Nematicidal activity of essential oil from lavandin (Lavandula × Intermedia emeric ex Loisel.) as related to chemical profile

Essential oils (EOs) from lavandin are known for a large spectrum of biological propertiesbut poorly and contrastingly documented for their activity against phytoparasitic nematodes. Thisstudy investigated the toxicity of EOs from three different lavandin cultivars, Abrialis, Rinaldi Cerioni,and Sumiens, either to juveniles (J2) and eggs of the root-knot nematode Meloidogyne incognita and toinfective stages of the lesion nematode Pratylenchus vulnus. The suppressive activity of treatmentswith EOs from the three lavandin cultivars in soil infested by M. incognita was also investigatedin a greenhouse experiment on potted tomato. The compositional profiles of tested EOs werealso analyzed by GC-FID and GC-MS. Linalool was the major component of all the three EOs, asaccounting for about 66%, 48%, and 40% of total EO from cv Rinaldi Cerioni, Sumiens, and Abrialis,respectively. Linalool acetate was the second most abundant compound in the EOs from cv Abrialis(18.3%) and Sumiens (14.9%), while significant amounts of camphor (11.5%) and 1,8-cineole (12.1%)were detected in cv Rinaldi Cerioni and Sumiens EOs, respectively. The mortality of M. incognita J2peaked 82.0%, 95.8%, and 89.8% after a 24 h treatment with 100 mg·mL-1solutions of cv Abrialis,Rinaldi Cerioni, and Sumiens EOs, respectively. Infective specimens of P. vulnus were largely moresensitive than M. incognita J2, as there were peak mortality rates of 65.5%, 67.7%, and 75.7% after4 h of exposure to Abrialis, Rinaldi Cerioni, and Sumiens EO, respectively. All three lavandin EOssignificantly affected also M. incognita egg hatchability, which reduced to 43.6% after a 48 h egg massexposure to a 100 µg·mL-1solution of cv Rinaldi Cerioni EO. Soil treatments with the three lavandinEOs strongly reduced, according to a dose-effect relationship, density of M. incognita eggs, and J2both 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 tomatoplant growth.