Occurrence of the Root-Knot Nematode Meloidogyne haplanaria in Vegetable Fields of South Georgia, U.S.A.

Abstract

Meloidogyne spp. were found at 4 and 14 second-stage juveniles per 100 cm3 of soil from two adjacent watermelon and cowpea fields, respectively, from randomly sampled vegetable fields in South Georgia. PCR products from two primer sets were obtained from single egg mass cultures for DNA sequencing of cytochrome c oxidase subunit II, tRNAHis, and large subunit 16SrDNA gene fragments. On the basis of molecular analyses, morphological measurements, and perineal pattern characteristics, the root-knot nematode in these fields was identified as M. haplanaria. Results from a pathogenicity study showed that M. haplanaria did not reproduce on cowpea and watermelon, with a reproduction factor not greater than 1, but successfully reproduced on nematode-susceptible and -resistant tomato cultivars and eggplant. The low population density of the nematode in the field of origin and nonhost status of watermelon and cowpea indicate that reproduction of the nematode must have occurred on a previous crop rotated in these fields. To the best of our knowledge, this is the first report of M. haplanaria in Georgia.