The efficacy of selected local pesticides in prevention of leaf damage and improvement of yield in Brassica rapa subsp. pekinensis L. (Chinese cabbage)

Abstract

Vegetable constitutes a healthy diet which is rich in vitamins, minerals and fibre. However, production of vegetable is currently hindered  by several factors including pest infestation/pathogen infection. Pests and pathogens affect vegetable by interfering with growth and  yield. The impacts may be manifested in holes on leaves or reduced numbers of leaves that subsequently affect the yield. To overcome  problems associated with pests and/or pathogens synthetic pesticides are widely used. However, synthetic pesticides are blamed to be  costful and environmentally unfriendly. As a result vegetable growers in many countries have decided to rely on local pesticides in  attempt to improve growth and yield of crops. This study aims to evaluate the efficacy of a mixture of wood ash and soil, cow urine,  pawpaw seeds, chilli fruits and neem leaves for growing Chinese cabbage which is widely consumed in Tanzania. Standard methods were  used to prepare extracts of the aforementioned local materials and later on sprayed on growing Chinese cabbage. Normal water was  used for control plots. The results of One Way ANOVA revealed significant difference in leaf damage and yield of Chinese cabbage (p <  0.05). The order of increasing effectiveness of the local materials in protecting leaves of Chinese cabbage was: mixture of wood ash and soil > cow urine > pawpaw seeds > chilli fruits > neem leaves > control. A similar trend was obtained for improvement of yield of Chinese  cabbage. Intactness of leaves and improved yield of Chinese cabbage can be attained by spraying a mixture of wood ash and soil, and  cow urine. Further studies are recommended on the efficacy of the studied local materials in other horticultural crops. Also isolation of  active compounds in mixture of wood ash and soil, and cow urine for development of cheap and environmentally friendly pesticide is  recommended.