5 Factors That Cause Brown Spots in a Lawn

Pets

• Pet urine and feces are extremely damaging to the surface of a lawn, according to Lowes. Since pet urine contains a high amount of nitrogen, the soil and blades of grass are both affected. Determine if the soil is affected by using a soil pH test. Lowes recommends watering the lawn or flushing it with water within an hour after the area has been contaminated to prevent nitrogen buildup.

Mower Blade

• A mower blade chops down the tip of a blade of grass, giving the lawn a clean, even look. If the mower blade is dull, chipped or broken, the tips of the grass blades get shredded rather than cut. This leads to the grass drying out quickly, even with watering. This situation is easier to diagnose, since brown patches will appear over the entire lawn rather than in isolated areas.

Insects

• Insects feed and live in grassy areas, but certain types of insects can kill patches of grass through feeding. Beetles, for example, begin as grubs, which feed on the grassy areas around them. As the number of insects increases in a particular patch of grass, the grass will eventually turn brown. Small, irregular patches of brown in the lawn are often an indicator of an insect infestation, especially if rings are present within the brown circular patches.

Disease and Soil Conditions

• When the environmental conditions of the soil change, grass is more prone to disease. A disease will first start in yellow patches that eventually turn brown as the disease kills the patches of grass. Soil conditions, including a lack of iron, are also to blame for brown patches of grass. According to Lowes, iron deficiency most often occurs in grass patches near concrete areas, such as a sidewalk or driveway.

Improper Watering

• A common cause for brown patches of grass is lack of water or poor watering. Broken or improperly placed sprinkler heads can leave areas of grass without water. During periods of hot weather, the blades of grass will dry out and eventually turn brown. Inspect the lawn's sprinkler system by turning it on and making sure each sprinkler head overlaps the area next to it just slightly to diagnose if lack of water is the issue. Look for broken sprinkler heads, especially in areas where brown patches have already formed.