How does the soybean cyst nematode spread?
SCN can move only a few centimeters in the soil by itself. However, soil containing cysts and eggs can be moved long distances within a field or between fields by any means that moves soil. Soil movement in runoff water, by wildlife, and in windborne dusts are all natural mechanisms that spread SCN. Since the nematode cysts can survive passage through a bird's digestive system, birds may spread SCN over long distances. Human activities that move soil between fields on equipment, tools, and vehicles are probably the primary means by which SCN spreads. Seed contaminated with soil peds infested with SCN is another way SCN can move long distances.
In Minnesota, SCN has been reported throughout soybean-producing areas in the southern and central regions of the state. In recent years, the nematode has been found in several counties in the northern soybean-growing areas in Minnesota. Thus, the colder climatic conditions will not limit the spread of the nematode in the Red River Valley where soybean production is increasing. Indeed, frequent flooding in the Red River Valley may favor rapid spread of the SCN in that area.