Corn Nematodes and Soybean Cyst Nematodes

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Nematodes feeding on corn and soybean roots cells reduce the ability of the plant to take up water and nutrients. Yield losses, caused by nematodes, can easily go undetected, and may be attributed to herbicide carryover, sandy soils, soil compaction, and other problems. Nematode sampling, identification, and treatment may protect yield potential. Farmers may want to sample low performing areas of fields to determine whether or not nematodes are limiting yield potential.

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Figure 1. Corn root mass damaged by nematode feeding. Photo courtesy of J. Bond, Southern Illinois University.   
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Symptoms. Nematode feeding symptoms are most noticeable when environmental conditions cause plant stress. Common aboveground symptoms include wilting, yellowing, and stunting of growth. However, nematodes may cause yield loss without exhibiting aboveground symptoms. Common below-ground symptoms include swollen roots, lack of fine roots, minimal root branching, and necrotic lesions (Figure 1).Below-ground symptoms can differ depending on which nematode species is causing injury. For instance, different corn root symptoms may result from feeding by lesion, sting, or stubby-root nematodes. In many cases, nematode feeding occurs at the growth point of the root, and the resulting damage is apparent as stunted roots. Severe nematode damage will result in “stubby roots�? with many short, swollen roots.​

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Nematode damage is rarely uniform within a field, and damage is typically more visible in areas with sandier soils. A common misconception is that nematodes are worse in sandy soils. Nematodes infest many types of soil.Drought-prone, sandy soils may allow aboveground nematode damage symptoms to become more visible.

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Testing for Nematodes. To confirm the presence of nematodes in corn, soil and root samples must be taken and submitted to a nematode testing facility. Generally, only soil samples are required to confirm the presence of soybean cyst nematode (SCN). Treatment recommendations can be made after test results confirm nematode species that are present and their approximate population density. Refer to university recommendations for treatment thresholds. Nematode distribution can be very irregular within a field; therefore, it is important to collect several composite samples to provide an accurate population estimate.

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When collecting and shipping samples, handle with care to avoid killing nematodes before they reach the lab. Follow lab instructions for collecting, handling, and shipping all nematode samples.

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Management. Because there are many nematode species, identification is essential for determining the appropriate control option (Table 1). Management practices that reduce crop stress may help the crop overcome nematode feeding.

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CornLesion, Needle, Lance, Dagger, Root-knot, Sting, Stubby-root, Spiral, Stunt, Pin, Sheath, Ring, Stem13;10;
Soybean Soybean cyst, Columbia lance, Root-knot, Sting, Lesion, Reniform
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Table 1. Important Nematode Species in Corn and Soybean.

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The following agronomic practices may help growers manage potential nematode infestations.

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  • Fertilize according to soil test recommendations. Healthy plants are less susceptible to nematode damage.
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  • Maintain good weed control, even after harvest. Weeds can be hosts for nematodes and may serve as a food source for the following crop.
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  • Corn roots protected from corn rootworm are more vigorous and healthy, and may be less prone to nematode damage. Use the most advanced traits for root protection.
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  • For certain nematode species, rotating to a non-host crop can reduce populations.13;10;SCN resistant soybean seed products may help suppress SCN populations.
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  • Consider using a seed treatment product that protects corn and soybean seedlings and roots against nematodes. Acceleron® Seed Applied Solutions ELITE offering contains Poncho®/VOTiVO® which is a bacteria that lives and grows with young roots, creating a living barrier that nematodes cannot break through.
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  • An additional nematicide may be necessary to control high nematode populations. Check university recommendations for specific products.
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