TY - JOUR AU - Hlokwe, Mapula T.P. AU - Kena, Mapotso AU - Mamphiswana, David N. PY - 2020/11/26 Y2 - 2024/03/28 TI - Application of plant extracts and Trichoderma harzianum for the management of tomato seedling damping-off caused by Rhizoctonia solani JF - South African Journal of Science JA - S. Afr. J. Sci. VL - 116 IS - 11/12 SE - Research Article DO - 10.17159/sajs.2020/7860 UR - https://sajs.co.za/article/view/7860 SP - AB - <p>Seedling production under smallholder farming systems can be negatively affected by both abiotic and biotic factors. Seedling damping-off caused by <em>Rhizoctonia</em> solani is one of the major biotic factors which causes significant yield reduction. Management is mainly based on the application of synthetic fungicides and cultural practices. However, both methods have limitations which result in their inefficiency. Several studies have reported on the use of plant extracts and biological control to manage plant diseases. The aim of this study was to formulate an effective and practical approach to manage tomato seedling damping-off using extracts of <em>Monsonia burkeana</em> and <em>Moringa oleifera</em> and a biological control agent <em>Trichoderma harzianum</em>. The efficacy of both extracts was investigated under laboratory conditions to determine the most suppressive concentration to <em>R. solani</em> growth. Methanolic extracts from both plants significantly suppressed pathogen growth at different concentrations. <em>M. burkeana</em> significantly reduced <em>R. solani</em> growth at 8 g/mL (71%) relative to control whilst <em>Moringa oleifera</em> extract reduced pathogen growth by 60% at a concentration of 6 g/mL. The highest suppressive concentrations were further evaluated under greenhouse conditions to test their efficacy on seedling damping-off. In damping-off treatments, both plant extracts and <em>T. harzianum</em> also significantly reduced (p=0.5) pre- and post-emergence damping-off incidence. <em>M. burkeana</em> recorded the highest suppression at 78%, followed by <em>M. oleifera</em> at 64%. <em>Trichoderma harzianum</em> reduced incidence of damping-off by 60% and this was higher than both plant extract treatments.</p><p><strong>Significance:</strong></p><ul><li>The use of <em>M. burkeana</em> and <em>M. oleifera</em> extracts and <em>T. harzianum</em> effectively suppressed pathogen growth and disease incidence and can be used to reduce the use of synthetic pesticides that are harmful to the environment and human health.</li><li>Application of plant extracts and biological control agents as possible alternatives to synthetic fungicides is considered a sustainable and affordable practice for smallholder farmers.</li></ul> ER -