How to Get Rid of Brown Patch Disease on Grass - Backyard Boss
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How to Get Rid of Brown Patch Disease on Grass

Hot and humid weather signals the peak of summer, which also means potential issues for your lawn. Rhizoctonia fungus causes Brown Patch disease and thrives in hot conditions. Daytime temperatures above 80 degrees Fahrenheit and overnight temperatures around 68 degrees Fahrenheit are the ideal conditions for it to spread. This disease attacks cool and warm grasses; the most common are tall fescue, bluegrass, ryegrass, and St. Augustine grass.

If you’ve noticed irregular circular patches of brown grass on your lawn, chances are it’s Brown Patch. On closer inspection, the patches will appear sunken in, and blades of grass will have light brown spots with a darker edge. In the early morning, the white strings of the fungus will be visible.

Overwatering, poor drainage, or poor aeration are some potential causes of Brown Patch disease. This article will walk you through the steps to get rid of Brown Patch disease as soon as you find it.

Materials You’ll Need: 

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  • Lawn aerator (rental/purchase)
  • Wheelbarrow
  • Shovel
  • Rake
  • One gallon hand pump sprayer (if needed)
  • Garden Sulfur (if needed)
  • Fungicide (if needed)
  • PPE (chemical resistant gloves, eye shield, respirator mask) (if needed)

Step One: Change How You Take Care of Your Lawn

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Before you rush out and buy chemicals and fancy tools, remember that adjusting your lawn care practices may be what solves your Brown Patch issues. Abide by these lawn watering rules and monitor your lawn progress:

  • Water your lawn less frequently and as early in the day as possible so the sun can dry out the soil.
  • Heavy, infrequent watering is superior to daily, shallow watering.
  • Sharpen lawn mower blades once a month. Dull blades can spread the fungus to other parts of the lawn.
  • Dispose of lawn clippings while Brown Patch Disease is visible to prevent fungus spread.
  • Cut grass higher than usual, around three and a half to four inches. Taller grass promotes health and new growth. 

Step Two: Let Your Lawn Breathe

close up plugs from lawn aeration
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Aeration may be the next best step if you know your lawn has poor drainage or is waterlogged. There are many lawn aerator options that will work depending on the size of your property and whether you prefer manual aeration or a machine. Aerators are also available to rent from most home stores. 

Whichever you choose, ensure the aerator removes a ‘core’ of grass. Ideally, your aerator should remove a cylinder of grass two to three inches deep, 1/2 inch in diameter, and about two to three inches apart. This spacing will ensure oxygen can access deep grass roots and will dry out and loosen compact soil. 

Lastly, after aeration, leave the plugs and trimmings on your lawn. You can break up dried plugs with a rake or lawnmower, and in a couple of weeks, they will disintegrate back into the yard, adding nutrients to the soil. 

Step Three: Give Back to Your Soil

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After aerating, you can add compounds back into the soil depending on the type of lawn.

For warm grasses like St. Augustine, compost is an excellent post-aeration addition to your soil. Compost can balance out soil structure and acts as a fertilizer, promoting healthy grass that can resist Brown Patch disease.

For grasses with clay soil, masonry sand is a lesser-known, fantastic addition to your lawn. This sand helps with water drainage and encourages healthier grass.

Overseeding your lawn is an excellent option for grasses with Brown Patch disease late in the season. Overseeding means spreading new grass seeds over the existing ones. It will help build up the areas the disease has compromised. However, when temperatures are extremely high, seeding isn’t recommended, so this option may be weather dependent.

Whichever top dressing you choose, compost, sand, or seed, these are best distributed by hand. You’ll need a wheelbarrow, shovel, and rake for distribution. 

First, fill the wheelbarrow with your compound of choice. Next, use the shovel to spread it over a given area. Lastly, use the rake to even out the spread. You should apply 1/4 – 1/2 inches of topsoil to allow the grass to grow through it. 

Step Four: Apply a Fungicide

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Fungicide should be the last step in repairing Brown Patch disease. If the previous three steps have not solved the issue, apply a fungicide only to affected areas of the lawn. It will stop the fungus from spreading, but affected areas will still look brown.

There are many fungicides on the market. Make sure the one you purchase is correct to treat Brown Patch disease. Garden Sulphur fungicide is also a good option for clay soil.

It’s necessary to take appropriate precautions when working with fungicide. It includes wearing long clothes to protect your skin, eyewear, a breathing mask, and chemical-resistant gloves.

The most consistent way to apply fungicide is with a powered sprayer. Refer to this video for the instructions on how to fill and use your powered sprayer. Once the sprayer is ready, apply the liquid evenly to any affected areas. Keep people and pets off the treated areas until they are fully dry.

Refer to the fungicide’s instructions for a second application. 

Let Your Lawn Do the Work!

With the proper knowledge, you can treat Brown Patch disease quickly. With the know-how to address soil or drainage issues, you can put your lawn back on a healthy track in a few steps. Although it will take time for areas affected by Brown Patch disease to recover, focusing on the health of your lawn will ensure that by next season it’ll be a thing of the past!

Let us know in the comments if this guide has been helpful and what you’ve done to combat Brown Patch disease on your lawn!