Pythium wilt is usually first noticeable in mid August, when leaflets and petioles on growing limbs wilt. At first the plants wilt only during hot days, then recover at night or during wet weather. Wilted leaves first appear yellow to light green and have margins that are curled or puckered. These leaves may eventually turn brown and shed prematurely. Occasionally, plants develop permanent wilt symptoms and die as a result of this disease. Plants that wilt early in the season usually have a high number of pods rotted by the causal fungus.

The root systems of severely wilted plants are stunted but not severely rotted as is characteristic of Cylindrocladium black rot. The cause of wilt is easily seen by cutting into the taproot and exposing the abnormal, gray to brown vascular system. This discoloration will be most intense in the taproot and slowly fade as it extends upward into the wilted stems. Rye and rye grass are hosts of this fungus and when used as a cover crop in a peanut-corn-peanut rotation may result in a build-up of this fungus in soil.