Brown Spots in an Evergreen-Type Lawn

Water

• Lack of water is the primary cause of brown spot. If you have an irrigation system, it is a good idea to watch it when it goes off at least once a month. Sometimes a head needs to be replaced or put on a riser because a plant has grown up in front of it and blocked the spray. Every grass species has different needs but some, such as St. Augustine, need 2 to 3 inches of water weekly, or it will turn brown. You may just need to increase the frequency of your waterings. Areas where there are objects under the sod or where tree roots intrude will also need extra water, since sod root growth is shallow in those spots.

Dogs

• Fido may be your best friend, but his potty habits can play havoc with your turf. Even if you don't have a dog, the bathroom activities of roaming canines can be the cause of brown turf. Excess urine causes a concentration of nitrogen and dead brown patches. This is what happens when your animal has a favorite spot. Infrequent urine applications cause thick green spots in the lawn. Female dogs are the main culprits of brown spot, as they tend to eliminate in the same area daily. Fencing or training the dog to go in a designated area can prevent brown spot caused by the family pet.

Chinch Bugs and Nymphs

• Chinch bugs are most commonly found in the southern states. Grasses that have a thick thatch are more prone to housing these pests, which live near the surface of the soil. The adult bug is winged, with an oval, elongated body and black markings. The nymphs are the cause of the damage, as they feed by sucking plant juices. Chinch bug feeding causes the blades of grass to get yellow spots and then die, turning brown. They primarily feed in the summer, and the patches of brown grass will spread as the nymphs move to greener pastures. Applying an insecticide for control is only recommended when the infestation is severe. Thatching helps remove the thick layer in which the bugs hide.

Brown Patch Fungus Disease

• Brown patch disease is caused by Rhizoctonia, a fungus that appears when lawns are over-watered. The spots in the lawn may be several feet across and begin to brown at the edges of the spot. Often, the center remains green for awhile but will thin out considerably. When the grass is dewy or damp, you can see the web of fungal growth across the blades. The disease only occurs when temperatures are hot and humidity is high. Watering early in the day so the leaf blades have time to dry out, along with fertilizing only as much as is necessary, can minimize the growth of the fungus.