Thus, soybeans would be the most effective of the alternate crops because there was no evidence that this crop is affected by the needle nematode. Control of grasses in the field, both in the current year and in the rotation crop, is important. Some of the highest nematode populations I have seen were from soybean fields with poor grass control. Although the nematodes could not feed on soybeans, they were building up on the grasses not controlled by the herbicide program. This allows corn nematode populations an extra year to build until the corn crop is planted the following year.
Soil testing is needed to identify correctly the nematodes present in corn fields.
Symptoms of crop injury from nematodes is not distinct and can resemble those from many other factors. Samples should be taken in the early spring or when cool weather occurs. Keep samples cool until they are sent.