Brown patches in your Sir Walter lawn in Perth are most commonly caused by water. Either the lawn is not getting enough water, or the water is not penetrating into the soil. Check the following:
- Test your reticulation system to ensure all sprinklers are working and covering the whole lawn area.
- Put water measuring cups onto the lawn, turn on the reticulation and let it run for its usual time. Measure how much water was applied. It should be at least 10mm (15mm is ideal for Perth) applied twice a week.
- If the watering system is OK, now check for water penetration. Choose a brown patch of lawn and dig open the soil slightly, just enough to put your hand in. Check to feel if the soil is moist to a depth of about 60-70mm. Repeat this procedure in a green patch of lawn. If the soil is noticeably drier in the brown area, the problem is with water penetration.
Usually these checks will uncover the cause of the brown patches.
Ensure that you are following the recommended soil wetting program and fertiliser program.