher amount of dry mycelium weight and spore production. The optimal temperature for fermentation was between 22.5 to 27.5 0C. Different carbon and nitrogen could affect the spore germination. Nelibiose, yeast extract, pepton, NH4SO4, NH4C1 were all available for spore germination. BTC21 spore germination was best when temperature ranged from 20 to 300C and humidity was kept above 80 per cent. BTC16(Trichoderma aureoviride) and BTC21 had a strong ability of parasitism and could not produce antibiotic. But the activities of chitinase and j3 -1,3-glucanase were detected in the two isolates ferment filtrate and hyphae of Bortrytis cinerea degraded by Trichoderma filtrate was observed at the same time. That showed there really existed parasitism. Something which was 4ble to disturb Bortrytis cinerea polymethylgalacturonase(PMG) enzyme activity was also detected in the two isolates ferment filtrate. This phenomenon was first found in our nation. If the plants were treated with TrichQderma then challenged by Bortrytist cinerea, it was found that the biocontrol agent could induce the higher activity of defensive enzyme in tomato plants. B-esult suggested that KH2PO4 could stimulate the growth and competition of Trichoderma. The control efficiency was increased with the growth of KH2PO4 concentration. Some chemical fungicides also had some effects on Trichoderma biocontrol activity. Among the seven fungicides for experiments, Trichoderma was very sensitive to carbendazim and little sensitive to pyrimethanil and mycozob. So Trichoderma could be mixed or alternated with the last two fungicides. In green house trails, we found a good control of the disease was achieved if spraying BTC21 and Pyrimethanil to plants together as compared with single uses of them.