Iowa State University researchers conducted studies on more than 150 soybean cyst nematode-resistant varieties planted all over the state of Iowa.
The soybean yield, beginning and end of season soybean cyst nematode (SCN) soil egg numbers were measured in the experiments supported by a soybean checkoff funding through a grant from the Iowa Soybean Association.
Some varieties of soybeans planted have only some of the full set of SCN-resistant genes, but it is necessary for the varieties to have the complete set of SCN-resistant genes to ensure the best chance of not having a problem with SCNs. The fully SCN-resistant soybean varieties had greater yields and lower SCN soil egg population densities than the varieties planted that were still susceptible to SCN.
However, the Midwest features resistance genes from a breeding line or source of resistance called PI 88788 which is causing all varieties of soybeans to be slowly losing their SCN-resistance. The recommendation for managing the buildup of SCN on PI 88788 SCN resistance is a multi-faceted approach; including growing nonhost crops and using nematode-protectant seed treatments on seeds of resistant soybean varieties.
The experiment was completed in December and a full final report was included as a special insert of the Jan. 16 Iowa Farmer Today. It is also available online at isuscntrials.info and through the Iowa State University Extension and Outreach Online Store.