This study is designed to investigate the effectiveness of these three Trichoderma species in controlling damping off disease caused by Pythium aphanidermatum in sweet pepper seedlings and to evaluate the contribution of the three Trichoderma species on overall growth performance and emergence indices in sweet pepper seedlings. Sweet pepper seeds treated with 2.5 x 10 6 conidia/ ml of Trichoderma harzianum, Trichoderma atroviride and Trichoderma koningii were sown to determine the emergence percentage at 7 Days after planting (DAP), 9 DAP and 14 DAP. Emergence Index and Emergence Rate Index were computed for each Trichoderma treatment. Data on plant growth parameters such as stem height, number of roots, root length, number of leaves, fresh weight, dry weight, seedling vigour assessment, and disease incidence percentage were measured on 30 day old seedlings inoculated with 5 X 105 spores/ ml Pythium aphanidermatum at 15-day old sweet pepper seedlings. Seedlings of sweet pepper treated with both Trichoderma atroviride and Trichoderma harzianum had higher emergence percentage than the un-treated seedlings, which was not significantly lower in emergence percentage from Trichoderma koningii treated pepper seedlings. The presence of these Trichoderma species in P. aphanidermatum infected sweet pepper seedlings, reduced disease incidence significantly than when there was none. Higher seedling vigour assessments and improved growth rates were recorded on 30 day old seedlings when treated with Trichoderma species either with or without P. aphanidermatum were observed, especially in T. atroviride plus pathogen. Trichoderma species, when presence enhance the growth of the developing plant root system viz-a viz the plant growth and yield through better nutrient uptake, production of growth promoting compounds and solubilization of phosphates, micronutrients and mineral cations like iron, manganese and magnesium necessary for plant metabolism.
