Bermuda grass smut

The fungus Ustilago cynodontis is the specific causative agent of Bermuda grass smut. As an obligate parasite, it colonizes the host plant, growing systemically within the tissues. This fungus is specifically adapted to the genus Cynodon, establishing a long-term parasitic relationship that interferes with the plant's normal development and reproduction.

The primary host for this pathogen is Bermuda grass (Cynodon dactylon), which is widely used as a forage crop and a staple for turfgrass in warm climates. While it does not generally affect other crop species, its impact on the structural integrity and aesthetic value of Bermuda grass lawns and pastures can be significant in endemic regions.

Symptoms are most easily observed during the flowering stage, where the fungus induces the formation of sori, replacing the healthy inflorescences with a dark, dusty mass of teliospores. These spore-filled structures are initially covered by a delicate membrane that eventually ruptures, releasing the spores to be disseminated by wind and mechanical equipment.

The development of the disease is highly dependent on environmental conditions, particularly high humidity and warm temperatures, which facilitate spore germination and infection of the host. The pathogen can persist in the soil or be carried on the seed, ensuring that once a site is infested, the disease can re-emerge in subsequent growing seasons.

The management of Bermuda grass smut focuses on minimizing the dispersal of spores and maintaining the health of the host plants. Practical control measures include

• avoiding the use of infected seed lots;
• frequent mowing of infested areas to remove flowering heads before spore release;
• improving drainage to reduce micro-climate humidity;
• application of systemic fungicides in severe infestation cases.