Occasionally, bright yellow dots may be seen on the leaves. When the plants are infected early, they may be severely stunted and spindly. Seed set is usually affected. The varieties Kentucky Wonder, Corbett Refugee, Creaseback and varieties bred from them have an entirely different set of symptoms. The top leaflets wilt during the bloom period.
Plants appear grayish green in color.
Later, the whole plant wilts and eventually dies. The roots appear dark, and dark markings to appear on the lower stem and the petioles. On some varieties, a net-like browning of the veins occurs on the leaves. This disease is spread from plant to plant by at least 12 aphid species. Many of these feed on alfalfa, clover, and rye.