What is Fusarium Patch Disease?
Fusarium patch, often referred to as snow mould, is a turf disease that typically appears in autumn and during milder spells in winter. It’s one of the more challenging lawn diseases to manage, and while it’s most commonly associated with the colder months, it can develop at any point in the year if the conditions are right.
It often becomes particularly visible after periods of melting snow, which is where the nickname “snow mould” comes from. The disease is known for creating brown or yellowing patches across a lawn, gradually increasing in size if left untreated.
The Latin name of the fungus that causes the disease symptoms is Microdochium nivale but in the past its Latin name was Fusarium nivale, hence its common name.
What does Fusarium look like?
Fusarium looks like an irregularly shaped orange-brown area on the turf usually a few centimetres in diameter, sometimes with a white or pink fluffy fungal growth around the edge of the patch.
These patches often begin as small yellowish areas before turning brown and expanding. During periods of sustained moisture, a cottony white or pinkish layer may appear around the margins, a sign of active fungal growth. This should not be confused with other turf issues such as red thread, as Fusarium tends to create a softer, matted appearance.
Over a period of weeks these patches die back and can create areas of bare ground, which gradually recover naturally if weather and soil conditions are warm enough. However, if the disease occurs in the autumn, the conditions may not be suitable for recovery until the following spring, as grass growth slows and the turf cannot repair itself as quickly.
The disease can occur throughout the year, but is most damaging in autumn and winter because the turf is not growing fast enough to recover. Snow can worsen symptoms, allowing the fungus to spread beneath the insulating layer and cause more extensive damage. Most lawns will make a full recovery once the grass begins actively growing again.
Why has it affected my turf?
As with all plant diseases, the spores of this disease are abundant everywhere, but only produce symptoms if environmental conditions are right for their growth.
Fusarium becomes active in mild, humid, and still conditions, particularly when the grass remains wet for long periods. Factors such as reduced daylight, persistent cloud cover, lingering morning mist, limited airflow and overnight temperatures that remain above seasonal averages all contribute to an environment the fungus favours.
Freshly laid turf can appear more susceptible because it has been mown short prior to harvesting and is under natural stress while establishing in its new location. Although Fusarium can develop on any lawn, short sward’s show symptoms more visibly which is why golf greens maintained under 7mm often monitor it closely.
When is Fusarium likely to appear?
Whenever the weather is very still and humid and the grass stays wet for most of the day, Fusarium patches are likely to develop.
Fusarium is rarely a problem in the summer but is very common at other times of the year under these conditions. The fungus grows in the thin film of water that forms on the grass leaf, meaning heavy dews, slow-clearing moisture and stagnant air all encourage its spread.
Shorter daylight hours, cloudy weather and mild overnight temperatures can intensify outbreaks, and after snowfall the disease can quickly worsen as snow shields the fungus from colder air. These factors together explain why Fusarium becomes particularly active in autumn and winter.
HOW CAN I AVOID IT DEVELOPING IN MY LAWN?
Avoid over-feeding. Avoid damp, shady locations with still stagnant air for laying turf. In order to keep the lawn surface dry, mow regularly to prevent the leaves of the grass becoming too long. Air movement dries the lawn surface, making conditions less suitable for growth of fungal diseases.
The condition of the soil under the turf is very important in defending against disease attack. A well-structured, free-draining soil will help produce healthy turf and reduce the likelihood of persistent moisture sitting at the surface.
Improving aeration and drainage through scarifying, spiking or hollow-tining helps the lawn dry more quickly after rainfall or morning dew. Increasing airflow by trimming back overhanging trees or shrubs also reduces the moisture conditions Fusarium relies on. Many turf managers remove heavy dew in the mornings using a switch or bamboo cane to reduce the length of time water stays on the leaf.
Can I control Fusarium chemically?
There are currently no fungicides recommended for use by amateur gardeners in the UK to control this disease. This means cultural management by encouraging air flow, improving drainage and supporting healthy turf growth remains the most effective approach.
SHOULD I CONTACT THE TURF GROWER ABOUT THE DISEASE ON MY TURF?
Only if the symptoms were present on delivery or develop within a couple of days afterwards.
Fusarium spores are naturally present in the environment, and symptoms often show once turf is laid into conditions that favour the fungus. Because turf is mown prior to harvesting and temporarily stressed as it establishes, any disease activity can appear more noticeable in the early days after installation.
Inturf’s approach to quality and maintenance
At Inturf, our turf is grown under a comprehensive, year-round maintenance regime designed to promote resilience, healthy growth and minimal disease pressure. Our growing and maintenance team carries out regular inspections, monitoring moisture levels, airflow, soil structure and early signs of plant stress.
We do not harvest turf showing active Fusarium. Our priority is always to supply customers with strong, healthy turf that has been carefully managed throughout the growing cycle. From aeration and drainage routines to controlled mowing heights and nutrient management, every part of our process supports high-quality turf that establishes well once laid.
This commitment to quality helps ensure that the turf you receive is robust, well-maintained and prepared for long-term performance.
SUMMARY
Lay turf in sites where air can flow over the surface of the lawn to dry it out. Do not feed any more than necessary – many lawns do not need feeding if laid on fertile soil. Follow the maintenance tips on this blog to particularly focused around maintaining air flow and monitoring moisture levels.
Originally produced for the TGA by independent agronomist Robert Laycock, member of RIPTA. Edited and developed by Inturf in 2025.
