Nematicidal <i>trans</i>-Anethole Blends Paralyzing <i>Meloidogyne incognita</i>

Nematodes have a negative impact on crop production and yield. The use of synthetic formulations to control plant parasitic nematodes carries both environmental and human health risks. As these agrochemicals are gradually being phased out, recent research has been focused on finding more environmentally friendly, plant-based alternatives. This study aims to investigate the effectiveness of botanicals, used alone or in artificial blends, in paralyzing <i>Meloidogyne incognita</i> second-stage juveniles (J2s) immersed in test solutions or exposed to vapors. We tested thymol, <i>trans</i>-anethole, and two lavender essential oils, referred to as LEOA and LEOB, which vary in their flower and stem compositions. We also employed in our study <i>Melia azedarach</i> aqueous extract (MWE), already proven to have considerable nematicidal activity. According to our findings, all treatments used individually exhibited considerable efficacy, even LEOA and LEOB first reported herein. In addition, all blends exhibited significant synergism, and the best-performing were <i>trans</i>-anethole/thymol, being synergic to paralyzing J2s for up to two days, and <i>trans</i>-anethole/LEOB as well as <i>trans</i>-anethole/MWE, provoking irreversible paralysis since the first day of J2 immersion in test solutions. Most importantly, the blend of <i>trans</i>-anethole with LEOA displayed the best effective synergism against <i>M. incognita</i> both for immersion and fumigation methods. Lastly, the chemical composition analysis displayed linalyl acetate and <i>β</i>-linalool as the major components of LEOA and <i>β</i>-linalool and eucalyptol as the major components of LEOB.