A survey of more than 40 seed companies has re­vealed an increase from a year ago in the number of soybean varieties with Peking soybean cyst nematode (SCN) re­sistance, a positive step as Iowa farmers continue to battle a soybean root parasite that robs crop yields and profits.

There are 866 SCN-resistant varieties and five blends available for 2024, 48 more than 2022 and 40 more varieties identified as providing Peking SCN resistance, the most ever. All 866 varieties possess SCN resistance from either PI 88788 or Peking breeding lines.

The increase in the number of Peking varieties is noteworthy, said Iowa State University plant pathologist Greg Tylka. Two decades of primarily utilizing PI 88788 varieties have led to SCN adapting and reproducing — essentially becoming resistant to the resistance. 

The Peking form of resistance has emerged as an effective “tool in the toolbox” ...