Dollar Spot is a turf disease effecting many different turf varieties. As its name suggests, the appearance of this disease is usually identifiable as dollar sized spots of discoloured grass appearing within your lawn. Up close, the discoloured leaves will have straw coloured lesions with red/brown edges to them. If left to spread the spots will get larger and form bigger patches of affected grass.
Another identifying feature of Dollar Spot is the web like fine threads that form through the leaves of your lawn on colder mornings. These webs will disappear as the day warms up, but these threads are called mycelium threads and are a product of the fungal pathogen known as Sclerotinia Homoeocarpa.
Dollar Spot occurs when there is additional moisture present on warmer days and the cool nights of spring and autumn. Excessive amounts of thatch build up, poor drainage and watering your lawn too often are common factors that can result in the spots appearing. Dollar Spot is much more common in turf under intensely managed conditions, so is commonly experienced on golf courses.
So often with fungal diseases the best remedy is simply good lawn care practices.
We generally do not recommend treating with fungicides unless the issue continues to persist after implementing the treatment options above. By treating the cause, you should be able to get Dollar Spot under control without the use of a fungicide.
Some fungicide options you might want to consider however are Mancozeb and Zaleton Systemic Fungicide, which you can purchase at Bunnings or commercial options Bumper 625 and Chief Aquaflo.