Association of root-knot nematode (Meloidogyne javanica) in olive plantations in Rajasthan (India) and its natural suppression by Pasteuria penetrans

Abstract

This study aims to identify the root-knot nematode (RKN) at seven olive plantations in Rajasthan (India), and understand the possible spread of RKN and its bacterial parasite, Pasteuria penetrans through olive planting material (OPM). We identified the RKN as Meloidogyne javanica based on perineal pattern morphology and species-specific SCAR marker. RKN was prevalent at all the locations with high natural incidence (50–90%) of P. penetrans in the females dissected from unstained roots. An artificial exposure of air-dried soil of seven locations to healthy juvenile (J2) of M. javanica showed that the trend was consistent with the natural population. We conclude that root hardening media comprising of dried river sand and nematode-infested soil mixed at the secondary site (Jaipur) in India possibly resulted in M. javanica infection of OPM along with P. penetrans. Our study suggests that P. penetrans proliferated to suppressive levels and kept the nematode population below damaging levels.