Soybean anthracnose

Soybean anthracnose is a significant fungal disease caused by Glomerella glycines (the asexual state is Colletotrichum truncatum). This pathogen affects soybean plants globally, causing severe yield losses by attacking various parts of the plant throughout the entire growing season.

The host range is primarily focused on soybean crops, although the pathogen can survive in crop residues and infect alternative legume hosts. The fungus is seed-borne and can remain viable in infested soil or debris for extended periods, serving as a primary source of infection in subsequent years.

Symptoms typically manifest as dark brown or black lesions on stems, pods, and leaves. Under humid conditions, small black fruiting bodies called acervuli appear on the necrotic tissues. In severe cases, the disease leads to premature leaf drop, stunted plant growth, and the development of poorly filled or rotten pods.

The development of Glomerella glycines is heavily favored by warm temperatures and high humidity, particularly during the reproductive stages of soybean development. Rain splashes facilitate the rapid spread of conidia from lower leaves to the upper canopy, significantly increasing the severity of the outbreak.

Integrated pest management (IPM) is essential for effective control. Key strategies include the use of certified, disease-free seed, seed treatments with systemic fungicides, and crop rotation with non-host species. Additionally, managing crop debris through tillage and applying foliar fungicides during critical stages can reduce the inoculum load and protect the yield.