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A garden with lush green grass and raised entertaining area
Grubs, worms and diseases – here’s the best way to remove and prevent these persistent pests.

Uninvited invaders

We love our lawns. But sometimes, despite our efforts, pests and diseases can attack and ruin our hard work. It’s important to recognise the early signs or symptoms of these issues so you can treat and prevent the spread. Here’s how to identify and treat common lawn pests and diseases.

Curl grubs (Heteronychus arator)

These grubs are silent killers. You can’t see them, and if you don’t notice signs of them early in the season, they can do a lot of damage in a very short period of time. Curl grubs are the larvae of scarab beetles, which include the African Black Beetle and Argentinian Scarab Beetle, both introduced pests. The larvae are white or cream-coloured with a light brown head. They curl into a c-shape when disturbed.

They remain in the soil where they feed on the roots, causing the above-ground lawn to die off in patches. With severe infestations, the brown, dead patches can be rolled back like a carpet. Keep an eye out for any brown patches appearing in the lawn. If you suspect it’s curl grubs, lay a wet towel over the lawn and leave overnight and grubs will come to the surface the next morning. Treat with a specific lawn grub killer.

Two grubs in the dirt

Lawn armyworm (Lepidoptera spp.)

This pest is a voracious lawn feeder. It chews on leaf blades and is often found in large numbers, where they ‘march’ their way through the lawn and completely decimate it in the process – sometimes in a matter of days! Dead, brown patches appear on the lawn and continue to spread rapidly.

Their dull-green appearance with distinctive stripes along the top of the body allows them to easily camouflage in the lawn. To test if you have armyworm, pour a bucket of soapy water over the affected area. After 10 minutes, you will see them thrashing about. 

Treat with products that contain the active bifenthrin or beta-cyfluthrin.

A caterpillar on a green plant stalk

Brown patch (Rhizoctonia solani)

An aptly named fungal disease that appears as small brown patches in the lawn. If left untreated, the disease spreads, becoming irregular-shaped to a metre or more in diameter.

This disease is prevalent in the warmer months, particularly in areas with high humidity. It is exacerbated if lawns are watered late in the evening, allowing the water droplets to remain on the leaves – ideal conditions for the fungus to take hold and spread. Leaf blades brown and die, with the lower part of the leaf darkening and rotting. 

Treat with a suitable fungicide and stop watering until the fungus subsides. Once under control, only water in the morning. Use a fork or corer to aerate the entire lawn, particularly around the affected areas.

An area of grass with faded brown patches

Dollar spot 

A common and widespread disease that is identifiable easily due to the discoloured ‘dollar’ sized spots in the lawn. If left untreated, the spots will grow and may coalesce to form larger patches. Close up, the leaf blades are straw-coloured and have red-brown edges.

The disease is prevalent during the spring and autumn, when the days are warm, but nights are cool. Poor cultural conditions such as compaction, excessive irrigation, and a build up of thatch can also contribute to the occurrence of dollar spot.

To treat dollar spot, improve the health of the lawn by aerating, dethatching, and watering as needed. If needed, follow up with an application of Mancozeb.

An area of grass with faded brown patches

Safety first

When using any products to deal with garden pests and diseases, always read the label, follow the instructions carefully and wear suitable protective equipment. Store out of the reach of children and pets.

Noticing some extra growth in your lawn?

If weeds are invading your yard, check out our guide on how to treat common lawn weeds.


Photo Credit: GAP Photos, Getty Images and Alamy Stock Photo


Health & Safety

Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page.

When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.