Currently, there is considerable interest and continued discussion among growers, agronomists and university researchers about plant-parasitic nematodes that feed on corn. To find out if these microscopic worms are damaging a corn crop, soil and roots must be collected and sent to a qualified laboratory to determine which specific nematodes are present and at what population densities (numbers).
Iowa State University
Tylka, Gregory L., "Nematodes Damaging Corn This Year?" (2010). Integrated Crop Management News. 396.