What Are the Causes of Brown & Short Dead Grass?

Insect Damage

• Mealybugs, nematodes, billbugs and chinch bugs feed on roots and foliage, causing stunted growth and patches of browning grass that vary from small spots to large swaths in the lawn. Monitor the lawn for evidence of insect activity. Once the insect is identified, you need to decide whether to apply a pesticide. If the infestation is small, reduce the amount of nitrogen in the fertilizer. High nitrogen levels encourage reproduction in some insects.

Diseases

• If your lawn was sown recently from seed, the young turfgrass seedlings might be suffering from damping off caused by defective, diseased seeds or sowing seeds too densely. This condition can affect any species of grass and causes the seedlings to become brown and stunted. Before reseeding, make sure the soil is well drained and aerated. Treat the seeds with fungicide before planting and at the first symptoms of damping off. Use fungicides containing captan, mefenoxam or mancozeb to treat seeds and alternate the products to keep pathogens such a pythium, fusarium and rhizoctonia from developing immunity.

Fertilizer and Herbicides

• Problems with lawn grasses often can be traced to too much, too little or the wrong kind of fertilizer. Too much fertilizer, especially in spring and summer, can burn the grass, turning it brown and stubby. Use a slow-release fertilizer every other feeding to avoid applying too much nitrogen to the grass. Always read herbicide labels to be sure the product is safe to use on the species of grass in your yard. Herbicides containing glyphosate kill all vegetation, including desirable lawn grasses. Pre-emergent and postemergent herbicides control weeds before and after they germinate, but not all of these herbicides are suitable for all species of grass. The wrong type of herbicide or one applied at the wrong time can make the grass first yellow then brown, and it can cause stunted growth.

Water

• Improper watering, especially during periods of extended dry weather, can cause turfgrasses to develop shallow root systems and weak, stunted growth. During a drought, the grass often turns brown. Water the lawn deeply and slowly about once per week rather than watering shallowly every other day. Check the soil to a depth of 6 to 8 inches to make sure the soil is moist. Water more frequently during drought, if necessary, but be careful not to overwater the grass. Water in the morning to avoid evaporation and never water at night, because wet foliage is more susceptible to disease. Cool-season grass is less drought-resistant than warm-season grass and requires more water.