SCN Testing Is More Important Than Ever

Soybean Cyst Nematode ( Sam Markell )

Flooding this spring won’t just devastate fields and productivity this year—it’ll affect your fields for years to come. You’ll battle not only compaction and out-of-control weeds but possibly soybean cyst nematodes (SCN), too.

It’s more important than ever to test fields for SCN this year.

“With early season flooding, before seed was even in the ground, how did the soil move?” says Kaitlyn Bissonnette, University of Missouri Extension professor and director of SCN Diagnostics. “Where did that soil deposit?  That matters because the soil could contain cysts that float and move with flooded soils.”

“Your map from testing for SCN last year won’t reflect any fields that were flooded this year,” Bissonnette adds. “It’s more important to test this year than in other years because of that flooding.”

Cysts don’t die in water. According to research from the University of Arkansas, SCN juveniles can survive in water up to 630 days and possibly longer. In flooded soil they survived seven to 19 months depending on soil type. SCN eggs can survive through dormancy for years even without soybeans.

“They absorb oxygen through their body wall or cuticle, which is made almost exclusively of proteins,” says Greg Tylka, Iowa State University nematologist and leader of the SCN Coalition. “Waterlogged soils may have greatly reduced levels of oxygen. But many plant-parasitic nematodes, including SCN, can survive long periods of time with little oxygen.

“Typically, the eggs are more tolerant of environmental stresses than hatched juveniles,” Tylka adds. “So, it’s likely that SCN eggs in infested fields are not adversely affected by waterlogged soils either.”

BMPs When Sampling for SCN

For more information about where and how to sample for SCN and where to send samples visit: https://www.agweb.com/article/test-for-soybean-cyst-nematode--NAA-sonja-begemann

The Future of SCN Resistance Nears

Right now, there are two soybean cyst nematode (SCN) resistance options on the market (not including any seed treatment options): PI88788 and Peking. The former is rapidly losing effectiveness in some areas and the latter could fail if selection pressure grows too strong.

Bottom line: farmers need more SCN resistance options.

Fortunately, researchers have identified new resistance genes. Brian Diers, plant breeder at the University of Illinois, found two new resistance genes from wild soybean varieties. These are being bred into commercial varieties for testing, where they’ve proven to be highly effective.

“We found that by combining genes from different resistance sources we could obtain much higher levels of resistance compared to using one source,” Diers says. He’s created a four-gene stack to control the pest.

In addition, farmers could soon see the industry’s first biotech SCN resistance trait hit the market from BASF.

“BASF is developing an SCN trait that would provide tolerance against cyst nematode in soybean and protect more yield for the farmer,” says Marc Hoobler, BASF soybean agronomy lead. We’re also testing it against other nematode species.”

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