Lawn health, pests and diseases

Like all plants, lawns can suffer from sickness and attack by pests. They can also be damaged by establishment of weeds. The best way to reduce these problems is to have a regular lawn maintenance program. This consists of frequent mowing and regular fertilisation, soil treatment and water management. Plus early control of any pests, diseases or weeds that occur. Below are some of the health problems commonly encountered in Sydney.


White Curl Grubs are beetle larvae, that look like partly eaten, little grey-white donuts. They eat the bases of grass stems and the roots, which kills the grass. They can do a lot of damage. The damage is increased when birds like magpies come digging for the grubs. On the one hand, they help by eating the grubs, but they don’t get them all and can make a mess trying.

Caterpillars of various kinds, such as Army Worm, Sod-Web Worm and Cut Worm eat the grass blades. During the day they hide in the thatch of dry grass below the green stems. They come out at night to devour your precious turf.

Ants of different species make nest holes and tunnels in lawns. They can make a mess, and the biting varieties can be a risk to people. They like dry thin lawns, so once again, regular lawn care is a good preventive.

African Lawn Beetles are only a problem if lawns are uncared for. In a healthy lawn they tunnel through the soil and eat lawn roots. However they don’t work intensely in one spot, rather they spread their activity. This has the result of aerating the soil, allowing water to penetrate, and stimulating new root growth to replace the eaten ones. All this benefits the lawns. However a poorly maintained lawn may end up with too many African Lawn Beetles, and in this case they need controlling.

Fungus diseases

If you see spots, patches and rings of dead, grey or brown grass, you may have a fungal infection. These infections can occur more at particular times of year and under particular conditions of imbalance. Examples are warm humid weather favours Anthracnose, Black Leaf Spot and Pythium. Summer and Autumn is the time for Brown Patch and Red Thread, while spring and summer favour Fairy Rings and Rolf’s Disease. Winter Fusarium likes cooler weather and poorly aerated soils that too high in nitrogen while too low in potassium and phosphorus. You can get Spring Dead Spot in spring and autumn when it’s cool. Take All Patch also like cool wet conditions and poorly drained soil. All of these diseases can be treated with appropriate fungicides, and reduced with proper lawn maintenance.


There are so many weeds it would be impossible to go into all of them here. A rule of thumb is that, like all problems, they can be minimised with a regular, professional lawn care regime that deals with mowing, feeding, water, top dressing, soil treatments and repair of bare patches. A lush, continuous lawn on well aerated nutritious soil is the best defence. However if weeds do gain a hold, there are different ways they can be dealt with. It does require know-how to avoid overuse of poisons or ineffective methods.

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