The 2009-2010 Corn Nematode Survey in Illinois: Results and Implications
Department of Crop Sciences
University of Illinois, Urbana 61801
Judging from the number of questions we get about corn nematodes, this is a subject of intense interest to corn growers in Illinois. Several companies have developed and labeled products for nematode management, and several others are in various stages of product development and labeling. We are testing a number of these products in field and greenhouse trials during 2010, but the results will not be available until fall.
The purpose of the corn nematode survey was to help us understand the potential for corn yield loss due to nematodes by collecting baseline information on the distribution and population densities of corn-parasitic nematode species throughout the state. Last year at Agronomy Day, we reported on the results of a pilot project in 19 northern Illinois counties (north of I-80) conducted during 2008. We now have data from 78 counties sampled in 2009, and will have data from an additional 19 counties being sampled in 2010.
The most important finding from the survey is illustrated in the map (Fig. 1), which shows the distribution and population densities of the most common corn-parasitic nematode in Illinois: the lesion nematode. Each dot represents a single composite soil and root sample taken during early vegetative development, and the color of the dot represents the number of lesion nematodes counted per 100 cc soil. In addition, the dot color represents the risk of injury or yield loss. Over two-thirds of the samples contained populations of lesion nematode that were above the threshold for moderate risk of damage.
At least 6 different species of lesion nematode were identified. Two of these are well-known corn-pathogenic nematodes capable of causing significant yield loss. Others are known to parasitize corn, but their potential for injury resulting in yield loss has not been studied well. In general, central and northern Illinois are at higher risk for losses due to lesion nematode than is southern Illinois.
Many other corn-parasitic nematode genera were identified in the 2009 survey, although none were as common or potentially damaging as the lesion nematodes. We plan to complete the survey in June, 2010, and have all the data available by the end of the summer.