Soybean cyst nematodes (SCN) rob U.S. soybean farmers of between 100 and 150 million bushels of yield, depending on the year, more than any other disease or pest, according to a soybean-checkoff-funded survey.

The checkoff collaborates with researchers like Terry Niblack, University of Illinois, to verify SCN resistance in seed varieties. At the urging of the United Soybean Board (USB), Niblack, along with other Illinois researchers, began industry collaboration in 2007 to determine the ideal standards for SCN resistance. The findings were accepted by the National SCN Conference. The new standards could ensure that seed company varieties claiming to be resistant to SCN really do control SCN infestation.

“Several years ago we tested many varieties and found that two-thirds of the varieties labeled as SCN-resistant were not really resistant, according to our assessment,” says Niblack. “Now, over 85% of the varieties labeled as SCN-resistant show resistance. The standardization has the effect of encouraging the companies to correctly label their seed.”

The standardization also provides soybean farmers with more information on SCN, allowing them to make better decisions to control this yield-robber. Different Heterodera glycine (HG) types or races of SCN exist and varieties that control one type may not control other types.

“Most SCN-resistant varieties only cover one HG type, so if you have another type in your fields, you may not get adequate control,” says Jim Legvold, USB director and soybean farmer from Vincent, IA. “We are also seeing HG type shift in SCN, so knowing which seeds provide resistance to which HG type will help U.S. soybean farmers make better decisions.”

To best utilize this information, farmers first need to know what type and level of infestation of SCN they’re facing. Farmers can find this out through soil tests, with most land-grant universities offering this service.

Niblack receives many requests from other states to do type testing. Legvold has first-hand knowledge of how the small investment for the soil test pays for itself in allowing him and other U.S. soybean farmers to better control SCN.

“The standardization allows soybean farmers to compare apples to apples,” says Niblack. “With this system, farmers will know seed meets the SCN-resistance standards. Now the burden falls on the seed companies to prove their resistance with this label.”