Nematicidal Activity of Essential Oil from Lavandin ( × Emeric ex Loisel.) as Related to Chemical Profile.

Essential oils (EOs) from lavandin are known for a large spectrum of biological properties but poorly and contrastingly documented for their activity against phytoparasitic nematodes. This study investigated the toxicity of EOs from three different lavandin cultivars, Abrialis, Rinaldi Cerioni, and Sumiens, either to juveniles () and eggs of the root-knot nematode and to infective stages of the lesion nematode . The suppressive activity of treatments with EOs from the three lavandin cultivars in soil infested by was also investigated in a greenhouse experiment on potted tomato. The compositional profiles of tested EOs were also analyzed by GC-FID and GC-MS. Linalool was the major component of all the three EOs, as accounting for about 66%, 48%, and 40% of total EO from Rinaldi Cerioni, Sumiens, and Abrialis, respectively. Linalool acetate was the second most abundant compound in the EOs from Abrialis (18.3%) and Sumiens (14.9%), while significant amounts of camphor (11.5%) and 1,8-cineole (12.1%) were detected in Rinaldi Cerioni and Sumiens EOs, respectively. The mortality of peaked 82.0%, 95.8%, and 89.8% after a 24 h treatment with 100 mg·mL solutions of Abrialis, Rinaldi Cerioni, and Sumiens EOs, respectively. Infective specimens of were largely more sensitive than , as there were peak mortality rates of 65.5%, 67.7%, and 75.7% after 4 h of exposure to Abrialis, Rinaldi Cerioni, and Sumiens EO, respectively. All three lavandin EOs significantly affected also egg hatchability, which reduced to 43.6% after a 48 h egg mass exposure to a 100 µg·mL solution of Rinaldi Cerioni EO. Soil treatments with the three lavandin EOs strongly reduced, according to a dose-effect relationship, density of eggs, and both on tomato roots and in soil, as well as significantly reduced gall formation on tomato roots. Finally, almost all soil treatments with the lavandin EOs also resulted in a positive impact on tomato plant growth.