The soybean cyst nematode (SCN) was a serious yield-limiting pest of soybeans throughout Iowa in 2006. It caused severe damage in areas of Iowa that received less-than-normal rainfall. This nematode is widely distributed throughout the state and does not increase its numbers extraordinarily (i.e. does not flare up) in dry years. The nematode has excellent long-term survival and its population densities build up each year that susceptible soybeans are grown, regardless of the precipitation that occurs. Research in Iowa has shown that up to 40% yield loss can occur without the appearance of any above-ground symptoms.