Distribution of Meloidogyne enterolobii in Eastern North Carolina and Comparison of Four Isolates

Abstract

The guava root-knot nematode (RKN), Meloidogyne enterolobii, is a particularly aggressive pathogen with limited known distribution in the United States. In 2011, M. enterolobii was identified on field crops in North Carolina for the first time. In collaboration with the North Carolina Department of Agriculture and Consumer Services Nematode Assay Laboratory, RKN-positive samples from the eastern half of North Carolina submitted to the laboratory were analyzed for Meloidogyne species identification using polymerase chain reaction (PCR) of individual nematodes. PCR primers specific for Meloidogyne incognita, M. javanica, M. arenaria, M. hapla, and M. enterolobii were used to analyze DNA from 203 RKN-positive samples representing a variety of field and vegetable crops grown in counties in the eastern half of North Carolina. M. incognita was the predominant species identified (32% of samples), and M. enterolobii was identified in 6% of samples including ones from sweetpotato, tobacco, and soybean crops. New detections of M. enterolobii were found in Nash, Greene, Sampson, and Harnett counties in addition to the previously identified locations in Johnston, Wayne, Columbus, and Wilson counties. Four isolates of M. enterolobii populations were collected from soybean and sweetpotato crops in Johnston, Greene, and Wilson counties and reared on ‘Rutgers’ tomato plants in the greenhouse. Potential differences in virulence among the four M. enterolobii populations were not detected in greenhouse infection assays on six selected resistant and susceptible sweetpotato genotypes in two independent tests.