The role of Cinnamomum zeylanicum essential oil, (E)‐cinnamaldehyde and (E)‐cinnamaldehyde oxime in the control of Meloidogyne incognita

The search for natural nematicides that are biodegradable with little or no human toxicity has intensified in recent years. In this context, the use of essential oils has the potential to function as an alternative plant–parasitic nematode control strategy, and their characterization may identify new nematicidal molecules. In this study, the nematicidal activity of Cinnamomum zeylanicum essential oil, its most abundant biochemical component and its analogue were evaluated against Meloidogyne incognita. Mean LC50 and LC95 values for C. zeylanicum oil were 49 µg/ml and 131 µg/ml, respectively. When J2 placed in C. zeylanicum oil at its LC50 concentration were used to inoculate tomato plants, the reduction in numbers of galls and eggs versus samples inoculated using J2 and no C. zeylanicum oil was 98%. C. zeylanicum essential oil reduced levels of M. incognita J2 that hatched 38%–54%, while carbofuran (positive control) did not prevent hatching. C. zeylanicum oil applied at a concentration of 800 µg/ml to a potted substrate containing infested tomato plants significantly reduced numbers of M. incognita galls. The cinnamaldehyde molecule within C. zeylanicum oil had LC50 and LC95 values of 64 and 768 µg/ml, respectively, while LC50 and LC95 values for cinnamaldehyde oxime were 323 and 529 µg/ml, respectively. Both cinnamaldehyde and its oxime inhibited hatching in M. incognita J2. These findings indicate that C. zeylanicum essential oil, its major biochemical component, cinnamaldehyde and cinnamaldehyde oxime (a cinnamaldehyde analogue) can be used to reduce levels of M. incognita.