LAUSR

An emerging threat to agriculture, Meloidogyne enterolobii Yang & Eisenback, 1983 is a tropical species and considered to be the most damaging root-knot nematode (RKN) in the world because of its wide host range, aggressiveness, and ability to overcome resistance to RKN in many crops. It was first detected in the USA on ornamental plants in Florida in 2001, but has since been identified in North Carolina, South Carolina and Louisiana. Several thousand RKN populations were collected from North Carolina field crops, ornamental plants and turfgrasses for species identification in the Nematode Assay Laboratory in the North Carolina Department of Agriculture & Consumer Services (NCDA&CS). From 2006 to 2019, root systems showing galling symptoms were dissected under the microscope and females were obtained for DNA analysis. When only soil samples were submitted, the second-stage juveniles or males were used instead. Molecular characterization was performed by PCR using species-specific primers and DNA sequencing on the ribosomal DNA 18S-ITS1-5.8S and 28S D2/D3, and mitochondrial DNA CoxII-16S. One hundred and thirty-five representative RKN populations from North Carolina were characterized and identified as M. enterolobii. Six populations from China where the species was originally described were included in this study for identity confirmation and comparison. As of December 2019, M. enterolobii was confirmed from a limited number of fields in 11 North Carolina counties, including Columbus, Craven, Greene, Harnett, Johnston, Lenoir, Nash, Pitt, Sampson, Wayne and Wilson. Currently, M. enterolobii is the most important emerging RKN species in the USA and causes severe damage to agronomic and horticultural crops, especially sweetpotato in North Carolina.