Toxicity of methanolic leaf extracts and essential oils from various plants to the root-knot nematode Meloidogyne incognita

Abstract

The methanolic leaf extracts and essential oils of eight plants viz., Callistemon lanceolatus, Cymbopogon winterianus, Eucalyptus sp., Lantana camara, Nerium oleander, Ocimum basilicltm, Ocimum sanctum and Vitex negundo were tested in vitro against second stage juveniles of Meloidogyne incognita at 0.5, 0.1 and 0.02 per cent concentrations. In plant extracts of o. sanctum, C. winterianus, Eucalyptus sp., o. basilicum, and V negundo, hundred per cent mortality was observed at 0.5 per cent concentration, whereas at 0.1 per cent concentration only o. sanctum gave similar results. Essential oils of o. sanctum resulted in 100 per cent mortality even up to 0.02 per cent concentration while o. basilicum also was very effective at the same concentrations. It is speculated that nematicidal activity in these plants may be due to compounds like terpinen-4-ol in methanolic extracts and linalool in essential oils, respectively.