Myrtus communis leaf extracts repel Meloidogyne spp. second‐stage juveniles and prevent root infection

Abstract

The use of repellents for nematode control has not been established. Leaf extracts of Myrtus communis, an evergreen shrub with wide distribution in the Mediterranean and some other regions, were tested for repellence of second‐stage juveniles (J2s) of Meloidogyne species. Extracts obtained with several solvents and water repelled M. javanica J2s on agar plates, with the 60% methanol extract showing the highest repellent activity. M. hapla J2s were also repelled by the aqueous and 60% methanol extracts. Adding the 60% methanol extract to fluopyram, a chemical J2 attractant, reduced and abolished, respectively, the attraction of M. javanica and M. hapla J2s to it. When the methanolic extract was added near lettuce seedling roots on an agar plate, the number of M. javanica, M. incognita and M. hapla J2s attracted to the root tips was reduced by 70.0%–98.2%, infection rates decreased by 50.1%–95.8% and root length increased by 61.8%–186.7% compared to control seedlings grown on the same plates. When the methanol extract was mixed into the agar plate, the three Meloidogyne species' attraction to and infection of lettuce seedlings was reduced by up to 75.4% and 100%, respectively, and root length increased up to 3.4‐fold. The acetone extract mixed into the agar reduced the attraction of M. javanica J2s to fluopyram but did not affect their repellence by KNO3. The results suggest that M. communis leaf extracts have repellent and infection‐inhibitory activity against Meloidogyne J2, offering potential control means for Meloidogyne species.