Head smut of millet

Pathogen and disease type. The causal agent of head smut in millet is the fungus Anthracocystis destruens (formerly classified as Sphacelotheca destruens). This pathogen belongs to the smut fungi group and causes systemic infection, transforming the floral parts of the host plant into a mass of fungal spores.

Affected crops. The disease primarily affects proso millet (Panicum miliaceum). The pathogen is host-specific, although various physiological races of the fungus exist, which may affect the susceptibility of different millet cultivars and genotypes in various geographical regions.

Symptoms and signs. Typical symptoms become visible during the heading stage. The entire panicle is replaced by a swollen, deformed structure encased in a greyish membrane. When this membrane ruptures, it releases dark, powdery teliospores, which can contaminate healthy seeds during harvest or dispersal by wind.

Development and damage. Infection occurs mainly through soil-borne or seed-borne spores. The disease development is favored by specific environmental conditions during seed germination, typically involving soil temperatures between 15°C and 25°C. The economic impact is significant, as the infection causes complete grain loss in affected panicles, potentially reducing total crop yields in high-prevalence areas.

Control and prevention. Management of head smut relies on a combination of cultural and chemical strategies:

• Use of certified, disease-free seed lots;
• Systematic chemical seed treatment using effective fungicides;
• Crop rotation to reduce spore load in the soil;
• Selection and planting of genetically resistant millet varieties.