Managing two soybean pests to optimize yield

Soybean cyst nematode (SCN), Heterodera glycines Ichinohe, and soybean aphid (SBA), Aphis glycines Matsumura, are significant pests of soybean and can cause substantial yield losses.  Farmers can now use native, host-plant resistance (HPR) to manage SCN and SBA.  Nematicidal and insecticidal seed treatments can further suppress pest activity.  We studied combinations of host-plant resistance for SBA and SCN with different seed treatments.  Our goal was to determine how these integrated pest management approaches affect soybean yields and pest abundance.  The field study was replicated at two different locations in Iowa in 2013, 2014, and 2015.    We found that varieties of soybeans with HPR suppressed populations of SBA and SCN.  However, the use of a nematicidal and insecticidal seed treatment did not provide additional pest suppression when used with HPR.  In addition, we found that seed treatments rarely provided significant improvements to yield on naked seed.  We recommend using HPR for SCN and SBA for consistent yield protection.