How to Treat Pythium Root Rot in Your Lawn

Pythium Root Rot is a fungal disease that affects both warm- and cool-season grasses. It thrives in warm, humid conditions, particularly during the Australian spring and summer when increased rainfall or excessive lawn watering creates an ideal environment for fungal growth.

Pythium can target either the leaves (Pythium Blight) or the roots (Pythium Root Rot). While cultural practices such as reducing thatch, improving aeration, and adjusting watering schedules can help minimize disease stress, the most effective way to control Pythium Root Rot is by applying an appropriate fungicide.

Table of Contents

• What is Pythium Root Rot?

• What Causes Pythium Root Rot?

• Pythium Blight vs. Pythium Root Rot: What’s the Difference?

• How to Get Rid of Pythium Root Rot

What is Pythium Root Rot?

Pythium Root Rot is caused by various Pythium pathogens and primarily affects stressed or waterlogged lawns. This fast-spreading disease can destroy a lawn within days, making early detection and quick action crucial. Preventative treatments can also be beneficial when weather conditions favor an outbreak.

Symptoms of Pythium Root Rot

Pythium Root Rot first appears as small, discolored circular patches (2–5 cm in diameter, sometimes up to 15 cm). Affected grass may feel slimy to the touch. As the disease progresses, the patches darken to brown, indicating more severe damage.

What Causes Pythium Root Rot?

Pythium thrives in overly wet lawns and humid conditions, making recently renovated lawns that receive excessive watering especially vulnerable. It’s also common in regions experiencing:

• High summer rainfall

• Extreme heat with overwatering as a response

• Waterlogged or compacted soils with poor drainage

Because Pythium exists in all soil types, lawns with standing water or excessive moisture are at a higher risk of infection.

Which Turf Types Are Prone to Pythium Root Rot?

Pythium Root Rot affects both warm- and cool-season grasses, including:

• Warm-season: Couch/Bermuda Grass, Buffalo, Kikuyu, and Zoysia

• Cool-season: Ryegrass, Kentucky Bluegrass, Fescue, and Bentgrass

Pythium Blight vs. Pythium Root Rot: What’s the Difference?

While both diseases stem from Pythium fungi, they differ in their impact and environmental triggers.

• Pythium Blight affects leaves, leaving them greasy or covered in white, web-like patches, especially in the morning. It causes discoloration and can kill the leaf tissue.

• Pythium Root Rot is more severe, attacking the roots in waterlogged soils, leading to rapid turf decline. It is often linked to heavy rainfall, poor drainage, or over-irrigation.

How to Get Rid of Pythium Root Rot

Although Pythium Root Rot can be highly damaging, you can take steps to prevent and control it through proper lawn care practices and fungicide application.

Prevention and Control

1. Improve Drainage and Aeration

• Aerate your lawn annually to reduce soil compaction and improve air and water movement.

• Address drainage issues to prevent standing water around the root zone.

2. Manage Watering Carefully

• Water deeply but infrequently to promote deep root growth.

• Water early in the morning to ensure the lawn dries throughout the day.

3. Monitor Thatch Levels

• Excess thatch retains moisture and creates an ideal environment for fungi.

• Dethatch regularly through vertimowing, scarifying, or grooming.

4. Use Proper Nutrient Management

• Avoid overusing nitrogen fertilizers, which encourage weak, lush growth that is more disease-prone.

• Apply a balanced fertilizer to maintain resilient, healthy turf.

Treatment Methods

Currently, few fungicides are registered for home use against Pythium Root Rot. One of the most effective options is Impala, which should be applied at a rate of 60mL per 100m² of lawn, following the label instructions and using appropriate protective gear.

Pythium Root Rot can spread quickly during wet Australian summers or in areas experiencing above-average rainfall. However, with proper lawn care practices and effective fungicides, you can prevent and control this destructive disease. Visit our online store to explore a range of fungicides for your lawn care needs.

Uncertain still ? Call professionals at All Year Round Turf 1300 887 348