Long smut of sorghum

Long smut of sorghum, caused by the fungus Sporisorium ehrenbergii, is a destructive plant disease that targets the reproductive structures of the host. This pathogen is a basidiomycete that specifically affects the inflorescences of sorghum plants. The disease is known for its ability to reduce yields by replacing grain with fungal structures, making early detection vital for crop management.

The primary host for this fungus is sorghum. The pathogen infects the developing ovaries, causing significant physiological stress and reproductive failure. In regions where sorghum is grown intensively, long smut can reach epidemic proportions if environmental conditions favor the spread of fungal spores during the flowering stage of the crop.

Symptomatology is characterized by the transformation of florets into elongated, thin sacs known as sori. These structures are initially enclosed in a greyish membrane that eventually ruptures to expose a dark, powdery mass of spores.

• Elongated, cylindrical galls replacing seeds.
• Ruptured membranes revealing black spore masses.
• Severe distortion of the sorghum panicle.

Disease development is highly dependent on environmental factors, particularly temperature and humidity. Infection typically occurs during the anthesis stage when spores are dispersed by wind and land on the stigmas of the flowers. Once the spores germinate, the fungus colonizes the ovary, eventually replacing the internal tissue with its own sporogenous hyphae.

Protection strategies primarily focus on seed treatment using effective systemic fungicides to prevent early-stage infection. Furthermore, utilizing resistant cultivars is highly recommended to minimize the impact of the disease. Proper crop rotation, field sanitation to remove infected plant debris, and controlling volunteer sorghum plants in and around fields are critical practices to maintain long-term crop health.