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CAUSES OF BROWN SPOTS IN TURF

Brown spots are one of the most frustrating lawn problems. If you can discount an obvious source – dog urine, for example, the spots seem to appear out or nowhere and it’s difficult to figure out what caused them. Here are some common reasons lawns turn brown in our area.

  • Unsharpened mower blades shred the tips of grass plants, allowing them to dry out rapidly. This quickly creates a brown appearance, especially during warm weather. Sharpening the blades corrects the problem.
  • Scalped areas turn brown because they’re not mowed correctly. Scalping occurs when the mower runs over an uneven lawn, removing excessive grass from the tops of high spots. Soil, then turf, dries out because little grass canopy remains to protect it against the sun’s heat. Try raising the mowing height in these places to reduce the problem.
  • Walls and hot pavement can reflect the sun’s heat onto nearby grass causing it to dry and brown. Soaking these areas more frequently helps replace lost moisture.
  • Hot exhaust can also produce brown spots, especially if the mower is left running in place on the turf. Gasoline and oil spills cause sudden death of grass plants; so can objects left on the lawn during sunny weather.
  • Tree roots compete with grass roots for water. One solution is to water the competitive areas more often or more heavily to compensate for the loss. In the long run, it might be simpler to remove the grass altogether from this difficult site and replace it with an organic mulch.
  • Soil compaction, the tight packing together of soils particles, restricts root growth. If roots don’t grow, neither do the tops. Heavy clay soils, with which our region is blessed, naturally tend to be compacted. Foot and equipment traffic, heavy rain and irrigation can also cause or worsen compaction. Check for soil compaction by inserting a long screwdriver or rod into the troubled spots. If you feel resistance, suspect compacted soil. Core aeration, in the spring, fall or both, can help relieve it.
  • Buried debris, such as rocks, bricks or lumber often produce brown spots. The amount of soil covering these objects often is too shallow for good root penetration. Because the roots don’t have sufficient area to explore for water they, and then the grass, dry out. Probe the soil with a long screwdriver or dig in the affected area to determine if this is the cause of the problem and remove it.