Bacterial leaf stripe of sorghum

Robbsia andropogonis is a phytopathogenic bacterium responsible for the disease known as bacterial leaf stripe or bacterial wilt of sorghum. Previously classified within the Pseudomonas genus, this pathogen is now recognized as a distinct taxonomic entity. It is a Gram-negative bacterium that primarily colonizes the leaf tissues and vascular system of host plants, leading to localized necrosis and systemic weakness.

The disease primarily affects various species of sorghum, including grain sorghum, sweet sorghum, and sudangrass. Additionally, the pathogen has been identified on other hosts such as maize and certain legumes like clover. It poses a significant threat to agricultural productivity in regions where warm and humid climatic conditions favor bacterial multiplication during the growing season.

Symptoms initially appear as small, water-soaked spots on the leaves. As the infection progresses, these spots expand into elongated, reddish-brown or purple streaks, which are often limited by leaf veins. In conditions of high humidity, a bacterial ooze may be visible on the surface of the lesions. Severe infections lead to the yellowing, drying, and premature death of the affected leaves, reducing the plant's photosynthetic capacity.

The development of the disease is highly dependent on environmental factors, particularly rainfall and temperature. The bacterium is disseminated by splashing rain, wind-blown droplets, and contaminated agricultural tools. It survives between growing seasons in infected plant debris, soil, and internally or externally on infested seeds, which are critical pathways for long-distance transmission.

The economic impact of this disease includes significant yield losses and reduced fodder quality. Effective management strategies focus on preventing the establishment of the pathogen. Key practices include the use of resistant hybrids, crop rotation to minimize inoculum buildup, deep plowing to bury infected crop residues, and the use of pathogen-free seeds treated with appropriate bactericides.

• Planting certified, pathogen-tested seeds.
• Implementing strict crop rotation intervals (minimum 2–3 years).
• Removing volunteer sorghum plants from surrounding areas.
• Maintaining optimal field drainage to reduce humidity levels.