Studies on Soil Amendment Strategies and Neem Products for the Management of Insect Pests of Okra (Abelmoschus esculentus (L.) Moench)

Abstract

The effect of different soil amendment strategies, and neem products for the management of insect pests of okra was studied in the field at the Ashaiman irrigation project site. The insect pests encountered fell into seven orders belonging to twenty-three families. The important ones among these were Aphis gossypii (Glov.), Bemesia tabaci (Genn.), Dysdercus spp. Podagrica uniformis (Jac.), Heliothis armigera (Hb.) synonym Helicoverpa armigera (Hb,), Sylepta derogata (Fab.), Anthonomus grandis (Boh.) and Empoasca spp. Calidea spp. Pachnoda spp and Riptortus were also found attacking okra fruits in Ashaiman. The beneficial insects included Coccinella spp., Odonata spp. Cheilomenes vicinia (Muls.) and Rhinocoris rapax (L.). The neem products were less harmful to the beneficial insects and controlled homopteran pests better than the synthetic insecticide, dimethoate. Dimethoate was less effective in managing A. gossypii. and B. tabaci probably due to the development of resistance in these insects. In the field, the compost treatments improved plant vigour and enhanced their tolerance to pest attack than the sole chemical fertilizer, and gave significantly higher response in all yield indices studied. The sole fertilizer treated plants, however, performed better than the untreated control in fruit yield, damage, and vegetative yield indices studied. The combined effects of compost and aqueous neem seed extract (ANSE) at 50 g/1 enhanced okra resistance to insect pests attack, and improved yield and marginal benefit of over 100% the cost of production. ANSE was better than the formulated neem product, Neemazal at (2 ml/1), in managing the insect pests of okra, and compared favourably well with the synthetic insecticide, dimethoate 40% EC (75 ml/151). As a production package for okra, plants should be treated with compost prepared from cocoa husk, rice straw and poultry manure at (500 g/plant), ANSE (50 g/1) sprayed with cone nozzle is recommended.