Nematicidal activity of essential oils and their components against the root-knot nematode

Nematicidal activity of essential oils extracted from 27 spices and aromati c plants were evaluated in vitro and in pot experiments. Twelve of the twen ty-seven essential oils immobilized more than 80% of juveniles of the root- knot nematode Meloidogyne javanica at a concentration of 1,000 mu l/liter. At this concentration, most of these oils also inhibited nematode hatching. Essential oils of Carum carvi, Foeniculum vulgare, Mentha rotundifolia, an d Mentha spicata showed the highest nematicidal activity among the in vitro tested oils. These oils and those from Origanum vulgare, O. syriacum, and Coridothymus capitatus mixed in sandy soil at concentrations of 100 and 200 mg/kg reduced the root galling of cucumber seedlings in pot experiments. T he main components of these essential oils were tested for their nematicida l activity. Carvacrol, t-anethole, thymol, and (+)-carvone immobilized the juveniles and inhibited hatching at >125 mu l/liter in vitro. Most of these components mixed in sandy soil at concentrations of 75 and 150 mg/kg reduc ed root galling of cucumber seedlings. In 3-liter pot experiments, nematici dal activity of the essential oils and their components was confirmed at 20 0 and 150 mg/kg, respectively. The results suggest that the essential oils and their main components may serve as nematicides.