Grass can become unhealthy and die out for a number of reasons such as fungal diseases, thatch problems, improper grass selection or pests. Diagnosing the problem will help you either provide proper lawn treatment or prevent the problem from occurring in the future. Reseeding over an unhealthy lawn without fixing the underlining cause will only result in the problems from reoccurring,
Lawn diseases such as melting out, fusarium blight, summer patch, fairy rings and rust can kill patches or large areas of grass, according to North Dakota State University. Typically, fungal diseases occur after moist weather in the spring. However, both typhula blight and fusarium blight can infect lawns in the late summer months. Look for grass discoloration, tan patches of grass or rings of dying grass in the yard. Treatment generally consists of a fungicide application or digging up diseased grass and reseeding the area.
Thatch is an accumulation of dead and living organic matter between the grass and soil. A thatch layer that is less than 1/2 inch thick benefits grass by protecting blades from foot traffic and locking in soil moisture. However, yards that have a layer that is over 1/2 inch thick suffer from numerous problems, according to the University of California. A thick layer of thatch prevents grass from absorbing fertilizer and water. Lack of air circulation in the thick thatch, can be the underlining problem behind a number of diseases. Grass can die out from lack of nutrients or from pests. Remove your thick layer of thatch at the beginning of your grass type's growing season.
Oftentimes, gardeners choose a grass type that is inappropriate for their climate, soil or yard. There are two main types of grass: Cool season and warm season grass. Cool season has a difficult time growing in the southern United States, because of the warm weather. Warm season grass cannot survive cold weather conditions. Also, the soil pH range in your lawn must match up with your grass' preferred range in order for the soil to absorb nutrients. Furthermore, avoid planting a grass type such as Kentucky bluegrass that cannot live in shade in low light areas of the yard. Fescue types perform much better in the shade.
Pests like armyworms, white grubs, chinch bugs, sod webworms and cut worms eat away at grass blades and roots. Not only do the chew marks kill off grass, but the wounds created in the grass blades allow for harmful pathogens to enter and cause an infection. Sift through your soil or underneath the grass to determine what type of pest has infested the lawn. Spray a pesticide that is chemically formulated to kill the invading pest.