Common Corn Nematode Characteristics

August 3, 2009

By Greg Tylka, Department of Plant Pathology

Awareness of and interest in corn nematodes seems to be growing along with the crops this season. Growers and agronomists are asking lots of good questions about how nematodes feed on corn, what soils they prefer, how much corn yield loss they cause, etc.  Answers to those questions can be confusing and frustrating because there are more than a dozen different types of corn nematodes and the different species vary in their biology and behavior. The table below lists the basic characteristics of different types of corn nematodes.

* The damage thresholds listed in the table above are expressed as numbers of nematodes per g of root for lance and lesion nematodes; all others are numbers of nematodes per 100 cc soil.

These damage thresholds were established in the 1970s and 1980s and have not been verified with modern corn hybrids. The thresholds should not be considered absolute values for modern corn production systems. Also, threshold values will vary among states and universities; the values presented are those used by Iowa State University.


Greg Tylka is a professor of plant pathology with extension and research responsibilities in management of plant-parasitic nematodes. Tylka can be contacted at or by calling (515) 294-3021.  

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Greg Tylka Professor

Dr. Greg Tylka is a professor in the Department of Plant Pathology and Microbiology at Iowa State University with extension and research responsibilities for management of plant-parasitic nematodes. The focus of Dr. Tylka's research program at Iowa State University is primarily the soybean cyst n...