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Published on January 21, 2025
University of Missouri Extension Warns Against Sole Reliance on Seed Treatments for Managing Soybean Cyst NematodeSource: University of Missouri

Soybean cyst nematode (SCN), a major threat to soybean crops across the U.S. and Canada, cannot be effectively managed by relying solely on seed treatments, according to recent studies from the University of Missouri Extension. Mandy Bish, who serves as both a state plant pathologist and the director of MU's nematode clinic, SCN Diagnostics, has emphasized the importance of diversifying strategies to combat this persistent issue. While treatments like ILeVO have been shown to decrease high SCN levels in field trials, they fall short in consistent management, particularly in areas with moderate infestations.

For over 30 years, soybean growers have placed their trust in the PI 88788 soybean trait as the principal line of defense against the organisms. Despite the fact that more than 95% of soybean varieties grown in Missouri have historically incorporated this resistance, Bish warns against banking on any singular tactic for too long. Data suggests that SCN's ability to adapt poses a serious threat to the effectiveness of such resistances over extended periods. In fact, preliminary findings indicate that Missouri's SCN populations are starting to reproduce on plants with the Peking resistance trait, signaling potential challenges ahead.

Bish's research isn't just about cultivating crops—it's focused on cultivating hope. In studies conducted by her team, the Peking-type resistance not only substantially reduced SCN populations but also boasted a yield increase surpassing 5 bushels per acre over the more conventional PI 88788 and other susceptible varieties in environments with high SCN pressure. However, Bish cautions farmers, stating, "Thirty years is a long time to rely on one management tactic, and we cannot afford to use Peking soybean in the same way."

In response to these challenges, Bish advocates for an integrated approach to battling SCN, a stance that involves strategic rotation with non-host crops like corn and planting a mix of both PI 88788 and Peking-resistance soybean varieties. To ensure that these efforts are as effective as possible, she further recommends soil tests both before and after each growing season. This practice helps to gauge the success of different management strategies and adjust plans as necessary to keep the persistent pest in check. As the battle against SCN rages on, it is clear that adaptability and integrated tactics may prove to be farmers' best allies in their ongoing quest for crop health and productivity.