Effects of <i>Moringa oleifera</i> Leaf Extract on Morphological and Physiological Growth of Cassava and the Efficacy in Control of <i>Zonocerus variegates </i>

Abstract

This work was carried out to study the effect of Moringa oleifera leaf extract (MLE) on the morphological and physiological growth characteristics of cassava (Manihot utilissima Pohl.); and its efficacy as organic insecticide in controlling Zonocerus variegatus infestation on the plant. The leaf extract was diluted in water at the ratios of 1:10, 1:20, 1:30 and 1:40. “Uppercut (R)” (30g dimethoate + 250g cypermethrin), used as water emulsifiable concentrate, was applied at the rate of 0.2 a.i./ha for comparison. Cassava hybrid, CR1247 was planted at the spacing of 1m x 1m. Moringa oleifera leaf extract was applied weekly while the dimethoate + cypermethrin was applied at three-weekly interval for two months. The experiment was laid out in a randomized complete block design (RCBD) with four replications. The Moringa oleifera leaf extract (MLE) dilution at the ratio of 1:30 MLE in water gave the highest percentage stem height difference (% SHD) at the eighth week after treatment with a value of 20.5% followed by 1:20, 1:10 MLE in water, dimethoate + cypermethrin and 1:40 MLE in water (i.e. 17.82%, 10.56%, 8.98% and 8.05% respectively). The control had the least % SHD. Dimethoate + cypermethrin had the highest percentage leaf number difference (% LND) at the eighth week after treatment with a value of 70.99% followed by 1:10, 1:30, 1:20 and 1:40 MLE in water in that order (i.e. 25.23%, 18.43%, 3.83% and 0.33% respectively). Control also had the least % LND. The 1:40 MLE in water treatment recorded the highest percentage leaf appearance (31%) at eight weeks followed by 1:30, 1:20, 1:10 and dimethoate + cypermethrin in that order (i.e. 29%, 28%, 26% and 20% respectively). Dimethoate + cypermethrin eradicated the insects and caused significant (P< 0.05) increase in the number of leaves and reduction in the percentage leaf abscission especially from the sixth week after treatment.

Keywords – Moringa, dimethoate + cypermethrin, insecticide, cassava hybrid.