Determination of appropriate decomposition period of two organic materials for effective control of root-knot nematodes on okra

Abstract

The efficacy of fruit peelings and cow dung used as soil amendments each at the rates of 0, 4, 8, and 16t ha-1 in the control of root-knot nematodes on' okra was tested in two field trials at the National Horticultural Research Institute, Ibadan. The organic wastes were each ploughed 0,20m into the soil and were subjected to three decomposition periods of two, four and six weeks before okra seeds were sown. The plots that were not amended served as the control treatment. The layout was a 2 x 4 x 3 factorial experiment in a randomized complete block design with four replications. The results showed a consistent decline in nematode population and increase in yield of okra with increasing rate of each soil amendment. Regardless of each type of organic waste, six week­ decomposed wastes reduced nematode populations and improved yield more than two­-week decomposed manure. While the plants in fruit peelings amended soil recorded a higher level of nematode population reduction by 68.1% and resulted in a yield increase of 89.2% over the control, cow dung reduced nematode population by 64.6% with resultant yield increase of 30.9%. While the effect of year of study (Y) was not significant for the assessed parameters, the interaction between manure rate (M) at 16t ha-1 and decomposition period of six weeks recorded the best significant suppressive effect on nematode population and enhanced the yield of okra. The overall results thus suggest that the efficacy of fruit peelings was significantly better in nematode control, enhanced plant growth and yield response over the corresponding effect of cow dung on the measured parameters. Keywords: decomposition period, cow dung, fruit peelings, root-knot nematodes Moor Journal of Agricultural Research Vol. 5(1) 2004: 19-25