Glomerella glycines

Glomerella glycines is an ascomycete fungus that serves as the teleomorph (sexual stage) of the pathogen responsible for soybean anthracnose. In agronomic practice, the fungus is frequently identified by its anamorph, Colletotrichum truncatum. It is classified within the Sordariomycetes class and remains a significant biotic stressor for soybean crops globally.

The primary symptom of the disease is the development of brown or black sunken lesions on the stems, leaves, and pods of infected soybean plants. These lesions often contain small, dark, hair-like structures known as setae. Severe infestations lead to premature senescence, reduced seed weight, poor germination quality, and significant yield losses in both seed quantity and oil content.

The life cycle of this pathogen involves both asexual and sexual reproduction. The fungus survives primarily in infested crop debris, soil, and infected seeds. During the growing season, conidia are dispersed by rain splash, wind, or contaminated equipment. The infection typically initiates on the lower canopy and spreads upwards, intensifying as the plant reaches the reproductive growth stages.

Conditions favoring the spread and severity of Glomerella glycines include warm temperatures (ranging from 20°C to 30°C) and prolonged periods of high humidity or rainfall. High planting density creates a humid microclimate within the canopy, which is conducive to rapid fungal sporulation and colonization, making dense fields more susceptible to severe outbreaks.

Management strategies for controlling this pathogen emphasize a holistic approach. Key practices include using certified, disease-free seed, implementing a crop rotation system that avoids legumes for at least three years, and proper tillage to bury infected stubble. Furthermore, seed treatments with systemic fungicides are highly recommended, supplemented by timely foliar fungicide applications if environmental conditions remain favorable for disease development.