Red thread is caused by a fungus called Laetisaria fuciformis. Lawns infected by this fungi may have a pink-to-reddish cast when viewed from a distance. The red threads will grow around an inch past the hight of the lawn. The areas of infected grass will look like it has been bleached in colour. If the lawn condition is moist, then the fungus will form patches of pink branching threads. These red thread patches may join together to create one large infected area.  

To help prevent red thread you can take the following steps:
1. make sure that your lawn has the proper Nitrogen level. Lawns that are lacking in Nitrogen have more of a chance to red thread infection.
2. Aerate the lawn which helps drainage and opens airways to let oxygen and other nutrients flow to the roots.
3. Remove all areas of thatch from the lawn. Thatch limits the amount of air, light and nutrients to the grass roots.