Phoma leaf spot of sorghum

Phoma sorghina is a fungal pathogen classified within the kingdom Fungi and the division Ascomycota. It is recognized as a significant agent affecting sorghum and other cereal crops worldwide, often responsible for reducing photosynthetic efficiency through the destruction of leaf tissue.

The primary symptom of the infection is the development of necrotic spots on leaves, which typically appear as purple to brown lesions with greyish centers. As the disease progresses, these lesions contain pycnidia—fruiting bodies of the fungus—which release spores to spread the infection to healthy tissues.

The pathogen completes its life cycle by over-wintering in infested crop debris, soil, and infected seeds. During the growing season, spores are dispersed through rain splashes, wind, or mechanical movement, allowing the fungus to infect new leaves under suitable environmental conditions.

The development of Phoma sorghina is heavily influenced by high humidity and moderate temperatures. Constant wet weather acts as the primary driver for rapid spread, while physiological stress in the crop can make it more susceptible to initial colonization and damage.

The impact of this disease includes significant yield losses, poor grain quality, and reduced fodder value. Effective management requires an integrated approach that focuses on reducing the inoculum density in the field and enhancing the plant's natural resistance through proper agronomic practices.

• Selection of resistant or tolerant sorghum cultivars.
• Crop rotation with non-host plants to reduce soil-borne inoculum.
• Seed treatment with systemic fungicides before planting.
• Deep tillage to bury infected plant residues.
• Maintaining optimal crop density to improve air circulation within the field.