Frequency of occurrence of Heterodera glycines types, Meloidogyne spp. and eight other nematode taxa associated with soybeans in Georgia

Abstract

Soybean fields in Georgia were surveyed for plant-parasitic nematodes (PPNs) during the 2021 growing season. The frequency and population density of ten PPN taxa were determined in 144 soil samples collected from soybean fields located within 31 Georgia counties. Between 1-6 PPN taxa were identified in 97% of the soil samples with >50% of samples harboring four or more taxa. Spiral nematode (Helicotylenchus spp.) was the most prevalent nematode (85%), followed by lesion (Pratylenchus spp., 71%), stubby root (Trichodoridae, 69%), ring (Criconematidae, 54%), root-knot (Meloidogyne spp., 49%), stunt (Tylenchorhynchus spp., 11%), reniform (Rotylenchulus spp., 8%), cyst (Heteroderidae, 8%), dagger (Xiphinema spp., 4%), and lance (Hopolaimus spp., 2%). Fourteen soil samples from nine Georgia counties were confirmed to have the soybean cyst nematode, Heterodera glycines (SCN), based on morphological identification, molecular identification, and evidence of reproduction on soybean. HG type tests determined the virulence of each SCN population on resistant soybean. All SCN populations tested were able to reproduce at a female index ≥10% on PI 88788. HG type 2.- was the most frequent (57%), followed by HG type 1.2.- (29%) and HG type 1.2.3.- (14%). Meloidogyne incognita was the most frequently identified species of root-knot nematode (80%), followed by M. arenaria (28%), and M. javanica (6%). Our survey results serve to 1) raise awareness of PPNs among Georgia soybean producers to inform future management decisions and 2) improve information available to soybean breeders as they move forward with their efforts to incorporate multi-nematode resistance into improved soybean cultivars.