Menu

CausesLow risk

Why Is My Lawn Dying in Patches?

Written by PestMan Editorial TeamTechnical review pendingPublished Updated

Quick answer

Brown patches can be caused by pests, but also by dry spots, poor drainage, shade, fungal disease, compacted soil or dog urine. Pests are likely if patches spread quickly in warm weather, grass blades look chewed, birds are feeding on the lawn, or turf lifts easily. A soapy-water test finds armyworm; lifting a section of turf reveals curl grubs.

Why this happens

In Queensland and northern NSW, lawn armyworm can strip warm-season grasses within days in late summer and autumn, often after rain. Curl grubs eat roots through summer and autumn, so patches brown off even when watered.

Non-pest causes are just as common. Dry patches from uneven watering or hydrophobic soil, fungal diseases in humid weather, shade, compaction, and dog urine (often with a green ring around a dead centre) all look similar at a glance.

What you may be seeing

  • Patches spreading quickly across the lawn over days (armyworm).
  • Ragged, chewed grass blades and small green-brown droppings (armyworm).
  • Turf that rolls back like carpet with C-shaped grubs beneath (curl grubs).
  • Ibis, magpies or other birds feeding intensively, or bandicoots digging.

What you can do

  • Do a soapy-water test: mix a bucket of water with a good squirt of dishwashing liquid, pour it over the edge of a patch, and watch for caterpillars within about 10 minutes.
  • Cut and lift a small square of turf at the edge of a patch and look for grubs in the top few centimetres of soil.
  • Check watering coverage, drainage and shade.
  • If pests are confirmed, use a product registered for that pest and your turf type, following the label.

What not to do

  • Do not apply insecticide before confirming a pest is present.
  • Do not mow very short to "remove" damage; it stresses the turf further.
Using pest products safely

If you use any insecticide, bait or trap, read the label first and follow it exactly. Australian law requires products to be used only as the label directs, including around food, children and pets.

When professional help may be needed

A lawn care specialist or pest manager can confirm the cause and treat large areas. For non-pest causes, a turf specialist or garden centre can advise on watering, soil and disease.

Lawn Pests

Caterpillars and beetle larvae that eat grass leaves or roots, leaving brown, dying patches. Armyworm and curl grubs cause most lawn damage in eastern Australia, especially in warm, humid months.

Species mentioned

Lawn Armyworm

Spodoptera mauritia

A moth caterpillar that feeds on grass at night and can turn lawns brown within days, especially in Queensland and northern NSW in late summer and autumn.

Curl Grubs

Scarab beetle larvae (Scarabaeidae)

C-shaped, creamy-white beetle larvae that live in soil and eat grass roots, causing patches of turf that die and lift away like loose carpet.

Guide

Common Brisbane Household Pests

A Brisbane-specific overview of the pests residents meet most often, when they are active, and what the subtropical climate, storms, creeks and Queenslander homes mean for pest pressure.

Guide

Understanding Pest Activity After Rain

Why storms and wet weather bring cockroaches, ants, mosquitoes and spiders into homes, what to expect in the days and weeks afterwards, and what to do before and after rain and floods.

Still have a question?

Ask PestMan. We’ll show you any answers we already have — and if we don’t have one yet, your question helps decide what we answer next.

Sources & further reading

PestMan provides general information only and does not replace licensed pest-management, medical, veterinary or structural advice. Always read and follow product labels. Read our disclaimer.