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Why you should test for nematodes this fallWhy you should test for nematodes this fall

Find out if soybean cyst nematodes could be holding you back from higher yields.

Tom J. Bechman

September 18, 2023

3 Min Read
A man holding a soil sample over a black bucket
THE NEMATODE SEARCH: You could have significant numbers of nematodes even without seeing symptoms. Managing SCN begins with sampling soils to determine existing levels. Tom J. Bechman

You can’t manage what you don’t know. So, the starting point for managing soybean cyst nematodes is sampling soils to determine if SCN are present, and if so, at what levels.

“The best time to sample for soybean cyst nematode is outside the growing season,” says Nick Tinsley, technical field rep for BASF, based near Champaign, Ill. He works exclusively with the BASF portfolio of seed treatment products.

“We encourage growers to pull soil samples to test for soybean cyst nematode,” he says. “It’s especially important if a field hasn’t been sampled in three years or more. You need a baseline for SCN.”

Just because you haven’t seen symptoms doesn’t mean there aren’t nematodes in your soils, he adds. Even where there are no visible symptoms, nematodes working below the soil can steal several bushels per acre annually.

BASF summarized two years of nematode sampling by farmers and BASF personnel across the Midwest. About 780 samples were pulled — some from fields where nematode problems were suspected, and some from fields where no symptoms were visible, Tinsley says. The average number of cysts per 100 cubic centimeters of soil was 2,600, which is considerably higher than the 500 per 100-cc threshold where soybeans are at risk by nematodes.

“SCN also drives sudden death syndrome, although the two aren’t directly related,” Tinsley says. “We know that when nematodes attack soybean roots, plants are more vulnerable to SDS.”

Sampling soils

Pulling soil samples to send for analysis for SCN after harvest is straightforward, Tinsley notes. Use a regular soil sampling probe and collect samples from across the field. Just as in soil sampling, walk in a random pattern across the field, collecting a dozen or more cores that you can combine into one sample representing the field.

Tinsley advises against drying samples. Instead, package and send them as soon as possible to the lab of your choice. Allowing samples to sit for an extended period could skew results.

Managing cyst nematodes

Soybean seed treatments are just one tool for managing SCN, but they are an important one, Tinsley says. BASF offers Ilevo, with efficacy against SDS and SCN.

Now, BASF also offers Poncho Votivo Precise for soybeans. Poncho provides an active chemical ingredient targeting insects, while Votivo is a unique biological agent targeting nematodes. Initially a seed treatment for corn, Poncho Votivo was labeled for soybeans over a decade ago.

“Poncho Votivo Precise offers a unique active ingredient, which is more geared to combating cyst nematode in soybeans,” Tinsley explains. “We believe it will be another important tool for growers.”

Seed companies continue working on resistance to cyst nematodes, but at the same time, nematodes develop resistance of their own. That makes some varieties that once offered strong resistance less effective. Soybean varieties carrying the Peking gene tend to be more effective against today’s races, but only a small percentage of varieties on the market have that resistance gene.

Resistance to SCN through a Bt gene is under development, but it’s a few years away, Tinsley says. Meanwhile, he urges growers to know their SCN levels and use seed treatments and other tools to manage the pest.

Read more about:

Soybean Cyst Nematode

About the Author(s)

Tom J. Bechman

Editor, Indiana Prairie Farmer, Farm Progress

Tom J. Bechman is editor of Indiana Prairie Farmer. He joined Farm Progress in 1981 as a field editor, first writing stories to help farmers adjust to a difficult harvest after a tough weather year. His goal today is the same — writing stories that help farmers adjust to a changing environment in a profitable manner.

Bechman knows about Indiana agriculture because he grew up on a small dairy farm and worked with young farmers as a vocational agriculture teacher and FFA advisor before joining Farm Progress. He works closely with Purdue University specialists, Indiana Farm Bureau and commodity groups to cover cutting-edge issues affecting farmers. He specializes in writing crop stories with a focus on obtaining the highest and most economical yields possible.

Tom and his wife, Carla, have four children: Allison, Ashley, Daniel and Kayla, plus eight grandchildren. They raise produce for the food pantry and house 4-H animals for the grandkids on their small acreage near Franklin, Ind.

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