Fungi: Friend or Foe?

From a golf course perspective, you need to distinguish between fungi that are pathogenic to plants and those that are not.

The fear of fungi: fairy rings on golf courses

Fairy rings on golf courses are distinct patterns that appear on turf, characterized by circles or arcs of mushrooms, lush green grass, or sometimes dead or discoloured turf. These rings are caused by specific fungi known as basidiomycetes.

Here’s how they manifest and affect the golf course turf. One of the most visible signs of fairy rings is the appearance of mushrooms arranged in a circular pattern. These mushrooms emerge as the fungal network beneath the soil reaches a certain stage in its lifecycle. Some fairy rings cause the grass within the ring to grow more vigorously and appear greener. This is often due to the breakdown of organic matter by the fungi, releasing nitrogen and other nutrients which the grass then utilises.

In some cases, fairy rings lead to areas of dead or discoloured grass. This happens because the fungi can make the soil hydrophobic, meaning it repels water, which in turn stresses the grass by limiting its access to water and nutrients. For golf course superintendents, fairy rings present an aesthetic challenge as they can disrupt the uniform appearance of the turf, which is vital for both visual appeal and playability. Managing fairy rings involves a combination of practices, such as adjusting irrigation to compensate for hydrophobic soil, applying fungicides, and potentially modifying the soil to improve water retention and nutrient availability. Given their complex nature, fairy rings require ongoing attention and a tailored management approach, as what works on one golf course might not be effective on another due to differences in soil composition, climate and fungal species involved.

Fairy rings illustrate the intricate and often unseen ecological dynamics at work beneath the soil surface. These fungi engage in complex interactions with various soil organisms, such as bacteria, other fungi and plant roots, as well as abiotic factors like moisture levels and soil composition.

This interaction network influences not only the localised environment where the fairy ring occurs but extends its impact on the broader ecosystem. As these fungi break down organic matter and alter soil chemistry, they can affect nutrient cycling and soil health, demonstrating their ecological significance. The identification of over sixty fungal species associated with fairy rings highlights the vast ecological variety present, presenting a formidable challenge for turf managers attempting to develop effective control strategies.

Turf Management Challenges

Fairy rings underscore particular challenges and considerations essential in modern turf management:

Adaptability: Fairy rings compel turf managers to adopt a flexible mindset, requiring them to explore and evaluate a range of management strategies. Since fairy rings vary significantly in appearance and their response to treatments, an approach effective in one scenario might fail in another. This necessitates an adaptive management style where turf professionals continuously refine their methods based on observation and feedback, ensuring they tailor solutions to specific conditions.

Innovation: Continuous innovation lies at the heart of managing such complex issues. The development of new fungicidal treatments, soil surfactants, and solutions aimed at enhancing soil nutrition displays a broader movement towards adopting science-driven and technologically advanced approaches. These innovations are critical in developing management techniques that are not only effective but also environmentally sensitive.

Sustainability: With sustainability receiving increasing emphasis, turf managers are encouraged to employ practices that minimize negative environmental impacts. This implies reducing reliance on chemical solutions, promoting biodiversity within the soil ecosystem by encouraging beneficial organisms, and implementing cultural practices that synergize with natural processes. Sustainable practices help maintain soil health and ecosystem balance, reducing the likelihood of problematic outbreaks like fairy rings.

Fungal Ecology and Biology

In-depth exploration of the biology and ecological functions of fairy ring fungi can reveal critical insights into their life cycles, interactions, and impacts on soil health. This knowledge is pivotal for developing management strategies that mitigate harm to the surrounding ecosystem, ensuring that solutions are both targeted and sustainable.

Integrated Management

A holistic approach that combines cultural practices, chemical treatments, and biological controls may offer more robust and environmentally friendly management solutions. By integrating multiple control methods, turf managers can address the issue from various angles, increasing effectiveness and reducing the risk of adverse ecological consequences.

Predictive Tools

Development of predictive tools capable of forecasting fairy ring appearances based on environmental indicators such as climate conditions, soil health metrics, and historical data could enable initiative-taking management. By anticipating when and where fairy rings are likely to occur, turf managers can implement timely interventions, potentially preventing severe infestations before they arise.

