Effect of essential oils on the root-knot nematode management

In an attempt to find alternative compounds for the management of root-knot nematodes, whether essential oils would be absorbed by plants and affect the development of Meloidogyne javanica inside tomato roots was evaluated. First, the viability, in vitro, of the essential oils of Artemisia absinthium (wormwood), Mentha × piperita (peppermint), Origanum vulgare (oregano) and Thymus vulgaris (thyme) was assessed. Then, the same essential oils were tested in pot experiments, at concentrations of 0.25% (v / v) and 0.5% (v / v). In in vitro tests, all essential oils were effective in killing the juveniles, resulting in mortality rates of 99.0% at both concentrations. The essential oils of Mentha × piperita, O. vulgare and T. vulgaris were effective in reducing nematode hatching to about 2.0%. In tests conducted under greenhouse conditions, however, tomato plants treated with the essential oils of A. absinthium, Mentha × piperita and O. vulgare hadincreased the number of M. javanica eggs and galls. Therefore, despite being highly toxic to nematodes in vitro, some of the essential oils tested in this study increased nematode development.