Question
We have just had our new lawn laid (4weeks ago). thoroughly watering it and are disappointed to see quite a lot of brown patches appearing.  We had top soil put down first.  Can you give me the cause of this and how do I treat it.

Many thanks

Answer
If the brown patches are circular in pattern (or roughly so) and if you think that you have over watered (rather than under watered), it is quite possible that the lawn has a fungus disease like brown patch. You will need to revise your watering routine; once a day and early enough so that any free water is dried out before the sun goes down. An application of chemical may be needed; if so, you need to contact the County Extension Office because such activities may be tightly regulated.
If the shape of the brown patches suggest that the sprinkler system is failing and if you feel that you have been under watering rather than the other way around, then the patches are showing moisture stress. It takes a bit of imagination but if the brown patch looks like an hour glass, or two concave surfaces placed back to back, then it suggests that two full- or part- circle heads are not overlapping. The sprinkler system needs to be looked at.
I hope that this all helps.