What are These Brown Spots on my Lawn?
You’ve watered, and mowed, and fertilized. And yet, those ugly brown spots. What can cause those patches? Let us count the ways.
Fungal Diseases
Fungi just love heat and humidity. Here are two common species that could be the source of your dead grass:
- Brown Patch (Rhizoctonia solani)
Symptoms: irregular, brownish-yellow patches ranging six inches to several feet across, often with a “smoke ring” border on the outer edge. Up close, the leaves show tan lesions with dark brown borders. - Dollar Spot (Clarireedia homoeocarpa)
Symptoms: appear as small white or tan spots the size of a dollar coin, though the spots can also be up to six inches wide and sunken. Leaves have white or light-tan lesions with light reddish brown margins. When early-morning dew covers the grass, white, cottony, mycelium can often be seen.
Insects
Grubs, chinch bugs, and caterpillars can cause brown spots. One clue it’s a pest problem? The perimeters of the spots are much less uniform than those caused by fungi, since the bugs chew in all different directions. Also, pests may leave tiny bits of live green grass inside the brown spots.
Poor Lawn Conditions or Maintenance
Dull mower blades, over- or under-watering, poor drainage, compacted or poor-quality soil, over-application or mis-timing of fertilizers—any of these can result in patches of dead or dying grass.
Pets
The high nitrogen content in animal urine can burn the grass, usually causing yellow spots ringed with bright green edges (where the diluted nitrogen acts as a fertilizer).
WHAT TO DO?
Resist the urge to throw everything at the problem. The faulty selection or timing of pesticides or fungicides can worsen the problem. A good soak with the hose might seem like a good idea—unless the source of your woes is a fungus that thrives in high moisture.
Instead, call in lawn care professionals. They can determine the best fix—such as organic treatments, aeration of the lawn, and over-seeding with pathogenresistant turf varieties. What’s more, they can recommend a lawn care plan that will make your grass far less vulnerable to diseases and pests in the future.
