Eggs do not develop without fertilization by the male. Field Symptoms Symptoms of SCN injury can easily be confused with other soybean production problems including potash deficiency, herbicide injury, charcoal rot, drought, Phytophthora root rot, and soil compaction. Even when excellent conditions exist, high numbers of nematodes may reduce yield without showing obvious symptoms. The first noticeable symptoms are roughly circular spots in the field. Soybean plants may show signs of stunting, yellowing, or nutrient deficiency.
Roots have fewer feeder roots and nitrogen-fixing root nodules.
Heavily infested plants may die directly from nematode feeding or from the combination of nematodes plus nutrient deficiencies or other diseases. In heavy infestations, symptoms are most evident by the time plants are 6 to 12 inches tall. In lighter infestations, symptoms may not appear until the beginning of podding. Infested areas may increase in size annually and become oval-shaped, expanding in the direction of tillage. Damage is usually most severe in the center of infested areas, becoming less severe toward the margins.