Effect of varieties and mulch types on foliar insect pests of okra [Abelmoschus esculentus L. (Moench)] in a humid tropical environment

Abstract

The effect of varieties and mulch types were evaluated on some vegetative insect pests of okra (Abelmoschus esculentus) at the Federal University of Technology, Owerri, Nigeria. A 3 x 5 factorial in randomized complete block design (RCBD) was used to lay out the trial. Three varieties of okra (NHAe47-4, V₃₅ and Lady’s finger) and five mulch types [dry palm fronds, dry grass, black polyethylene, groundnut (live mulch) and unmulch (as control)] were used as treatments. Ten tonnes per hectare (10 t ha^-1) of dry grass and dry palm fronds, respectively, were applied before planting. The black polyethylene mulch was applied to fit the 1 m x 3 m plot size. Groundnut seeds were planted between the okra plants, at a spacing of 60 cm x 25 cm, as live mulch. A 60 cm x 45 cm spacing was used to sow the okra seeds. Data collected were plant height, number of leaves, leaf area and number of damaged leaves. At different developmental phases of the crop, insect pests were sampled. Results indicated mulch application had significant effect on insect pest leaf damage whereas no significant differences existed between the varieties used. Black polyethylene mulch treated plants had the least insect pests attack and consequently, the lowest number of damaged leaves. The flea beetle Podagrica spp., cotton leaf roller Notarcha derogata, cotton strainer Dysdercus spp., whitefly Bemisia tabaci and Nigerian grasshopper Oedaleus nigeriensis were identified as the major vegetative insect pests of okra. It may be concluded that okra cultivated with plastic mulch reduced insect pests and produced healthier plants.

Keywords: Black Polyethylene, Dry Grass, Dry Palm Fronds, Insect Pests, Live Mulch, Okra Varieties