Sudden Death Syndrome is first noticeable as small yellow spots on soybean leaves. As the disease develops, the yellow spots increase in size, eventually turning brown and drying out. In striking contrast, veins of leaves usually remain green.
Symptoms begin on upper leaves, and as the disease progresses, symptoms develop on lower leaves.
In severe cases, plants may lose their leaflets. Petioles, the stalk by which the leaflets are attached to the plant, remain on the plant. Root systems of infected plants may be discolored and smaller than those of healthy plants, and the nitrogen-fixing nodules on the roots may appear rotted. The vascular tissue, which transports water and nutrients throughout the plant, is discolored, from tan to gray to brown. The pith, the center of the stalk, remains white.