Microdochium patch in turf

This article aims to help you minimise the risk of turf damage by providing an overview of the biology of the disease, how to identify an attack and how to begin formulating an effective management strategy.

The Significance of Microdochium patch

Microdochium patch is an extremely common turf disease that can affect all types of turfgrasses.

Although typically considered a late summer, autumn, and winter disease, it can occur at any time of the year, primarily driven by environmental conditions.

Cool, wet periods, even during the summer, can lead to outbreaks of this disease, making it a year-round concern for turf managers.

Biology and pathology

Microdochium nivale is a highly adaptable fungus that can live in the thatch and dead organic matter at the turf base without immediately causing disease.

This ability allows the fungus to survive and then proliferate by producing a large number of spores when conditions become favourable. These spore would then be available to infect new turf and continue the cycle of reproduction.

Unlike many other fungi that cause turf diseases, Microdochium nivale is capable of actively growing in cool conditions.

This characteristic allows it to develop and spread rapidly throughout the year in the UK and Ireland where conditions are generally favourable.

Identification of Microdochium patch

Early identification of Microdochium patch is crucial for effective management and control. The disease typically appears as small, circular patches of discoloured turf, often dark brown and water-soaked.

These patches expand quickly under wet conditions, forming distinct circular patterns. The centre of the patches turns tan, while the outer edges remain a dark gravy brown colour.

To confirm the presence of active Microdochium nivale, turf managers can take a core sample from their turf and place it in a sealed plastic bag overnight to accelerate its development.

If the fungus is active, mycelium will be visible on the turf the following morning. This method, combined with monitoring local environmental conditions, helps with early disease detection and management.

Because the disease is so pervasive, management strategies generally assume its presence and focus on monitoring for the conditions that favour its development. Damp and cool/mild conditions should trigger preventative measures well before any symptoms become visible.

Conditions favouring disease development

The primary driver for Microdochium patch development is extended periods of leaf wetness. This might result from irrigation, rainfall, dew formation, guttation or high relative humidity and be accentuated by poor airflow.

Turf health also plays a significant role and so low light levels or shading would increase the risk of attack. Turf nutrition is important (nitrogen mainly and potassium levels) and so it is important to avoid using unduly excessive or restrictive fertiliser inputs.

The disease thrives in organic matter and so the presence of thatch will increase the risk of this disease.

Practical management of Microdochium patch

Early Detection

Environmental monitoring tools can provide valuable insights into disease pressure based on local conditions, helping turf managers anticipate and prepare for potential outbreaks.

The Syngenta Turf Advisor app contains a number of helpful metrics to help you monitor the risk of attack.

Early detection is key to managing Microdochium patch to prevent the turf becoming unduly scarred. Turf managers should always monitor for general discolouration in the turf and maybe use the core incubation technique to detect early fungal activity.

Integrated Turf Management Strategies

Effective Integrated Turf Management (ITM) strategies for Microdochium patch include:

• Minimising leaf wetness: Leaf wetness can be minimised with physical removal of surface moisture/dew where appropriate or the use of surfactant-based dew dispersants
• Optimising Irrigation Practices: Minimising periods of leaf wetness by adjusting irrigation schedules.
• Maintaining Optimal Nutrient Levels: Ensuring adequate growth with the appropriate use of nitrogen and supporting nutrition levels (iron and potassium) to maintain turf resilience and help harden the sward against attack. Avoid using organic or nitrate sources of nitrogen during periods of high disease risk.
• Fungicide applications: Modern fungicides can be extremely effective management tools against Microdochium patch disease. Generally, they work best when applied preventatively but they can also offer curative control of active outbreaks. Fungicide programmes need to be scheduled properly to be fully effective during extended periods of high disease pressure. The choice of fungicide, sequencing and frequency of applications will be dependent on conditions and may require specialist advice.
• Managing Thatch and Organic Matter: Maintain subsurface organic matter contents with recommended guidelines to maintain a healthy and functioning soil profile and help reduce the saprophytic habitat of the fungus.

Conclusion

Understanding the biology and environmental conditions that favour Microdochium patch is essential for effective turf management in the UK and Ireland.

Early detection, combined with integrated turf management practices, can significantly reduce the impact of this pervasive disease.

By using monitoring technology, maintaining optimal nutrient levels, minimising leaf wetness, managing thatch and deploying the use of modern fungicides when needed, turf managers can effectively manage Microdochium patch and maintain turf performance throughout the year.