Beyond their immediate impact, fairy rings symbolize larger environmental challenges, reflecting the delicate interplay between human-managed systems and natural ecosystems. They serve as a potent reminder of the need for sustainable and mindful management practices that respect the intricate balances within natural environments. As turf managers navigate these challenges, their insights contribute to broader environmental stewardship efforts, promoting a harmonious coexistence with nature.

Conclusion

Fairy rings on golf courses represent a complex and multifaceted challenge that manifests not only in visible patterns of mushrooms and turf health variations but also in intricate ecological interactions beneath the surface. These rings underscore the necessity for golf course superintendents to adopt adaptable, innovative, and sustainable management practices.

Given their variability and impact, fairy rings demand a tailored approach that incorporates continuous research and a deep understanding of soil and fungal biology. By integrating diverse management strategies and predictive tools, turf managers can more effectively anticipate and mitigate the effects of fairy rings, while also contributing to a broader understanding of ecological stewardship.  The management of fairy rings exemplifies the intricate balance required between artificial landscape maintenance and natural ecosystem processes, highlighting the importance of harmonizing these often-competing interests through mindful and informed practices.

Dr John Dempsey - Turfgrass Pathologist

The importance of Fungi

Without fungus, your grasses wouldn’t grow very well, and we would be in a whole heap of trouble - there I’ve said it.

Here’s how grassland fungi work. Grass has the green pigment chlorophyll in its leaves and can therefore create organic molecules using photosynthesis. Fungi cannot - what it can do is to break down complex organic molecules to the grass in return for some photosynthesis sugar which the grass has. Grass cannot break down complex organic molecules, but fungi can… are you still with me? This shared relationship is called mycorrhizal, a mutual relationship between a plant and some fungi. If we kill off the fungi, we will most likely reduce the grass plant’s survival rate during periods of pressure.

Next time you are digging a bunker face out, or stripping turf from the rough, take a look at the fine mushroom smelling white strands which work their way through the soil - this is the actual fungi, or hyphae and this attaches to the roots in the rhizosphere of the grass - this is when the beneficial relationship begins. The mushrooms you see are merely the fruiting part of the fungus that grows when environmental conditions are suitable (usually autumn and spring).

James Hutchinson Freelance Ecologist.

The disease triangle

It is necessary for all three factors; the pathogen, the host and the environment to be present in the same place at the same time before disease occurs.

Time could be introduced as a fourth factor;

• The time that the host plant is most susceptible to disease development
• The time that the environmental conditions are conducive to disease development
• Length of time between inoculation with pathogen and appearance of disease symptoms

What is a pathogen?

A pathogen is an organism that causes disease in animals or plants

What is a fungus?

Fungi are a separate biological kingdom from plants, animals, and bacteria, and they include well-known organisms such as moulds, yeasts, and mushrooms. The grassland fungi live below ground, forming intricate networks of fine threads known as mycelia; only the fruiting body, the spore-producing “mushroom” or “fungus”, is visible above ground at certain times of the year. To add to the mystery, the fungus does not always produce fruiting bodies each year, so identifying fungi can be difficult.

Fungi strategies

The strategy that fungi use to obtain nutrients determines which it is. A few types:

• Saprotrophic fungi obtain nutrients from decaying organic matter and are not pathogenic (though they can become so)
• Biotrophic fungi obtain nutrients from living cells and are pathogenic
• Necrotrophic fungi obtain nutrients from dying cells and are pathogenic

All fungi will have mushrooms as they are simply one of the ways that fungi reproduce; they can do so both sexually (mushrooms) and asexually (hyphae - a type of fungal root) break off and get spread elsewhere.

There are many distinct types of fungi (estimated 15,000 species in the UK). Due to the range of habitats that are found on a golf course they can support a wide range of fungal species. In some instances hundreds of species have been identified on a single course.

Two groups of fungi affect turf:

• Ascomycota - Includes: Anthracnose. Dollar Spot, Microdochium, Leaf Spot, Take-all patch
• Basidiomycota - Includes: Brown Patch, Fairy rings, Red Thread, Rust

Dr Abigail Graceson  - Technical Manager, Agrovista UK Ltd