Biological Control of Bipolaris spicifera, Curvularia lunata, Fusarium spp., Nigrospora oryzae, Exserohilum rostratum, Alternaria alternate and Thanatephorus cucumeris on Iraqi Rice under Laboratory and Greenhouse Conditions

This research dealt with findings that included laboratory and greenhouse studies on the efficacy of our isolates of Trichoderma spp. in controlling Fusarium spp., Nigrospora oryzae, Exserohilum rostratum, Bipolaris spicifera, Curvularia lunata, Alternaria spp., and Thanatephorus cucumeris. Ten isolates of Trichoderma spp. were pre-screened on chitin plates to determine its ability to digest chitin therefore indicating the presence of chitinase which is a good disease resistance candidate. In vitro test conducted with Trichoderma isolate T.7 against 23 isolates of pathogens via the dual culture technique showed that isolates exhibited high antagonistic activity and reduced radial growth for each pathogen. As a consequence of dual culture assay, greenhouse study was conducted to determine the effectiveness of Trichoderma isolate T.7 to suppress major phytopathogens by using local rice variety cv. Forat Anbar as the model plant in autoclaved soil. Four parameters were tested; antagonistic activity, disease incidence, disease severity and population density parameter of Trichoderma isolate T.7 for each pathogen. The greenhouse experiment exhibited Trichoderma isolate T.7 greater efficiency of reducing disease severity in majority of pathogens e.g. T.7+T.cucumeris R2, T.7+F.solani R11, T.7+N. oryzae R9 and T.7+A.alternata R20 which reduced disease severity by approximately 2.2 %. Trichoderma isolate T.7 addition had significant effect on growth parameters of rice plant, fresh and dry weight as well as nitrogen and protein concentration.