They needle into roots to draw out moisture and the very nutrients soybeans need to thrive. Although unseen to the naked eye, soybean cyst nematode (SCN) is the No. 1 most devastating pest in soybeans, stealing billions annually. And now, farmers’ primary method of defense is crumbling.
“We used the same resistance mechanism for two decades—you wouldn’t do that with herbicides and not expect resistance,” says George Bird, a nematologist at Michigan State University and another SCN Coalition leader. “We’ve seen more issues with resistance in the past eight years. We want to see other forms of resistance made available.”
SCN is resistant to PI 88788–the most common form of genetic resistance–in 90% of Iowa fields and is increasing resistance across the country. Farmers need more tools in the toolbox to fight the pest. While seed treatments continue to develop, genetic resistance needs to be improved. Recent yield advancements might provide another form of genetic resistance to the yield-robbing pest.
Another genetic option is expanding its product offerings—Pioneer’s soybeans with resistance to SCN from Peking. This option provides farmers with another, effective, genetic tool against this pest.
“Peking offers resistance to more SCN races,” says Don Kyle, Pioneer soybean breeding lead. “We sold our first Peking product in 1990 and have been actively involved in breeding since the 1980s. Pioneer continues to build a robust portfolio of varieties with industry-leading yield potential and strong agronomics.”
According to some, genetics have faced challenges when it comes to yield.
“Historically, varieties with the Peking source of resistance haven’t yielded quite as well as varieties with the PI 88788 source of resistance,” says Greg Tylka, Iowa State University nematologist. “But that’s only true in fields with the nematode well controlled by PI 88788. We’re in a different world these days.”
“We can’t completely abandon varieties with PI 88788, but we need to try to maintain whatever activity it has left by using an integrated approach,” Tylka adds.
The need for SCN control is more pertinent than ever before.
“Pretty much every field has nematodes that are not being controlled by the PI 88788 gene,” says Thad Haes, Valent seed protection business manager. “Nematodes survive in the soil so it’s not a one year fix, it takes implementing a system.”
Fields with PI 88788 are yielding about 14 bu. per acre less than when SCN was controlled. According to the SCN coalition, less than one in 10 SCNs should be able to reproduce to prove you have adequate control. Now many farms have more than 50% of the SCN population successfully reproducing in fields with PI 88788 genetic resistance—which represents approximately 95% of all resistance.
The pest can mimic other ailments and tends to congregate in low areas of the field—which means it can easily be mistaken for water damage. In addition, early attacks from SCN open soybeans up to a host of other diseases like sudden death syndrome, and others. This happens because the plant’s immune system is already compromised from the nematode so it can’t ward off attacks from other pests as effectively.
SCN is a powerful pest:
- It spawns a new generation every 24 days—that’s up to six generations each summer
- Every dead female can contain 250+ eggs
- SCN was imported to the U.S. and first identified in North Carolina 1954
- PI 88788 resistance was found in 1962 and the first variety with SCN resistance was released in 1978
Consider your options with SCN to make sure you’re protected. Look at genetic, seed treatment and soil applied options to gain control.