Lindakumbura, U.L.W.Y.S.Ranasinghe, C.De Costa, D.M.2026-02-062026-02-062024-08-29Proceedings of the Peradeniya University International Research Sessions (iPURSE) – 2024, University of Peradeniya, P 2351391-4111https://ir.lib.pdn.ac.lk/handle/20.500.14444/7546Bacterial wilt caused by Ralstonia solanacearum, poses a significant threat to potato cultivation; hence reducing pathogenic soil bacterial density is a strategic management approach. This study evaluated the effect of five locally-available soil amendments on reducing the density of R. solanacearum in a potato-growing field subjected to the application of the amendments for three consecutive seasons. Half- burn paddy husk, rice husk biochar, and radish and mustard plant residues were used as soil amendments and each was applied at a rate of 2 kg/m² on fresh weight basis. A previously identified effective soil amendment comprised of fresh wild sunflower leaves (Tithonia diversifolia) at 2 kg/m², urea (20 g/m²) and CaO (200g/m² ) and soil without any amendment (untreated control) were used for comparison. Potato (var. Granola) was planted two weeks after the incorporation of soil amendments. The treatments were laid out as a randomized block design with three replicates. Soil samples were collected five times over the cultivation season (i.e., before incorporation of the amendments, at the time of planting, and one, two- and three-months post-planting). Samples were cultured on TZC medium by the dilution plate technique and the density (cfu/g of soil) of the virulent and avirulent R. Solanacearum was quantified based on colony morphology. Over the growth period, virulent R. solanacearum population density was significantly reduced (P<0.0001) by rice husk biochar, Thithonia + Urea + CaO and radish and mustard plant residue treatments compared to the soil not treated with any amendment, exhibiting no significant difference among the four treatments. Percentage avirulent R. Solanacearum count was significantly (P<0.0001) higher in soil treated with radish and mustard residues (i.e. 86.5% and 81.2%, respectively) and Thithonia + Urea + CaO (i.e. 73.3%) treatments. Results revealed the potential of reducing pathogenic soil R. solanacearum density by repeated application of above three treatments.en-USBacterial WiltHalf-Burn Paddy HuskMustard ResiduesRadish ResiduesRice Husk Bio CharArticle