Pink patch

Limonomyces roseipellis is a basidiomycetous fungus responsible for a turfgrass disease commonly referred to as pink patch. This pathogen primarily targets cool-season grasses, causing aesthetic degradation and, in severe cases, loss of turf density. The disease is known for the distinctive pinkish mycelium that develops on the leaf blades during periods of high humidity.

The primary hosts for this pathogen include fine fescues and Kentucky bluegrass. While it can occur on various turf types, lawns with poor air circulation and dense canopy cover are particularly susceptible. The fungus typically remains active within the leaf tissue and the thatch layer, making it a persistent issue if left unmanaged.

Symptoms are identified by the appearance of irregularly shaped, circular or diffuse patches of infected grass. These spots may initially look water-soaked before turning tan or straw-colored. During wet, overcast conditions, a characteristic salmon-pink or reddish mycelial growth can be observed on the grass blades, which helps differentiate it from other patch-type diseases.

Environmental conditions are the main drivers of pink patch development. The pathogen thrives in cool to moderate temperatures ranging from 10°C to 20°C and requires extended periods of leaf wetness. High humidity and poor drainage create the perfect environment for the fungus to spread through the turf canopy via wind-blown spores and contaminated clippings.

Management focuses on improving environmental conditions and utilizing chemical control when necessary. Key strategies include:

• Reducing leaf wetness through early morning mowing or surface drainage improvements.
• Avoiding excessive nitrogen fertilization which encourages lush, succulent growth susceptible to fungi.
• Applying systemic fungicides recommended for basidiomycetes during the peak disease season.
• Removing clippings from infected areas to reduce the pathogen load on the lawn.

Integrated pest management remains the most effective approach for controlling pink patch. By combining good cultural practices, such as proper irrigation scheduling and thatch management, with targeted fungicide applications, turf managers can minimize the impact of Limonomyces roseipellis and maintain healthy, resilient grass cover.