Reports of problems with corn nematodes are on the rise in various parts of the Corn Belt. Purdue University entomologists who work with nematodes say the weather so far this spring likely hasn't been kind to various nematodes in the Eastern Corn Belt, but that may not be the same everywhere. When scouting corn today, especially corn in the early vegetative stages, it's a pest that should be considered as a possible cause of problems until you can rule it out through troubleshooting.
Cool, wet springs are typically more favorable for nematodes on corn, notes Jamal Faghihi, Purdue University nematode specialist. That's not been the type of spring that's unfolded so far in parts of the Corn Belt. Nevertheless, if roots are affected and corn is stunted, nematodes could be at work. The number one symptom of nematode damage is stunted corn. When you dig up plants carefully, he notes, and compare a stunted plant to a normal plant, it will be obvious that the roots are not as developed on the stunted plant. That's because they've been damaged by nematode feeding- at least that's one possible cause.
One problem with nematodes is making a positive diagnosis, since the nematodes are so small. You can use the process of elimination, ruling out other causes. In the end, the best way to make sure you're dealing with nematode problems is to sample for them, Faghihi notes.
If you've had diagnosed nematode injury on corn before, you may want to dig up entire small stunted plants with soil on the roots and send them to a lab for analysis. Keep the soil and roots cool and moist. Purdue University has a nematology lab that can do the sampling. Frees are charged for nematode sampling.
We're approaching the best time to sample for corn nematodes, about 6 to 8 weeks after germination, the nematologist says. Another method is to pull a soil sample, mixing cores from various locations, pulling samples 6 to 8 inches deep next to plants that are performing poorly. Visit this site for more sampling instructions, and the sampling fee schedule if you're going to use the Purdue lab. If you live elsewhere, you may want to use a lab in your part of the Corn Belt.
Find information about the Purdue lab and more intricate details for testing at: www.entm.purude.edu/nemtology/samples.html.