Rhizoctonia solani Control in Field Grown Cabbage (Brassica oleracea) Using Moringa oleifera Extracts, Beatrice, Zimbabwe
M. Goss *
School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa AND Faculty of Agriculture, University of Zimbabwe, P.O.Box MP167, Mt Pleasant, Harare, Zimbabwe.
P. Mafongoya
School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa.
A. Gubba
School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa.
*Author to whom correspondence should be addressed.
Abstract
Aims: To determine the antifungal activity of Moringa oleifera leaf, seed, and bark extracts in suppressing Rhizoctonia solani disease in field grown cabbage (Brassica oleracea).
Study Design: The experimental design was a 3 x 3 factorial laid out in a split plot in two blocks with three replications.
Place and Duration of Study: Field experiments were carried out in the November 2015 to April 2016 season at Victory Farm in Beatrice, Zimbabwe to evaluate the efficacy of Moringa oleifera leaf, bark and seed aqueous extracts in controlling bottom rot caused by Rhizoctonia solani in cabbages.
Methodology: Bottom rot and root rot diseases are mainly caused by soil-borne pathogens such as Rhizoctonia solani. The fungal pathogen was isolated from diseased samples, identified and cultured. Cabbage plants were inoculated with the pathogens 5 weeks after crop emergence. Three Moringa extract concentrations of 60%, 100%, and 140% were sprayed as foliar applications weekly from week 7 after crop emergence until the week 11 after crop emergence. The antifungal activity for each of the different Moringa extract efficacy was evaluated by recording number of totally defoliated plants once every week for the duration of the study.
Results: Moringa extracts were significant in reducing the growth of fungi in cabbages (P = 0.05). The leaf and seed extracts which were not significantly different form each other in their antifungal activity. They both revealed a high level of control of Rhizoctonia solani with indice means of 1.552 and 1.697 respectively. The bark extract with a mean of 2.075 differed significantly from the leaf and seed extract in its antifungal properties (P = 0.05) and had the highest disease mean.
Conclusion: Rhizoctonia solani fungi growth on cabbage can be effectively reduced by using either seed or leaf extract sprays. Moringa seed and leaf extracts contain antifungal properties which suppressed R. solani progression in field grown cabbage.
Keywords: Moringa plant extracts, antifungal, leaf defoliation rate