Take the Test and Beat the Pest!

Fig 1By robbing farmers of more than 100 million bushels annually, Soybean Cyst Nematode (SCN) is estimated to be the #1 yield-robbing soybean pest or disease in the United States. Farmers may scream over lost yield this fall, but SCN is considered a “silent yield robber” due to a lack of above-ground symptoms in most fields.

Immediately after harvest is the best time to take soil samples for SCN. Several universities have programs that offer free soil samples to evaluate SCN, so check with your local Extension office to see if you qualify.

Think SCN isn’t a problem in your fields? Think again! Dry soil conditions, especially early in the growing season, can greatly increase the effects of SCN infestations. I received numerous calls in June and July about yellow, stunted soybeans. Most farmers suspected Iron Deficiency Chlorosis. Upon further inspection, SCN was almost always present and in larger numbers than previously observed. When I asked whether these farmers had taken a recent soil sample for SCN, most had not. They admit to mostly relying on SCN-resistant varieties to control or minimize the losses from this pest.

We have known for years that PI 88788 is gradually losing its efficacy against the pest, and more than 95% of SCN-resistant soybeans in America have PI 88788 as the source of gene resistance.  Since 1997, a team of researchers at Iowa State University led by Dr. Greg Tylka has conducted annual in-field trials with hundreds of SCN-resistant varieties. They measure agronomic performance and SCN population densities from planting until after harvest.

Scientists have determined that to be effective, SCN-resistant varieties must maintain less than a 10% reproduction rate of SCN during the growing season.  Since 2004, Dr. Tylka and his team have noticed that the average of all PI 88788 varieties in their trials have gradually exceeded that threshold. They have also noted that the average yield of those varieties has decreased as the SCN reproduction has increased. For more information on these studies, visit www.isuscntrials.info. Other land-grant university researchers have reported similar findings.

To effectively manage SCN in the future, soybean breeders are focusing on other sources of gene resistance. Your Latham Soybean Product Team is continually evaluating and searching for opportunities to bring new, better resistant varieties to our lineup. We also are evaluating several seed treatments for battling this pest. Saltro®, our seed treatment product for SDS protection, is also noted to have activity against SCN.  More information from our Latham Elite trials will be available post-harvest.

“TAKE THE TEST.  BEAT THE PEST.” is a slogan/campaign by The SCN Coalition™ and funded by the Soybean Checkoff and is designed specifically to promote awareness of SCN. These microscopic roundworms, which infect the roots of soybeans and other plants, can be present in a field for years before above-ground symptoms are visible. We encourage you to take the test this season, so you can plan accordingly for the future.