Soybean powdery mildew

Erysiphe glycines is an obligate fungal pathogen belonging to the kingdom Fungi, order Erysiphales, and genus Erysiphe. It is the causal agent of soybean powdery mildew, a significant foliar disease that occurs globally in areas where soybeans are cultivated, potentially impacting crop health during the growing season.

The characteristic symptoms of the disease appear as white, dusty, felt-like patches on the surface of leaves, stems, and sometimes petioles. As the infection progresses, these spots coalesce to cover entire leaflets with a mycelial mat. Eventually, the infected foliage turns yellow, dries out, and falls off prematurely, which severely inhibits the plant's ability to photosynthesize.

The disease cycle involves the production of conidia that are easily dispersed by wind currents to healthy plants. The fungus thrives in temperatures between 20°C and 25°C and is favored by conditions of moderate humidity or alternating wet and dry weather. The pathogen can overwinter on plant debris and potentially on alternative hosts, acting as a recurring source of infection.

The impact of Erysiphe glycines on crop productivity is significant due to the reduction in canopy health. Severe infections cause stunted plant development, reduced pod filling, and a decrease in seed size and quality. In optimal conditions for the pathogen, yield losses can become economically damaging if the disease is not managed in a timely manner.

Effective management strategies rely on a combination of cultural and chemical control measures:

• Planting resistant or tolerant soybean cultivars.
• Practicing crop rotation to break the disease cycle.
• Removing volunteer plants and managing plant debris after harvest.
• Applying preventive or curative fungicides, such as triazoles or strobilurins, during the vegetative or early reproductive stages when symptoms are observed.