The first visible aboveground symptom is the wilting of one leaflet or more on a single leaf The oldest leaves usually show symptoms first, and then wilt develops progressively in the younger leaves. In Greenhouse plants that become infected during January February and early March show sudden wilting of several leaves, which become characteristically patterned with bright autumnal colors-yellow and brown; these plants often die in a few days. During late spring and summer, infected plants usually survive in a considerably stunted, wilted condition. A heavy watering seems to induce rapid upward movement ofthe fungus in infected plants. In the field, symptoms appear as wilted, V-shaped, yellowed areas extending in from the margins of the leaves. Frequently, the first symptoms appear on leaflets on only one side of the leaf The oldest leaves and yellowed areas die progressively Although the whole plant rarely dies, it remains unproductive.
The causal fungi inhabit the soil and enter the plants through the roots. From the roots they advance through the woody tissue, where they usually cause a brownish discoloration in the vascular system, and then spread into the stem. The degree of browning of the water-conducting tissues of the stem varies, depending on the susceptibility of the plants and the softness of plant growth.
