Slime Mould

What is Slime Mould?

Slime mould is a harmless fungal-like organism that occasionally appears on turfgrass during warm, humid, and wet conditions. Despite its appearance, it does not infect or damage turf plants. Instead, it feeds on organic matter, bacteria, and microorganisms found on the turf surface.

While often alarming to turf managers and homeowners, slime mould is primarily a cosmetic issue.

Symptoms of Slime Mould

Above Ground

• Grey, white, purple, yellow, orange, or black patches on turf.
• A powdery, crust-like or foamy appearance.
• Turf may appear discoloured or flattened beneath the slime mould.
• Patches can range from a few centimetres to over a metre in diameter.

Turf Health

• Roots and crowns remain healthy.
• No plant tissue infection occurs.
• Turf usually recovers immediately once it is removed or breaks down naturally.

Conditions That Favour Slime Mould

It is most common when:

• Humidity is high.
• Turf remains wet for extended periods.
• Heavy dews are present.
• Organic matter levels are elevated.
• Airflow is limited.

Outbreaks are often seen during spring, summer, and periods of prolonged rainfall.

Management Strategies

Cultural Control

In most cases, no treatment is required.

Effective options include:

• Dragging a hose, brush, or rake across affected areas.
• Washing the mould from the leaf surface with irrigation.
• Improving airflow and sunlight penetration.
• Reducing excessive moisture where possible.

Fungicide Applications

Fungicides are generally not recommended, as slime mould does not infect the turf and typically disappears naturally within a few days.

Key Takeaway

While it may look concerning, but it is one of the least damaging turf issues encountered by turf managers. Because it does not infect or kill turfgrass, management is usually limited to physically removing the growth and improving drying conditions. They are not plant parasitic. The fruiting moulds can become that thick on the leaf that the photosynthetic ability of individual leaves is greatly reduced. When this is a problem in a worst case situation.

Expect the moulds to disappear in a few weeks when treated with professional lawn care products.

Contact Lawn Addicts for advice.