November 30, 2020

Are Nematodes Robbing Your Soybean Yields?

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In once local field, MaxYield’s Dan Stokes could observe nematodes on soybean roots that were 2. 5 to 3 feet deep, all without using a magnifying glass.

If it seems like your soybean yields are at a standstill, you’re not alone. The biggest culprit might be something so tiny that it’s easy to overlook—soybean cyst nematode (SCN).

“While we’ve got more elite seed genetics and better seed treatments today than we did in 2005, local field data shows we’re still no better yield-wise, on average, than we were then,” said Dan Stokes, a MaxYield seed solutions specialist. “I think we’ve got more challenges with nematodes than people realize.”

SCN has been called the number one pest of soybeans in Iowa. Nematodes are among the most populous creatures on the planet, so it’s no surprise they reside in nearly every field. Nematodes also reproduce quickly, creating several generations in season.

SCN tends to show up in lighter, sandier parts of the field and in high pH areas, Stokes said. SCN can be tricky to detect, however, because its symptoms often mimic iron deficiency chlorosis.

The Society of Nematologists estimates that plant-parasitic nematodes cause more than $3 billion worth of crop losses annually. “We’ve seen a gradual increase of SCN over several years, and the pests are difficult to manage,” said Loren Giesler, a University of Nebraska-Lincoln Extension plant pathologist.

Pests can stay in the soil for 10 years

SCN feeds on roots, robbing the soybean plant of nutrients. SCN also causes root wounds that allow diseases and fungi to invade the plant. The severity of crop damage and yield loss depends on crop rotation and the soybean variety planted.

University researchers note that several recent changes in farming practices are influencing greater SCN populations in many fields. First, growers used to use some insecticides that also had activity on nematodes, however, we no longer use these.

Corn-on-corn or bean-on-bean rotations are another big influence. “Nematodes can stay in the soil for 10 years or more when soybeans aren’t in the rotation,” Stokes said.

Sampling for nematodes is difficult, Stokes added. Nematodes go deep in the soil when conditions are hot and dry, making it tough for traditional sampling methods to reveal the pests. “Hotter soils in the late summer are also why we had fewer SCN problems in 2013,” Stokes said.

Is it time for new seed treatments?

If you’re counting on nematode-resistant soybean varieties to prevent all SCN damage, you might be disappointed, Giesler said. He sees a stronger future for nematicides on soybeans.

So does Stokes, who recommends some of the new seed treatments on the market. “We’re planting earlier, so the beans need to be treated to protect against nematodes.”

Stokes recommends the Poncho®/VOTiVO® seed treatment, which uses a biological mode of action to protect soybean plants from pests during critical early development stages. Poncho/VOTiVO contains a unique bacteria strain that lives and grows with young soybean roots, creating a living barrier that prevents nematodes from causing damage.

“When nematodes come looking for something to eat, there are no signs of the roots available, because the roots are surrounded by Poncho/VOTiVO,” Stokes said. “As the bacteria multiply, you also get more protection as the season goes along.”

Trials have shown a 2- to 8-bushel yield advantage with Poncho/VOTiVO, depending on soil conditions and other factors. “It’s about a $4- to-$5-per-acre investment that can deliver a 2:1 return,” Stokes noted. “Take a hard look at this option when you’re getting your beans treated, and at least consider treating a portion with Poncho/VOTiVO.”

In 2014, MaxYield will conduct more split treatments at local test plots to study Poncho/VOTiVO and other seed treatments. The goal? Find practical, proven solutions to address the nematode challenge and push soybean yields beyond 50- to 55-bushels per acre into the 70+ bushel range.

“We’ve got the genetic potential to make this happen,” Stokes said. “When we stop nematodes right from the start, we can get serious about growing higher soybean yields.”

For more information on controlling SCN, contact your MaxYield seed solutions specialist or MaxYield agronomy specialist.


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