Tylenchorhynchus species Stunt Nematodes Damage to Corn.   Stunt nematodes are common associates of corn, but are generally considered mild pathogens, at best. Biology.   Tylenchorhynchus are didelphic, medium-sized nematodes.  Ecology.   Stunt nematodes favor sand loam or loam soil, and are found in the mid-western U.S. and India. Symptoms.   Some stunting of corn in greenhouse studies has been shown, but in most instances pathogenicity has not been demonstrated. Damage to other crops.  Control.