Eremochloa anthracnose

Early symptoms include small, irregular, water-soaked lesions on leaf blades. Over time, these spots turn yellow, then tan or straw-colored as the tissue dies.

A key diagnostic feature is the appearance of dark, hair-like structures (setae) and small black dots (acervuli) on the surface of the infected lesions, visible under magnification.

As the disease progresses, the lawn appears thin and patchy. In severe cases, the entire plant may wilt and die because the fungus also attacks the root system, causing root rot.

The turf may lose its vibrant green color and develop a blighted appearance. These patches often expand during periods of high humidity and heat.

In the early morning, especially under dew-covered conditions, a faint fungal growth may be visible on the leaves, indicating active sporulation.

The disease is caused by the pathogenic fungus Colletotrichum eremochloae. It is a specialized pathogen that primarily targets centipede grass (Eremochloa) and other related turfgrass species.

The fungus produces spores known as conidia within specialized structures called acervuli. These spores are disseminated primarily through water splashes during rainfall or irrigation, as well as by wind currents.

The pathogen survives the dormant season in infected plant debris, thatch, or soil. It can remain viable for extended periods, waiting for the right environmental triggers to resume activity.

Once it colonizes the host plant, the fungus grows intercellularly, secreting enzymes that break down plant cell walls and absorb nutrients, leading to tissue degradation.

Understanding the biology of Colletotrichum eremochloae is essential for professionals, as the fungus is capable of rapid mutation and adaptation to various environmental conditions.

Anthracnose development is strongly favored by prolonged periods of high humidity and rainfall, which keep the leaf surfaces wet for extended hours.

Temperatures between 25°C and 30°C (77°F to 86°F) are optimal for the growth and spread of Colletotrichum eremochloae, making summer the peak risk period.

Stressed turfgrass, particularly that suffering from drought, compacted soil, or nutrient imbalances (especially low potassium), is significantly more susceptible to infection.

Poor airflow caused by dense vegetation or obstructions around the lawn prevents leaf surfaces from drying quickly, facilitating the infection process.

Mechanical damage to the grass blades from dull mower blades or heavy foot traffic creates entry points for the fungus, accelerating the spread of the disease across the lawn.

Eremochloa anthracnose is a destructive disease that can quickly devastate the aesthetics of high-quality lawns, golf courses, and residential turf.

The damage often results in permanent thinning of the turf density, which reduces the lawn's ability to suppress weeds and leads to further degradation.

Root system impairment caused by the fungus prevents plants from effectively absorbing water and essential nutrients, leading to long-term decline.

The economic impact is significant due to the costs associated with fungicide applications, topdressing, and potential total renovation of severely affected lawn areas.

If left unmanaged, the disease can become endemic to the site, requiring continuous and expensive maintenance inputs to suppress the pathogen population.

The primary control strategy involves good cultural practices: ensure proper soil drainage and avoid excessive, shallow watering that promotes surface wetness.

Aerification is crucial to reduce soil compaction and improve oxygenation, which strengthens the grass's natural defenses against fungal stress.

Maintain balanced fertilization: focus on sufficient potassium levels and avoid excessive nitrogen in summer, which encourages succulent, susceptible leaf growth.

• Mow at the correct height to maintain turf vigor
• Remove excess thatch to reduce the survival site for the pathogen
• Use fungicides as a curative or preventative measure when weather conditions favor outbreaks
• Sanitize lawn equipment to prevent cross-contamination between areas