Paspalum smut

Ustilago schroeteriana is a highly specialized fungal pathogen belonging to the Ustilaginaceae family, which causes a disease known as paspalum smut. This pathogen predominantly affects various species within the Paspalum genus, which are essential forage and turf grasses in many temperate and tropical regions.

The disease is characterized by the formation of large, swollen galls or pustules in place of the normal spikelets or inflorescences. These galls contain a dense mass of black, dusty teliospores. As the disease progresses, the protective membrane of the gall ruptures, facilitating the dispersal of spores by wind, rain, and mechanical contact.

The development and spread of the fungus are heavily dependent on environmental conditions, particularly high humidity and moderate temperatures during the host's flowering stage. The spores of the fungus can survive in the soil or on infected plant debris, creating a persistent inoculum source that challenges subsequent growing seasons.

The economic impact of paspalum smut is primarily observed in the significant reduction or total loss of seed yield. Because the fungal structures replace the grain-bearing parts of the plant, the plant's reproductive efficiency is severely impaired. In addition to yield loss, severe outbreaks can impact the quality of forage, posing potential issues for livestock grazing.

Management and prevention focus on integrated approaches. Key strategies include:

• Sourcing clean, pathogen-free seed stocks.
• Implementing crop rotation to reduce soil-borne inoculum.
• Mowing infected areas before gall rupture to minimize spore dispersal.
• Applying systemic fungicides where economically feasible to protect vulnerable stands.

Maintaining field hygiene by clearing crop residues and monitoring for early symptoms are critical for preventing the establishment and further spread of Ustilago schroeteriana in specialized grass-growing areas.