EFFECT OF TIME OF APPLICATION OF SYNTHETIC PESTICIDES ON INSECT PEST DAMAGE TO, AND YIELD OF PIGEON PEA (Cajanus cajan (L.) Millsp.) IN MAKURDI, SOUTHERN GUINEA SAVANNA, NIGERIA

Field experiments were conducted in the Teaching and Research Farm of University of Agriculture, Makurdi, Nigeria, in 2011 and 2012 cropping seasons to evaluate the effect of synthetic pesticides on insect damage to, and yield of pigeon pea (Cajanus cajan (L.) Millsp.). Experimental design was randomized complete block with four replications of three weekly applications of cypermethrin + dimethoate (0.13kg+0.56kg a.i./ha) at mid-vegetative (MV), mid-flowering (MF), midpodding (MP), mid-vegetative and mid-flowering (MV +MF), mid-vegetative and mid-podding (MV + MP), mid-flowering and mid-podding (MF +MP) and mid-vegetative through to mid-podding (MV +MF +MP) stages of pigeon pea growth. An untreated plot served as the control (CT). Sprays applied at mid-flowering stage resulted in low damage by Maruca vitrata larvae and pod-sucking bugs, dominated by Clavigralla tomentosicollis, to pods (33.0-35.1% in 2011 and 34.1-38.0% in 2012), and seeds (31.8 - 34.6 % in 2011 and 33.4 - 36.0 % in 2012). Consequently, pod yield (153.0 - 175.0 pods/plant in 2011 and 111.0-147.5 in 2012), pod weight (0.8-1.1tha-1 in 2011and 0.7-0.8tha-1 in 2012), and seed yield (0.7 - 0.9t ha-1 in 2011 and 0.5 - 0.7t ha-1 in 2012) were significantly higher compared with plots sprayed at mid-vegetative and mid-podding stages. Three weekly insecticide sprays commencing at mid-flowering stage of pigeon pea production is recommended given the profit margins of N97,811.00 in 2011 and N37,811.00 obtained in 2012. Keywords: Pigeon pea, Insecticide application, Insect damage, Crop growth stages, Yield