Question
collarenebrri.nsw,2833. The winter is cold (can get below0, with plenty of frost,and summer is very hot well into the 40's. My lawn is dying off sarted in one area is getting bigger each year. i am having the soil tested , result has not come through yet. Seems to be dying off from the roots. Could send a photo but new to the internet and dont know how. can you help me?

Answer
A few things that I can think of:

1. is the lawn green in spring only to turn brown in summer ?

possible explanation: your lawn has been invaded by a cool season grass which expands agressively in spring. It crowds out the desireable lawn grasses. During hot summer months the lawn area goes dormant (turn brown). This due to high temperatures for which the grass is not competitive.

solution: erdicate grass in early spring when it first green up. do this with a contact herbicide intended to kill grass as well as weeds (will typically contain glysophate, such as "Round-Up"). Avoid using products intended for patios, walkways etc as they contain salt based weed killers which prevent grass sowing for 9-12 months. Ask a good garden center. Replant/resow need lawn seeds in early summer which is hardy to your area and which perform well in summer. again, a local garden center may recommend specific lawn seeds.

2. insects: grubs

possible explanation: grubs of the japanese beatle will eat the roots of the grass. If you can lift the grass up like a carpet (severed roots) then this is possibly the explanation. you can dig into the root zone between green and brown areas and look for c-shaped white or pink maggits. If you find more than 3-5 per sq feet then consider control.

solution: apply an insecticide rated for grubs of japanese beatles. in the USA there is a product called Grub-Ex which is based on the active ingredience Merit (also a trade name). Merit is very effective. should be applied mid summer. two applications may be required. You can also consider organic approaches such as milky spores or populating the yard with beneficial nematodes. both are living mircoscopic organisms which will infiltrate, attack, and kill the grubs. One application will generally last 10 years but take about 12-18 months to be fully effective. Check with local garden center for availability. In the USA, beneficial nematodes are sold over the internet, too.

I hope above gave you some ideas to look for.
Kenneth