Why Does Grass Turn Brown Even When It Is Watered & Fertilized Properly?

Soil pH

• Soil that is too acidic or alkaline can cause grass to turn brown despite proper water and fertilizer applications. Grass thrives in soil with a slightly acid to neutral pH of 6.0 to 7.0. When the pH is too low or high, the roots are unable to absorb nutrients even though they are present in the soil. Test the soil pH to determine if it is within range. Soil pH test kits are sold commonly at area garden centers and on-line for as little as $10 to $15 at the time of publication. Cooperative Extension offices will do a soil pH test for homeowners for a fee of $10 to $15. The Extension office can suggest an appropriate soil treatment, if necessary, to bring the soil pH up or down to between 6.0 and 7.0. Lime applications will raise the pH, while sulfur will lower it.

Clay Soil

• Heavy clay soil drains slowly, keeps grass roots wet and deprives them of oxygen. Grass can experience root rot in these conditions, causing it to turn brown and die. Check the drainage capabilities of the soil. Dig a 4-inch deep hole in the lawn that is the same diameter as a large coffee can. Remove the bottom of a large coffee can and press it into the hole. Fill the can up with water to see how quickly it drains. If 2 to 3 inches of water drain out of the can within one hour, poor drainage is not the problem. If less than 2 inches of water is gone, poor drainage may be the problem. Add well-aged cow manure, leaf mold, lime, calcined clay or vermiculite to improve drainage capabilities. Core aerifying the lawn also will help loosen the soil by pulling up small cylindrical soil plugs. A core aerator machine can be rented for the day to complete the task.

White Grubs

• White grubs eat grass roots, causing the grass to turn brown and die. The brown grass commonly occurs in sections that can be extensive when infestations are severe. White grubs are the larvae of beetles. Lawn damage due to white grubs becomes evident toward the end of summer or beginning of autumn. There also may be small holes in the lawn due to skunks and raccoons digging the grubs up to eat. Pull up the damaged turf by grasping the grass along the edge of a brown area by hand. When grubs have eaten the roots, the turf will pull up easily to reveal 1/3- to 1 1/4-inch long white C-shaped worms with brown heads. Treat the lawn with an insecticide designed to treat white grub infestation. Use a preventive white grub insecticide in early summer of the following year to prevent subsequent infestations.

Fungus

• Rhizoctonia fungal disease commonly is called brown patch. The first signs of brown patch fungal disease are circular brown patches of grass. As the fungus progresses, patches of grass as large as 6 feet in diameter turn brown and die. It is most prevalent in humid conditions when temperatures are 75 to 85 degrees F. during the day and less than 68 degrees F. at night. Treat the grass with fungicide and replant areas where the grass dies out completely. Use a grass catcher on the lawn mower to catch the infected clippings. Bag them up and place them in the garbage. Prune trees and shrubs around and in the yard for better air circulation and sunlight exposure.