Why Does Grass Turn Brown & Die?

Brown Patch

Brown patch is the name of an actual disease that can infect seemingly healthy grass lawns. View the brown areas of your lawn from above: if they look like a ring of brown grass with green grass in the center, with some white patches at the edge of the circle, it is likely the disease brown patch. The disease is caused by fungi in the soil, and spreads with high day and nighttime temperatures that never drop below 65 degrees Fahrenheit. Poor drainage and high nitrogen levels in the soil also encourage the spread of the fungus.

Carefully controlling the environment in which your grass grows will help to control and eliminate the brown patch fungus. When you water the lawn, do so early in the morning; this will ensure that the grass absorbs the water and the blades themselves dry quicker during the hottest part of the day, so that the excessive moisture doesn't hang around and encourage fungal growth. Rake and bag all clippings from the lawn so that the dead grass doesn't retain moisture or feed the fungus. If possible, reduce shade covering your lawn; higher heat will increase moisture evaporation and kill off fungus.

Brown patch will likely disappear when the conditions leading to its growth have vanished. If not, you may need to treat the fungus itself. If necessary, treat the fungal infection with benomyl or chlorothalonil, two fungicides that combat this disease. Follow specific product instructions or advice from a lawn care professional when applying fungicides.

A number of environmental conditions can lead to brownness in the lawn, including over- or under-watering. Lawns generally need about 1 inch of water per week, and will often get this water from rainfall. If you are experiencing little rain or high temperatures, test the soil; if the top 2 inches of your lawn feel dry to the touch, water thoroughly so that the soil is completely moist. Follow all directions on your chosen fertilizer in regards to applying it to your lawn. Over-saturation with nitrogen or trace elements like iron, all found in fertilizers, will lead the grass to dry out and appear brown, burned and dead.