The nematode may have been introduced into the United States several times during the late 1800s in soil imported from Asia for the purpose of obtaining bacteria to nodulate soybean roots. SCN can be spread by anything that moves soil: wind, water, animals (especially birds) and machinery. Documenting the economic impact of SCN is difficult because many producers suffer declining yields for several years without knowing that they have SCN. Planting the SCN-resistant variety Forrest in the southern United States on farms with known SCN infestations prevented $401 million in crop loss during 1975-1980, while the cost of developing Forrest.
