Known Distribution of the Soybean Cyst Nematode, Heterodera glycines, in the United States and Canada, 1954 to 2017

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, remains a major yield-reducing pathogen of soybeans, Glycine max L. Merr., in North America more than 60 years after its first discovery in the United States, in North Carolina in 1954 (Winstead et al. 1955). The nematode recently was ranked as the most damaging soybean pathogen in the United States and Canada (Allen et al. 2017). SCN is believed to have been introduced to the United States from Asia (Noel 1992; Riggs 2004), and as an introduced pest, knowledge of the distribution of SCN can be helpful in identifying areas where scouting and management efforts should be focused. Such information is especially important for SCN because yield-reducing infestations can occur without obvious above-ground symptoms (Wang et al. 2003)

Distribution of the Soybean Cyst Nematode, Heterodera glycines, in the United States and Canada: 1954 to 2014

The soybean cyst nematode, Heterodera glycines Ichinohe, is considered the most damaging pathogen of soybean (Glycine max (L.) Merr.) in the United States and Canada (6). This nematode also causes considerable yield loss in many other soybeanproducing countries in the world. Heterodera glycines was first discovered in the United States in New Hanover County, North Carolina in 1954 (5) and is believed to have been introduced from Asia (3). In 1987, the nematode was discovered in Kent County, Ontario (1). At various times since these initial discoveries, maps were created of the counties in the United States and Canada that were known to be infested with the nematode