ABSTRACT

A field trial was undertaken to study the efficacy of plant extracts in the management of rice stem borers at Michael Okpara University of Agriculture, Umudike, Southeastern Nigeria during 2016 and 2017 cropping seasons. The experiment was laid out as 3 x 4 split plot arranged in Randomized Complete Block Design (RCBD) with three replicates. The main plot contained varieties of rice: FARO 44, FARO 52, Ovuku and the sub plot treatments consisted of 5 % each of aqueous extracts of Jatropha curcas L., Ageratum conyzoides L., synthetic insecticide (Furadan 4 G) and the untreated control. Furadan 4 G was applied at 50 g per square metre. The treatments were applied at the tillering stage and booting stage. The results showed that Furadan 4 G and the plant extracts significantly (P<0.05) reduced the percentage dead hearts and whiteheads caused by stem borers compared to untreated control. The yield of the rice in the two years trials were significantly higher (P<0.05) in Furadan 4 G treated plants followed by J. curcas and A. conyzoides than the control. FARO 44 and FARO 52 varieties were less susceptible to the stem borers and had higher grain yield than Ovuku variety. The results suggest that aqueous extracts of J. curcas and A. conyzoides can be suitable alternative to synthetic insecticides for controlling rice stem borers without altering the agro-ecosystem. Incorporating 5 % aqueous extracts of J. curcas and A. conyzoides into lowland rice production in the area will help to mitigate stem borers attack and improve crop yield. FARO 44 and FARO 52 varieties which demonstrated less susceptibility to the stem borers and higher yield should be adopted by farmers to produce bulk of rice.