Application of Fatty Acid Esters on Meloidogyne incognita Infected Jew's Mallow Plants

Abstract

| Jew's mallow (Corchorus olitorius) is a vegetable of importance in Nigeria which is often times infested with root-knot nematodes (RKNs), thus reducing yield and expected income. Principally, synthetic nematicides are employed in the management of RKNs on agricultural fields. The synthetics are confronted with a web of regulations on account of their unhealty negative effect on humans and the environment. Plant protection is primarily saddled with replacing the synthetics. A promising technique is the application of bio-pesticides. Organic fatty acid esters (FAE) are reassuring materials with nematicidal activities. Medicinal plants are rich source of acid esters, hence Alstonia boonei (Apocynaceae) leaves were extracted cold in ethyl acetate. This yielded crude extract that was subjected to column chromatography (silica gel 100-120 mesh grade), which afforded fractions that were analysed with GCMS and FTIR for constituent identification. The result shows octanoic acid; hexanoic acid methyl ester; ethyl octanoate; 9, 12-octadecadienoic acid methyl ester; dodecanoic acid; octadecanoic acid methyl ester; decanoic acid; octadecanoic acid ethyl ester and tetradecanoic acid as the major components while the infra red spectral diagnostic signals agree with the expected vibrational frequencies corresponding to C-H and carbonyl C=O functional groups of fatty acid and esters. Jew's mallow plants infected with Meloidogyne incognita on the field were treated with the fatty acid esters (FAE) and compared to deionised water and carbofuran as control in two season trials. There was increase in biomass and vegetative growth with notable reduction in M. incognita reproduction in plants treated with FAE at 0.75 mg/ml in the first and repeat experiments. Juvenile population per gram root and soil were reduced significantly at 0.75 and 0.50 mg/ml of FAE in comparison with control. Late flowering was recorded in the untreated control experiment, while plants treated with FAE flowered notably earlier. Application of FAE is recommended for the sustainable management of M. incognita in Jew's mallow plants.