Landscaping - advice for putting new turf in backyard

[Mr Crudley]

Maybe be African black beetles eating the roots?

 

[gippyz]

You might be thinking of the blackheaded cockchafer but I don't think that's the culprit here. That looks like it might have been burnt from over fertilising or dog's piss

Didn’t use any fertiliser, so could be the dog pissing there.. it seems to be spreading though which is very concerning.