Recently I laid a new lawn and it all came up very thick, but over the last week there are patches of browning in my new lawn. What is the cause and how do I repair the problem? 

• There could be several reasons for the brown patches – lack of watering, overwatering, grass grub, dogs going toliet on the lawn or burning from over application of lawn fertiliser.
• Increase watering if you suspect the lawn is not be getting enough water. In summer turn the sprinkler on twice a day, morning and evening.
• To check if the lawn is getting enough water use an empty tuna can placed on the lawn, turn the sprinkler on, time how long it takes to fill the tuna can and that is how long you need to water the lawn for.
• Long deep waterings 2-3 times a week are more beneficial than light sprinklings every night as deep watering encourages roots to penetrate deeper into the soil where light waterings encourage shallow rooting and so more chance of the grass burning off when there is a drought.
• If you are watering at night the brown patches could be a fungal disease, change the watering time to morning so that the lawn has time to dry out before night fall. 
• Apply Debco SaturAid granular soil wetter to help retain moisture in the soil and channel water to the roots. 
• If fertiliser has been applied unevenly and not watered in sufficiently then it can cause burning. Apply a slow release fertiliser such as Tui LawnForce New Lawns on a newly sown lawn or All Purpose for a lawn at least 12 weeks established. 
• Grass grub feed on plant roots and so the tops will die off leaving brown patches. If you dig a spade depth down into the soil you may or may not see grass grub present, small brownish black beetles may start appearing which indicates grass grub. Some grass varieties are bred to be resistant to grass grub. The best time to treat grass grub is spring and autumn, talk to your local garden centre or hardware store for a grass grub control product.  
• Rake out the brown patches, apply Tui Lawn Preparation Mix and then sow lawn seed.