What Causes Brown Grass?

FERTILIZER BURN

Fertilizer burn typically will appear within a week of an over application or spill of your fertilizer. Fertilizer is made up of a variety of salts which, when applied too heavily, dehydrates and kills the lawn. Recovery is quick when the brown patch becomes accented by a band of very vigorous, dark green grass that surrounds the damaged area.

Controls: When the spill occurs, pick up any excess fertilizer; you can then leach the fertilizer from the ground by soaking the area with water and allowing it to drain. Repeat several times.

GRUB DAMAGE

This is one of the most common lawn problems we see. Grubs are the larvae of beetles. Many types of grubs feed on the roots or crowns of your lawn causing the grass to brown out and die. Grub damage can be confirmed when areas of sod can be lifted easily and roots are not present. Grub presence is also signified by skunk or raccoon diggings in the lawn. These are small holes that have been dug in pursuit of the grubs.

Controls: Unfortunately, there are limited controls for grubs. A product containing Diazinon is best applied at the first sign of any damage. Apply the product, then water. This will carry the insecticide down in to the area that the grubs are feeding. Often a follow-up application is necessary.

CHINCH BUGS

Chinch bug invasion usually begins along the edges of the lawn. As they suck juices from the grass they inject a poison which acts much like a weed killer. The grass wilts, turns yellow, then dries out and dies. Chinch bugs are sun and heat loving, seldom will you find them in a shady lawn. Both the immature nymphs and the adults cause damage. To test for chinch bug presence, remove both ends of a tin can, push it 2-3 inches into the ground. Keep the can filled with water for 10 minutes. Very small, black to brown insects with white wings will float to the surface if they are present.

Controls: As soon as you identify the problem, water well. This will bring the insects to the surface; apply an insecticide at this time. Use a product containing Diazinon to control these pests. Reapply in 6-8 weeks to catch the new hatchlings.

BROWN PATCH

This is a fungus that flourishes during periods when the temperature is between 75 and 85 degrees and when the humidity levels are high. Brown patch is typically identified by a dark purplish ring that appears around the outer margin of the infected area. Typically, only the blades are affected and recovery is quick as the crowns soon push out new growth. You can reduce your chances of infection by reducing the quantity of fertilizer used during high risk times. This will reduce the amount of soft, tender growth which is most susceptible.

Controls: Control with a fungicide that contains pentachloronitrobenzene (PCBN) or chlorothalonil. Repeat as directed. The occurrence of many lawn fungi can be reduced by watering in the early morning instead of the evening.

DOLLAR SPOT

Dollar spot is most prevalent during warm and wet weather. The light brown to straw colored circular spots range in size from 1-6 inches in diameter. The infected blades have small, light brown spots with reddish brown borders, that extend across the entire leaf. Infections occur most in lawns under stress. Seldomly is the damage permanent. Recovery typically takes a few weeks.

Controls: Control with a fungicide that contains pentachloronitrobenzene (PCBN) or chlorothalonil. Repeat as directed. The occurrence of many lawn fungi can be reduced by watering in the early morning instead of the evening.

FUSARIUM BLIGHT

This fungus attacks during the summer when temperatures are over 75 degrees. The hottest areas in the lawn typically show signs first. The grass in affected areas turns light green first then straw brown. Often the fungus forms a ring leaving a patch of green in the center. If left uncontrolled, the damage can reoccur year after year. Remove excess thatch, don’t over fertilize, and keep the lawn healthy to prevent infection.

Controls: Complete control is difficult. To reduce the chance of recurrence, remove dead areas, reseed with resistant types of grass., and keep your lawn healthy. In California, there is not an available control for over the counter sales.

SOD WEB WORM

This little pest causes irregular patches of dead grass by chewing the blades of grass off at ground level. These little caterpillars hatch from eggs in may through September and attack the hottest parts of the yard first. In damaged areas look for white, silken tubes at the soil level. You will find the caterpillars feeding on your grass at night or on overcast days. To anticipate potential problems, watch for small white or grayish moths flying over your lawn in a zig zag pattern.

Controls: These pests are best controlled with an insecticide containing Orthene® or Diazinon. First, remove all dead material and water the lawn well; then, apply the insecticide in mid to late afternoon as this is when the insects are most active. Damaged lawns can recover quickly when damaged.

DROUGHT

Lack of rainfall or irrigation can cause grassy lawns to go into a dormant state.  South facing lawns and slopes may begin to turn brown before other parts of the lawn from exposure.  These lawns can survive drought periods for a few weeks with intermittent rainfall.  Note: drought-stressed lawns are more susceptible to mechanical and heat damage.  To properly water a lawn, apply the equivalent of 1″ of rainfall per week and water in the early morning so the turf has a chance to dry off by night fall.  Avoid frequent shallow watering.

INSECTS AND DISEASE

The common lawn insects and disease can cause various patterns of discoloration and browning.  Become aware of the signs to look for and the time of year that they are active in order to diagnose them accurately.  Correct diagnosis is essential for treatment which may include the use of fungicides and/or insecticides as well as cultural methods of control.

POOR OR COMPACTED SOIL

If soil is so poor that roots can’t penetrate and fail to establish, brown areas may appear while the neighbors’ lawns look fine.  Soil in areas frequently trafficked, such as footprints or animal paths, can become compacted and lead to a decline in lawn quality.

MOWING

Scalping on slopes or on uneven terrain, mowing too short, and filling the mower with fuel on the lawn can cause brown areas. Be aware of slopes and depressions in the lawn and mow accordingly. Change mowing direction about every other mowing to avoid scalping. Fill mowers with fuel on driveways or other hard surfaces to avoid spills in the lawn. Cutting your lawn to short could burn the lawn. Mowing no more than 2 inches from the ground will help keep down stress.

FERTILIZER

Misapplying fertilizer, filling the spreader on the lawn, and fertilizer spills can all cause brown areas.  Fill spreaders on the driveway or other hard surfaces and clean up spills. Make sure the spreader is calibrated correctly and is being used properly by making header strips and shutting of the spreader on turns. Too much fertilizer can turn your lawn brown, by burning it. 

OVER WATERING

Water conservation isn’t the only reason to limit the amount of water you give your lawn. Over watering is also bad for your lawn’s health and can contribute to the development of fungus and disease, turning your lawn brown. Many people, however, don’t know that they’re over watering. Some types of grass require more water than others, and environmental factors, such as temperature, humidity, and wind, can dramatically affect how frequently you need to water your lawn. Fortunately, the most accurate way to determine whether your lawn needs water is: When grass needs water, it will begin to take on a blue-gray tint, and the older leaf blades on the plant will begin to curl up or wilt. In addition, footprints will remain on the grass for longer than usual, as the grass won’t jump back.