Anthracnose of soybeans

Colletotrichum truncatum

The most common symptoms are seen late in the season as the plants approach maturity. Irregular brown spots develop in a random pattern on stems and pods. The infected areas are covered with tiny black spines (setae) that can be seen with a 10X hand lens. Brown cankers can appear on petioles and cause defoliation. Infection of pods results in few or small seeds per pod. Infected leaves may develop brown veins and curl up. In older plants, the stems, pods, and leaves may be infected without showing symptoms until the weather is warm and moist or plants reach maturity. Infected seeds may have no symptoms or may develop brown or gray areas with black specks. Seeds infected by anthracnose may not germinate. Infected seedlings develop dark, sunken cankers on the cotyledons, epicotyl, and radicle that cause damping-off.

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