(E)-cinnamaldehyde from the essential oil of Cinnamomum cassia controls Meloidogyne incognita in soybean plants

Abstract

Among the main problems faced by soybean producers is the nematode Meloidogyne incognita. Because nematicides that are more efficient and less toxic to humans and the environment than those available are desirable to control this pathogen, this work aimed at studying the essential oil of Cinnamomum cassia, which has been described as active in vitro against the nematode Bursaphelenchus xylophilus. At the concentration of 62 µg mL−1, it performed better than the nematicide carbofuran at 173 µg mL−1 in an in vitro assay with M. incognita eggs and second-stage juveniles. The main components of this oil were identified by gas chromatography–mass spectrometry analysis and submitted to in vitro assays with the nematode, which showed (E)-cinnamaldehyde (83.3% of the oil) as responsible for the nematicidal activity. Emulsions of the oil (500 µg mL−1) and this aldehyde (416 µg mL−1) reduced the numbers of M. incognita galls and eggs in soybean plants to values statistically equal to those obtained with carbofuran (415 µg mL−1). Vapors of the essential oil and (E)-cinnamaldehyde were also as active as the fumigant nematicide Basamid against M. incognita according to an in vitro assay. Cultivation of soybean plants in substrate inoculated with M. incognita eggs and treated with Basamid at 0.25 g (L of substrate)−1 or (E)-cinnamaldehyde at 1.0 mL (L of substrate)−1 caused a reduction in the nematode population to values statistically equal to each other. These results make (E)-cinnamaldehyde very promising for the development of new products to control M. incognita in soybean fields.