April 14, 2025 by Zac

What is Pasture Dieback: How to Identify and Manage

Pasture dieback is a condition that affects summer-growing (C4) perennial grasses. It begins in small patches and often spreads rapidly, particularly after rainfall. The main cause is the pasture mealybug (Heliococcus summervillei), an insect that feeds on the sap of grass plants and causes significant damage during active growing periods.

Pasture dieback is a growing threat to Australian livestock producers, particularly those reliant on summer-growing tropical and sub-tropical grasses. Since re-emerging in Central Queensland in 2014/15, this complex condition has spread rapidly throughout eastern Australia — from Far North Queensland to the North Coast of New South Wales — severely reducing pasture productivity across affected properties.

This blog will help you understand what pasture dieback is, how to identify it, and how to take control of affected paddocks. We’ll also link you to our Pasture Picker Tool to help you choose dieback-tolerant grasses and legumes suited to your area.

Identifying Pasture Dieback

Diagnosing pasture dieback accurately is essential, especially as symptoms can resemble frost damage, herbicide exposure or nutrient deficiencies. If you’re seeing patchy, underperforming pasture—even after rainfall—here are the key signs to look for:

Stages of Pasture Dieback:

1. Leaf Discolouration – Yellow, red or purple colouring starting from leaf tips.

2. Stunted Growth – Plants stop growing, have fewer tillers, and roots become shallow.

3. Plant Death – Affected patches expand rapidly, especially during warm, wet conditions.

4. Weed Invasion – Bare ground is often colonised by broadleaf weeds or legumes.

Need help identifying pasture dieback in the paddock? Refer to MLA’s diagnostic guide or speak with your local agronomist.

Contributing Factors

Understanding what causes and worsens pasture dieback can help you put effective control strategies in place.

🚨 Conditions That Promote Pasture Dieback:

• Presence of pasture mealybug – The key biological trigger. These sap-sucking insects are often found near the base or roots of grass plants, especially after rain.

• High biomass – Thick pastures create microclimates ideal for mealybug activity.

• Susceptible grass species – Buffel, paspalum, kikuyu, and creeping bluegrass are among the worst affected.

• Warm, humid weather – Perfect for mealybug growth and spread.

• Active growth phase – Grasses are more vulnerable when they are vigorously growing.

🛑 Conditions That May Suppress Dieback:

• Cooler or drier weather

• Presence of legumes

• Use of less susceptible grass cultivars

• Good grazing management to reduce biomass

• Beneficial insects such as lacewings and mealybug ladybirds

Managing Pasture Dieback

There’s no single fix for dieback. Instead, a mix of strategies tailored to your landscape, soil, and pasture species is best. Here are some proven approaches for controlling pasture dieback:

🔄 Manage for Recovery

• Reduce stocking rates to reduce pasture stress

• Control weeds in bare patches to reduce competition for emerging seedlings

🌱 Reseed With Tolerant Species

• Use our Pasture Picker Tool to choose dieback-tolerant grasses and legumes suited to your region

• Include legumes to improve soil health and resilience

🚜 For Arable Land

• Cultivate affected areas and sow break crops like forage oats

• In some cases, pesticide applications may help reduce mealybug numbers, though success varies

🔥 Fire as a Tool

• Controlled burning may reduce surface mealybug populations, especially when timed correctly

Biological Control: The Role of Beneficial Insects 🐞

Natural predators are a valuable ally in the fight against pasture dieback. Encouraging these species can help reduce mealybug populations and slow the spread of damage.

• Mealybug Ladybird (Cryptolaemus montrouzieri) – both adults and larvae feed on mealybugs

• Chalcid Wasp (Callipteroma sexguttata) – a parasite of the pasture mealybug

• Generalist predators – such as lacewings and three-banded ladybirds

To promote these beneficial insects, minimise the use of broad-spectrum insecticides and maintain habitat diversity where possible.

Biosecurity and Reporting

Preventing further spread of pasture dieback starts with strong biosecurity:

• Come clean, go clean – Ensure machinery, vehicles, and livestock don’t transfer pests between properties

• Keep new pastures under surveillance for symptoms of dieback

Start Rebuilding Today

Now that you understand what pasture dieback is and how to identify it, take steps to recover and rebuild with confidence.

✅ Use our Pasture Picker Tool to select pasture varieties with improved resilience

✅ Monitor closely for pasture mealybug

✅ Implement sound grazing and weed control strategies

✅ Don’t wait—get local agronomic advice if dieback is suspected

References

1. Baker, S.J., Buck, S.R., Jennings, N.R., Hopkins, K.C., & Boschma, S.P. (2024). Pasture Dieback Identification Guide – Second Edition, NSW DPI & DAF Queensland.

2. Queensland Department of Agriculture and Fisheries. (2024). Management of Pasture Dieback Brochure. Queensland Pasture Resilience Program.

3. Diplock, N. et al. (2024). Pasture Dieback: A Management Guide for Producers and Agronomists. Meat & Livestock Australia and National Landcare Program.