Sorghum anthracnose

Sorghum anthracnose is a destructive disease caused by the fungus Colletotrichum sublineola. This pathogen is globally recognized as one of the most significant threats to sorghum production, capable of causing devastating epidemics. The fungus is known for its high genetic variability, allowing it to adapt to different environmental conditions and bypass some plant resistance mechanisms.

The primary host for this fungus is sorghum (Sorghum bicolor), including grain, forage, and sweet sorghum varieties. Additionally, it can infect several wild grass species, which serve as alternative hosts. The pathogen persists primarily through infected crop residues left on the field surface and, to a lesser extent, via contaminated seeds used in planting.

Symptoms are highly diverse and may appear as small circular or irregular spots on leaves. These lesions often show a distinct red, purple, or dark brown margin. As the disease progresses, the centers of the lesions develop small, black, spine-like structures called acervuli. Severe infections lead to leaf blight, stalk rot, and grain mold, which significantly stunt the growth and overall development of the plant.

The development of Colletotrichum sublineola is highly dependent on humidity and temperature. Warm temperatures (typically between 25°C and 30°C) combined with high rainfall or heavy dew are conducive to rapid spore production and dispersal. Splashing rain facilitates the movement of spores from the soil or infected debris to the lower leaves, eventually spreading throughout the entire canopy.

• Planting certified, disease-free seed lots.
• Implementing crop rotation with non-host species.
• Deep plowing to bury infected crop residues.
• Application of foliar fungicides at the onset of symptoms.
• Selection and use of resistant or tolerant sorghum hybrids.

The economic impact of sorghum anthracnose is substantial, as it leads to both quantitative and qualitative losses. Infected plants exhibit reduced photosynthetic capacity, resulting in lower grain filling and lighter test weights. In severe cases, stalk infection weakens the plant structure, leading to lodging, which complicates harvesting and further increases yield losses for farmers.