Soybean Root-Knot Nematode: A Diagnostic Guide

Pathogen: RKN are plant-parasitic, nonsegmented, soilborne roundworms causing root galls that belong to the genus Meloidogyne. The organisms that would come to compose this genus were first described in 1878 as pyriform (pear-shaped) worms parasitizing the roots of coffee trees in Brazil (Jobert 1878), but the name Meloidogyne was not used until 9 years later (de G€oldi 1887). Meloidogyne species were previously synonymized with the genus Heterodera but were later separated by Chitwood (1949). There are over approximately 100 species of RKN found worldwide (Hunt and Handoo 2009; Jones et al. 2013), but only a small number of species are considered economically important in soybean. These include Meloidogyne incognita (Kofold & White, 1919) Chitwood, 1949; M. arenaria (Neal, 1889) Chitwood, 1949 (syn. Anguillula arenaria, Heterodera arenaria, M. arenaria thamesi, M. thamesi, Tylenchus arenarius); M. hapla Chitwood, 1949; M. javanica (Treub, 1885) Chitwood, 1949 (syn. Anguillula javanica, Heterodera javanica, M. javanica bauruensis, Tylenchus [Heterodera] javanica) (Taylor and Sasser 1978); and M. enterolobii Yang and Eisenback, 1983 (syn. M. mayaguensis) (Ye et al. 2013). Other geographically limited Meloidogyne species may also affect soybean (Bellé et al. 2016; Hunt and Handoo 2009; Long et al. 2017). © 2021. The American Phytopathological Society.