Brown spots in your once verdant green lawn can be more than just an eyesore, they are also likely a sign of an unaddressed lawn health problem. Of course, many of the most common is caused by things that can escalate from a seemingly minor concern into a major problem in no time flat!

Especially if you aren’t sure how they got there or what you can do about them. It’s certainly not the time for procrastination!

Of course, there are a lot of things that can cause brown spots in your lawn. This means that the first step toward treating them is to identify the cause, which requires a thorough approach. 

We decided to take the time to look at the most common causes of brown spots as well as how to best treat them to restore your lush green lawn.

Lawn Brown Spots Caused By Fungus

Fungal problems are one of the most common causes of brown spots on a lawn. They usually show up as irregular patches, that gradually spread over time. Especially during warm, wet, and prolonged humid weather.

If the fungal disease has been active for a long time, you might even see the inside of the brown patch starting to recover. Sometimes it can even leave a ring of dead grass around it. Your lawn might even start to recover during a stretch of dry weather.

Extremely rainy or humid weather can easily encourage fungal outbreaks. Especially if there is a notable lack of sunlight or the area has relatively poor air circulation. 

While you can never 100% control the weather, there are a few proactive things you can do to protect your lawn against fungus. 

This starts with carefully applying a high-quality lawn fungicide according to the label directions. Some are even specially formulated to not only treat active diseases but also to help prevent future problems from listed fungi.

Once the fungal presence has been eliminated from the surface of your lawn, and the underlying layers of the turf, you can take additional measures to prevent a recurrence.

This usually calls for simple things like aerating your lawn with a tine aerator and adjusting your irrigation schedule. Adding a simple rain sensor to your lawn’s sprinkler system will go a long way toward preventing the overly wet conditions that promote many types of lawn fungus.

Cutting your lawn for the prevailing weather conditions and keeping the grass short also makes your turf inhospitable to soil fungi.

Grubs & Burrowing Pests

Grubs are the larvae of larger insects. Soil-borne grubs can damage grass by eating tender roots. As their infestation in your turf continues to grow it can lead to small brown patches that pervasively spread as they develop. Since they tend to radiate out from a central point, a lot of brown patches in a lawn caused by grubs will broaden in a relatively uniform shape.

Many times, the brown patches in your lawn are caused by grubs that will feel sponge-like. When raked it might even roll up the layers of turf as there are no roots securing the dead turf to the subsoil.  

Eliminating an existing grub problem typically requires a specially formulated pesticide meant to kill grubs. If you use a broadband pesticide, it can kill many of the beneficial insects that live on your turf. It’s best to apply the grub insecticide in the spring, and again in the fall as a preventive measure.  

Once the grub infestation in your lawn has been eliminated, you might want to consider resodding the area to rapidly establish the presence of healthy, mature turf.

Brown Spots Caused By Dog Urine

Dog urine burns are probably the most common cause of brown spots on the lawn. It is more likely if you have a female dog or a male dog who has a habit of urinating in one spot. Dog urine burns are typically caused by the high amount of nitrogen in the urine, as well as salts and acidity, which alter the soil chemistry. You can usually spot a dog urine burn by brown centers and dark green outer rings.

Fortunately, lawn brown spots caused by dog urine are so common, that there are plenty of lawn care restorative products. This includes specially formulated lawn treatments and grass seeds that will bring the spot back as fast as possible.

Though you will still need to give your dog an alternative place to urinate, or you will just end up dealing with a recurring problem. Some experienced dog owners will go so far as to create a small gravel patch in their backyard and then simply train the dog to urinate there every time they need to go outside.

Lawn Brown Spots Caused By Weed Dieback

Brown spots can also develop in your lawn when annual weeds like crabgrass, annual bluegrass, and foxtail start to prematurely die back in late summer or early fall. Proper lawn maintenance to prevent these weeds and deal with them before they spread will prevent these problems.

If your region stays relatively warm during the summer, you might want to consider reseeding or sodding the dead spots after remediating the weed presence. If your area experienced deep cold winters, you should note the areas. Then address them again as soon as possible the next spring by reseeding with a vigorous grass seed blend that has a high percentage of nurse grass like annual ryegrass.

Brown Spots Caused By Foot Traffic

Some parts of the lawn get to tread on more than others. This can damage the grass, as well as compact the underlying turf that supports it. In a time like this, you will first need to redirect foot traffic, likely for the remainder of the growing season. Then you can use a tine aerator to loosen the turf soil before reseeding.

Brown Spots Caused By Splash Pools & Toys

Splash pools, water slides, and even inflatable bouncy castles that are left too long on your lawn can starve the underlying grass of the sunlight it needs to thrive. This can kill large areas, leaving brown spots and areas of turf where the microbial culture is out of balance.

If there are still some yellow and green blades of grass left in the area, you might be able to overseed the brown spot and the grass will naturally rebuild its presence. This can happen faster if you have a “Creeping” type of grass like Creeping Red Fescue” which gradually propagates itself via underground runners.  

Brown Spots In Your Lawn Caused By Thatch Buildup

When you cut your lawn with a side discharge lawn mower, small pieces of harvested grass blades are inevitably left behind. If your mower has a mulching feature, these pieces of grass are usually small enough to decompose back into the turf. If the grass clippings are overly long, they can dry out and turn thatch.

If thatch is allowed to buildup into a thick mat it can start to choke out the surrounding grass. It can even prevent moisture from soaking into the turf to feed the roots of your grass causing thinning and eventually large brown spots.   

If you catch it early, you can simply dethatch your lawn with a dethatcher. Running it over with a tine aerator can also help loosen the turf and allow moisture to feed the roots of the grass once again. With the health of the turf restored you can then reseed the area with fresh grass seed to fill in the brown patch in your lawn.


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