Update on SCN Management

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Soybean Cyst Nematode (SCN) remains the #1 most damaging soybean pest in North America. This pest has been called the “silent yield robber” because fields with no visible symptoms can experience a 10% yield loss.

Recently I attended a crop management seminar in Ames, Iowa. Iowa State University (ISU) Extension Nematologist Dr. Greg Tylka presented research findings showing that yield loss to SCN under severe infestations can be as much as 50 percent. Although most farmers don’t experience that level of damage, the trend is that SCN is affecting more acres than before.

There is another alarming trend showing up in Iowa and in other states that make up Latham Country…many SCN populations are becoming resistant to PI 88788, which is the main source of genetic resistance.

Dr. Tylka and his staff have been conducting yield trials since 1991 in Iowa with SCN-resistant soybeans. More than 95% of the soybeans entered in those yield trials carry the PI 88788 gene which has, historically, been the best source of SCN resistance for U.S. farmers. From 1991 to 1999, almost all the SCN populations in these trials reproduced below 10% (which is considered excellent) with the PI 88788 gene. Starting in 2000, however, that resistance started to falter. In 2015, there were no PI 88788 soybeans that held the reproduction level of SCN below 10%!

Over time, there has been a gradual reduction in yield while using the PI 88788 resistance. This trend was rather predictable as we’ve seen the same thing happen with weed resistance to various herbicides. Going forward, we know that the usefulness of PI 88788 will continue to decline.

Here at Latham Hi-Tech Seeds, we are working with breeders to bring in cultivars that have Peking resistance in hope that these will perform well against SCN and produce acceptable yields. Along with that, we will continue to monitor the various new seed treatment options as they become available. Products like Clariva®, VOTiVO®, Aveo™ EZ, NemaStrike™, ILeVO® and others may prove helpful as we try to manage this very serious soybean pest.