A Survey of Plant-Parasitic Nematodes in Illinois Corn Fields, 2018 and 2020

One hundred forty-seven soil samples were collected from corn fields located within 63 Illinois counties during the 2018 and 2020 corn growing seasons. The soil samples were analyzed for frequency and population density of plant-parasitic nematodes. A total of 10 plant-parasitic nematode taxa were identified. Spiral nematode (Helicotylenchus spp.) was the most frequently observed nematode (frequency: 98.6%), followed by lesion nematode (Pratylenchus spp., 85.7%). Other taxa identified included cyst (Heteroderidae, 66.7%), stunt (Tylenchorhynchus spp., 33.3%), lance (Hoplolaimus spp., 29.9%), dagger (Xiphinema spp., 12.9%), pin (Paratylenchus spp., 12.2%), needle (Longidorus spp., 1.4%), stubby-root (Trichodoridae, 1.4%), and ring nematodes (Criconematidae, 0.7%). Nematodes with the greatest population densities included spiral (89 nematodes per 100 cm3 of soil), pin (36), and cyst nematodes (26). Among the 10 nematode taxa, 4.1, 7.1, and 2.3% of spiral, lesion, and lance nematode-positive samples exceeded estimated damage thresholds for corn for Illinois, respectively.