Effect of Sowing Dates, Intra-row Spacings and Pesticides on Maruca vitrata (Fab.) (Lepidoptera: Pyralidae) Damage on Cowpea in Samaru, Northern Guinea Savanna

Abstract

A field trial was conducted during the 2015 and 2016 cropping seasons in Samaru northern Guinea savanna agro-ecological zone, at the Teaching and Research Farm, Institute for Agricultural Research, Ahmadu Bello University (IAR/ABU) Zaria, Nigeria. The objective of the research was to test the effect of sowing dates, intra-row spacings and biopesticides in the control of cowpea pod-borer, Maruca vitrata (Fabricius). The experiment was laid out in split-split plot design with sowing dates allocated to the main plot, intra-row spacings to the sub-plot and pesticides allocated to the sub-sub-plot. The treatments were randomized and replicated three times. Data collected on numbers of flower and pod damage were subjected to the analysis of variance and significant means were separated using LSD at 5%. The result at 10 WAS showed that varying sowing dates significantly (P .01) reduced percentage flower damaged by M. vitrata. Lower damage was recorded in SD3 (5.56, 5.00 and 5.28) while SD2 recorded the highest damage (11.94, 12.22 and 12.08) during 2015 and 2016 cropping season and the combine. The result of interaction of SD3 and MaviMNPV gave the least flower damage (5.00). MaviMNPV treated plots reduced percentage flower damage (7.04, 6.30 and 6.67) at (P .05) but was not significantly better than NKE (9.82, 6.67 and 8.24) and Cyper diforce (7.41, 10.74 and 9.07) which were statistically at par but lower than the control (11.11, 16.68 and 13.89). The interaction of SD3 and Cyper diforce produce the least pod damage (6.67). Also delaying sowing date to SD3 was observed to significantly reduce percentage cowpea pod damage by M. vitrata at 10 WAS (15.28, 6.67 and 10.97) than the other SDs. Similarly, plots treated with Cyper diforce significantly (P .01) observed lowest pod damage (15.37, 9.26 and 12.32) than NKE and MaviMNPV. The control recorded significantly higher pod damage in both years (9.82, 5.19 and 7.50). Cyper diforce treated plots gave the highest yield of 394.56, 887.69 and 976.51 kg ha during 2015 and 2016 cropping seasons and combine but was statistically similar (P .01) with NKE and MaviMNPV. The interaction of SD2 and Cyper diforce gave the highest grain yield (1673.45 kg ha). The effect of sowing cowpea on 11th August (SD2) and Cyper diforce application will give a better control of M. vitrata for an increased yield of cowpea in the study area.