Soybean anthracnose

The causative agent of this disease is the fungus Colletotrichum temperatum, which belongs to the class Ascomycetes. It is responsible for soybean anthracnose, a significant fungal disease that can lead to yield losses in soybean-producing regions worldwide. The pathogen affects the plant at all stages, from seedling emergence to maturity.

The primary host for this fungus is soybean Glycine max. The pathogen infects all aerial parts of the plant, including stems, petioles, leaves, and pods. In severe cases, the fungus colonizes the vascular tissues, leading to wilting, stunted growth, and pod abortion, which significantly impacts the overall crop yield.

Key symptoms include the development of dark, sunken, irregular lesions on stems and petioles. As the disease progresses, acervuli—small black fruiting bodies—form within these lesions. Under high humidity, these structures produce masses of spores, often appearing as a pinkish or greyish mold, which aids in the secondary spread of the infection.

Colletotrichum temperatum thrives in warm, humid conditions, particularly during the flowering and pod-filling stages. The pathogen overwinters on crop debris and in the soil. Furthermore, it is a seed-borne disease, meaning that infected seeds serve as a primary source of inoculum for the next season, complicating management efforts.

Effective control strategies require an integrated approach. Recommended practices include:

• The use of certified disease-free seeds.
• Crop rotation with non-host species for at least 2-3 years.
• Deep tillage to bury infected plant residues.
• Application of foliar fungicides during peak humidity periods.
• Selection of resistant or tolerant soybean varieties.