Now that harvest is complete, it is a perfect time to check your soil in preparation for next year’s crop.

With a collaboration between the Nebraska Soybean Board (NSB) and Nebraska Extension, farmers can receive free testing for soybean cyst nematode, one of the state’s true silent yield robbers.

SCN is a plant-parasitic roundworm that has been a problem in Nebraska since 1986, says Dylan Mangel, Extension plant pathologist at the University of Nebraska-Lincoln.

“Since then, it has expanded slowly but steadily, as we would expect from a soilborne disease, and now it has reached those midway counties butting up against the Sandhills, and is still spreading in the southern part of the state toward the west in the southern and the south-central region,” Mangel says.

SCN is widely found in fields across the country, Mangel says, and it has a 30% positivity rate in fields. This pest is easily spread into adjacent fields as equipment moves from field to field.

Management against SCN

This silent yield killer can be detrimental to yields because the plant usually does not show symptoms once it has been infected.

“Unfortunately, fields can lose up to 30% yield with no noticeable aboveground symptoms,” Mangel says. “That is a bit of an extreme situation, but in most cases, you might be losing 3% to 12% yield, and it is that consistent yield loss that adds up across farms and the state.”

Related:5 ways to control soybean cyst nematode

In counties where soybeans are widely grown, farmers should be the most concerned about this pest because the population can grow rapidly. Mangel recommends that farmers be careful when moving soil, especially to fields that do not have SCN.

The type of soil in fields growing soybeans can also be an indicator of where SCN might show up.

“A big predictor of how well SCN will do in a soil is the sand percentage,” Mangel says. “The nematodes need some sand in there to help open pore size and help them move around. Unfortunately, we have a lot of sandy soils in Nebraska.”

Mangel also mentions that SCN does well at neutral pH, and if you have high pH soils, the impact is amplified.

The most effective ways to manage SCN in the soil are to have a crop rotation with a non-host crop, choose a soybean variety that is resistant to SCN, use a nematode protectant seed treatment and test soils for SCN.

“Fortunately, corn is a non-host crop that works well with standard rotations and in the Midwest,” Mangel says.

When looking to buy seed for the upcoming year for fields that are affected by SCN, Mangel recommends two resistance sources, PI88788 and Peking.

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“PI88788 has been used widely since the late 1990s and is waning in its effectiveness because of overuse. The nematodes have evolved to find ways to overcome that resistance source, making it less effective,” Mangel explains. “While PI88788 has some remaining effectiveness, we are recommending that you rotate between available resistance sources.”

Mangel recommends talking to your local seed adviser to see what nematode protectant works well in your area.

“The last management step is retesting,” he says. “Because we cannot see how these populations are changing in the soil, to test if your management is working, take advantage of testing programs available in your state and make sure your population is decreasing.”

Take advantage of free testing

One way that farmers can help manage SCN in soils is by testing. NSB is funding this essential service that can help detect and manage SCN.

According to NSB, SCN costs U.S. soybean producers an estimated $1.5 billion in lost yields annually.

Levels of SCN are at their highest postharvest, so now is a crucial time to test your soils. There are three simple steps to submit your soils for testing:

When looking to see what soil to test, consider sampling areas that have unexplained low yields or stunted growth.

Farmers can submit their soil samples to the UNL Plant and Pest Diagnostic Clinic, 1875 N. 38th St., 448 Plant Sciences Hall, Lincoln, NE 68583-0722. Make sure to include the following:

By using this free testing service and taking proper management steps, farmers can better fight against the harmful effects of SCN.