NEMATICIDAL ACTIVITY OF ALSTONIA BOONEI AND BRIDELIA FERRUGINEA LEAVES

Chemical environmental hazards warrant researches on green chemistry. Screen house and field studies were conducted to investigate the natural nematicidal potential of Alstonia boonei and Bridelia ferruginea leaves. The leaves were extracted successively using n- hexane, ethyl acetate and ethanol; the crude extracts were tested on Meloidogyne incognita that infects Corchorus olitorius in a 9 x 4 x 3 factorial experiment. In the Screen house and field, Alstonia boonei ethanol extracts (ALSB/EtOH) caused a significant (p<0.05) increase in plant height and number of leaves which compared significantly with that of reference standard carbofuran, whereas Alstonia boonei ethyl acetate extract (ALSB/EtOAc) and Bridelia ferruginea ethyl acetate extract (BRDF/EtOAc) influenced the production of higher number of branches which was similar to that of carbofuran. Nematodes were significantly (p<0.05) absent in the soil and root of plants that received the highest concentrations (75% and 50%) of ALSB/EtOH, ALSB/EtOAc and Bridelia ferruginea ethanol extracts. Corchorus olitorius plants that received carbofuran and ALSB/EtOH flowered significantly earlier than plants treated with aqueous extracts of Alstonia boonei and Bridelia ferruginea, which also produced significantly (p<0.05) lower plant height, fewer leaves, fewer branches and had nematodes in their root and soil at harvest. Phytochemical screening of plant extracts revealed the presence of alkaloids, flavonoids, anthraquinones, tannins and saponins. The extracts of the leaves of A. boonei and B. ferruginea were nematicidal and appear to hold promise as natural, biodegradable and environmentally friendly alternative crop protectants against Meloidogyne incognita.