Brown patches on lawns can have a variety of causes, including animal and human damage, poor growing conditions, and diseases and pests. Animal and human damage is the first cause to investigate.
Human damage can result from dull mower blades or setting the mower too low. To correct this, sharpen mower blades or adjust the blade height. Another human cause of browning is chemicals. The improper application of fertilizer and weed killers damages the grass.
Animal urine can cause grass death. Dogs are the most common, but other animals including large birds and wildlife can also damage lawns.
Poor growing conditions, including objects buried under the grass and drought, also cause brown spots. Another cause of brown spots due to growing conditions is a mix of different species of grass within the lawn. Different species of grass have different dormancy cycles and cause brown patches.
Pests and fungal infections can also cause patchy death in lawns. Grubs are active in mid to late summer. A grub control product can help correct this issue. In addition, cinch bugs are active in hot sunny areas and can cause large amounts of damage rapidly.
Fungal diseases flourish in damp, humid areas and can cause brown patches. Fungal infections peak in early spring and midsummer during hot humid nights. Spotted or irregular patchy areas on grass blades within the dying area indicate a fungal infection. To control a fungus, increase drainage in the affected area and water less frequently.