[The effect of Some Fungicides on Trichoderma spp. That use in Biocontrol]

The effects of 10 fungicides from different chemical groups have been studied on three fungus isolates of Trichoderma spp., which used in biological control, two of them are local isolates (T1 and T5) obtained from Syrian coastal soils, and the third is commercial (Tbio). The three studied Trichoderma isolates (whether commercial or local ones) showed a high competitive efficiency, as they inhibited the growth of Fusarium fungus colony, in vitro. This inhibition was more pronounced, when Trichoderma fungus were cultured two days before Fusarium fungus, as they compared with simultaneous culture or when Trichoderma cultured after Fusarium fungus. The three isolates have similar sensitivity vis-a-vis the used pesticides, in terms of their impact on mycelium growth and spores germination, with some exception of little differences. So, regarding to mycelium growth, the results showed that: hexaconaxole difenoconazole ,carbendazim and chlorothalonil fungicides are more effective than others, as hexaconaxol and difenoconazole at 100 ppm completely inhibited mycelium growth of three isolates, while carbendazim and chlorothalonil inhibited the growth by 99.8 and 95.7% respectively, for local isolate (TI) 100.0 and 93.3% for local isolates (T5), 98.0 and 94.1 % for commercial isolate (T bio) , however, the Fostil Aluminum , Copper Hydroxide , and Metalaxil showed poor effects. kresoxim-methyl and pyrimethanil have a significant impact on mycelium growth in all isolates but in high concentrations of( 100 ppm). As, these two fungicides, inhibited the growth by 64.8 and 77.7%, respectively for the Ti isolate, 46.3 - 84.3% for the T5 isolate, and 68.0 - 95.9% For the T bio isolates. maneozeb at 100 ppm showed a poor impact on mycelium growth of T1 and T bio firngal isolates, so, it inhibited the growth of these isolates by 38.6 and 292% respectively, while it was very effective on T5 isolate and inhibited it by 93.2%. Regarding the fungicides impacts on spores germination, the results showed that: hexaconaxole , difenoconazole ,marcozeb and chlorothalonil, were more effective among the other ftungicides , so, hexaconaxoel difenoconazole and mancozeb at 100 ppm inhibited spores germination completely for the three isolates, while the chlorothalonil inhibited of spores germination completely at this concentration for the isolate TI Tbio. This concentration also inhibited spores germination by 95,6% for T5 isolate, as compared with control. While copper hydroxide, metalaxyl, fosetylaluminimn , carbendazim , pyrimethanyl and kresoxim-methyl showed poor effects. These laboratory results of fungicides impacts are in accordance with that results obtained from in vivo trials (tomato cultivation in plastic bags), where hexaconaxole pointed out an evident inhibition effect on the three Trichoderma isolates growth within 12 days, also it lost its influence after 30 days. Fosetylaluminium ,copper hydroxide had no impact on Trichoderma growth at different times, after the addition of the fungicides.