The soybean cyst nematode (SCN) is one of the most serious soil-borne pathogens of soybean in Iowa and throughout the Midwest. Juveniles of this microscopic worm hatch from eggs in the spring, then burrow into soybean roots, where they attach to the vascular tissue of the plant and feed (Figure 1). Developing SCN females get progressively larger as they mature, until their fully expanded, lemon-shaped bodies rupture out of the root and become visible on the root surface.