Sloped areas also are prone to browning. Water usually runs off the slope before it has had a chance to sink in and the lawn dries out. Aerating the sloped areas helps move water into the soil. It reduces soil compaction, which resists downward water movement. Irrigating slopes with a soaker hose adds water slowly and may improve its penetration.
Tree roots compete with grass roots for water.
One solution is to water the competitive areas more often or more heavily to compensate for the loss. In the long run, it might be simpler to remove the grass altogether from this difficult site and replace it with an organic mulch. Hot exhaust can also produce brown spots, especially if the mower is left running in place on the turf. Walls and hot pavement can reflect the sun's heat onto nearby grass causing it to dry and brown. Soaking these areas more frequently helps replace lost moisture.