Effect of Essential Oils of some Medicinal-Plants on Phytonematodes

The essential oils of four medicinal plants belonging to Lamiaceae were explored for phytonematode control. The four oils inhibited (P < 0.05) nematode motility but Mentha spicata was generally more effective in reducing the numbers of active nematodes followed by Thymus vulgaris, Majorana hortensis and Mentha longifolia. The main corresponding compound of each oil, determined by GLC analysis, was carvone (58.14%), P-cymene (40.5%), terpinen-4-ol (41.6%) and carvone (70.36%). Soil stages of the reniform nematode were more affected by the oil than those of the ring and lance nematodes. When transferred to water, the total nematodes that regained their activeness ranged from 12% for T. vulgaris to 60% for M. longifolia. The four 0.1 oil solutions inhibited more than 80% of Meloidogyne incognita-juvenile hatching compared to about 3.5% at the control. The content of oxygenated compounds in these oils ranged from 45.79% to 96.5% and may be partially responsible for the nematicidal effects.