Evaluation of three species of trichoderma as potential bio-control agent against colletotrichum gloeosrioides ., a casual agent of anthracnose disease in onion

摘要

The research was conducted to screen and evaluate the effect of three Trichoderma species as a potential bio-control agent againstColletotrichum gloeosrioides isolated from onion under in vitro condition. In in vitro test, antagonistic effect of the three Trichodermaspecies against C. gloeorioides was evaluated using dual culture test and the presence of active compounds of the three antagonists wasdetermine while mycoparasitism interaction was also observed under microscope using slide culture technique. Pathogenicity testing wasalso determined using onion bulb as test crop. Results showed in the percent growth inhibition of the three Trichoderma species during 14days of incubation, T. longibrachiatum obtained the highest percentage inhibition of 64.68% compared to T. harzianum and T. asperellumwith 59.16% and 47.73% inhibition respectively. It was also observed that hypal coiling was common on the three Trichoderma speciesagainst C. gloeosrioides. The presence of active compounds among the three Trichoderma were also tested and it showed at 500 μl/ml crudeextract of T. longibrachiatum obtained the highest inhibition of 15.58% which make it more active against a wide range of microorganism.Pathogenicity test of C. gloeosrioides against the three Trichoderma showed the onion bulbs inoculated with the pathogen only was highlypathogenic. However, bulbs treated with the antagonist showed that C. gloeosporioides was observed as weak and mild pathogenic. Thiscould be concluded that the presence of Trichoderma species could lessen the pathogenic effect of C. gloeosporioides and could be used asnatural biocontrol agent of some plant diseases.