Lawn grubs is a generic term used by Australians for lawn beetles, caterpillars, and larvae. Proper identification is the first step to controlling them. Army worm, a caterpillar type, is probably the one that strikes fear into most lawn owners. Army worm is a perfect name, as they move by the thousands from one lawn to the next. You will usually notice when you have them. This is what they look like. (Pictured Below)
If you see brown patches appearing from mid to late summer and you suspect its caused by army worm, flood the area with water and they will come to the surface. Although they may occasionally attack a Zoysia lawn, they generally prefer other types of lawn including Buffalo, Kikuyu, and Couch. There are various forms of controls that you can buy to kill these pests. Apply them just before dusk and repeat weekly until they are dead.
The other lawn damaging caterpillar in Australia is the Sod Webworm. They harm cool season turf types far more, but still can cause significant damage to warm season lawns like buffalo, Kikuyu and Couch, but rarely Zoysia. If you see dead patches and silken webs on the lawn in the morning, you may have web worm. After applying the chemical to kill lawn web worm, water it in well.
Not all lawn pests are caterpillars. Black beetle can cause damage if they are in large numbers. In smaller populations they rarely cause significant damage. Black Beetles start life as a curl grub or c shaped larvae. At the black beetle stage they may eat your ornamental plants and a little of your lawn, but its at the larvae stage in Spring and Autumn that they live under your turf and eat the roots and rhyzomes of your lawn. If Black beetle is causing significant damage, then an inexpensive powder insecticide can be applied to the soil and watered in whenever the pests are active.
Lawn diseases in Australia can make a lawn look unsightly, but if you have a Couch, Kikuyu, Buffalo, or Zoysia type lawn, then the damage will rarely be widespread and irreversible. Cool climate turf types like Fescue, Rye Grass, and Kentucky Bluegrass can be damaged far more by disease, and can sometimes be wiped out, as they generally do not repair themselves well.
With warm season lawns, fungus diseases such as grey leaf spot, or Dollar spot can sometimes cause unsightly problems, usually in summer, so if the disease bothers you, use a Fungicide treatment.
The best way to keep these insects and diseases away from your lawn is to do proper maintenance, proper watering, proper mowing, proper fertilising and so on, but sometimes even with that, insects and disease can cause significant damage so be vigilant, treat infestations, but don’t panic.
A well maintained lawn can better stand up to the abuse of insects and diseases. If insect or disease damage does occur, fertilise and water the lawn well, and you will find it will generally repair itself.