Comparisons of nematode assay efficiencies and recommendations across 10 state nematode assay labs utilizing turfgrass

Nematode assay extraction methods vary among state laboratories for quantifying plant-parasitic nematodes (PPNs) from turfgrass samples, which can lead to differences in nematode population estimates and management recommendations for turfgrass. This study compared the extraction efficiencies of 10 state nematode assay labs in the eastern United States using homogenous turfgrass soil samples. Random samples were collected from three locations; homogenized; and distributed to each lab. Three labs used semi-automatic elutriation, while seven employed hand sieving with centrifugation and sugar floatation. Variability in population estimates among state labs was evident in five of six recorded PPN genera by state and four of six by hand-sieving. Hoplolaimus spp. were different when compared by semi-automatic elutriation with all other genera recorded being similar. Despite variations in counts, recommendations for nematode management were generally consistent within each lab. These findings highlight the importance of using the same assay lab over time for reliable nematode monitoring and suggest that automation may reduce the variability in nematode extraction.