I’ve received lots of inquiries in the past few weeks about sampling fields for nematodes that feed on corn. Most every Iowa field has one or more different nematode species present at low numbers. But it’s only when numbers are at damaging levels that yield loss will occur.
Unfortunately, there is no reliable relationship between the numbers of nematodes that feed on corn in soil samples collected in the fall and the damage that the nematodes may (or may not) have caused earlier in the growing season. Also, numbers of nematodes in fall samples do not correlate or predict the potential for damage in the next growing season.
Sampling to check for damaging levels of nematodes on corn needs to be done during the growing season – ideally when symptoms of damage are seen.
Navigate to an ICM News article on this topic for more information about how to take samples in-season to assess the situation with nematodes that can feed on corn.
Source: Iowa State Extension