The disease can cause 100 percent yield reductions when cool, wet weather conditions persist during the growing season. Anthracnose symptoms may show up on leaves, stems, pods, and seeds of bean plants. Lesions on stems are sunken oval cankers, extending up and down the stem. Cankers range in color from brown to black with purple to brick-red borders, giving the lesion an eyespot appearance. Bean stems weakened by cankers are often more susceptible to damage from cultivation and strong winds.
Lesions are more common on leaf petioles and on the lower surface of leaves and leaf veins.
Lesions are elongate, angular, and brick red to purple, becoming dark brown to black with time. Lesions often follow the veins on the lower leaf surface. When severe, angular dead zones may form on the upper leaf surface giving the plants a ragged appearance. The most easily recognized symptom of anthracnose on beans occurs on the pods. Small, reddish-brown elongated spots form initially.