Soybean Cyst Nematode (SCN) was first found in the US in North Carolina in 1954 and now is considered the most serious soybean pest in the US. A microscopic roundworm, the nematode now occurs in all major soybean production areas including Wisconsin. It is believed that SCN was first discovered in southeastern counties of the state in the early 1980s. Since soybean acreage has increased dramatically since then, so has the spread of SCN. SCN causes no specific symptoms and its effects are often not dramatic. Many growers do not know they have a problem until a severe infestation develops. SCN is detrimental to soybean because it lowers yields by as much at 50% and compromises plant health by making the soybean more susceptible to other pathogens and moisture stress.