Home Improvement Expert Danny Lipford

How to Deal with Grass Fungal Diseases in Your Lawn

Irregular patches of fungal disease in centipede grass lawn.

Irregular patches of fungal disease in centipede grass lawn.

Lawn fungal diseases take on a variety of forms – from dead-looking brown patches to highly visible spots, threads, rings, or slimes. And once they strike your yard, grass fungal diseases can be difficult to treat.

Fortunately, the right lawn care practices can go a long way toward prevention and treatment; and in severe cases, a fungicide can help eradicate the spores to keep it from spreading. Here are some tips for preventing and treating fungal diseases in your lawn.

Mowing grass in yard with lawn mower

Mowing your grass too low can encourage fungal disease.

Causes of Lawn Fungal Disease

Your lawn is naturally full of fungi and spores, some harmless and some problematic, but the right (or wrong) conditions can cause grass fungus to erupt into a harmful disease. The most common causes of a lawn fungal disease are:

  • Drought
  • Improper mowing (especially mowing too low)
  • Compacted soil
  • Overwatering
  • Too much fertilizer (or using the wrong kind)
  • Wrong grass type for your yard
  • Weather conditions (particularly temperature and humidity)

How To Identify Lawn Fungal Diseases

Signs that your lawn may have a fungal disease include:

Brown patch of dead grass in lawn

Brown patch of dead grass in lawn.

  • White, yellow, or brown patches or rings that grow in diameter.
  • Thin patches of frayed, distorted, or discolored grass blades.
  • Gray, black, red, orange, or purple spots on blades or stems.
  • Gray, black, or pink powdery or threadlike coatings on and around grass blades.
  • Areas of darkened, wet-looking, slimy, or greasy-looking grass.

Common Lawn Fungal Diseases

There are quite a few fungal diseases that can impact lawns, but they’re usually pretty specialized, targeting specific lawn types, at certain times of year, under certain conditions. For example:

  • Brown patch strikes during hot, humid weather.
  • Fusarium blight prefers hot, drought conditions.
  • Dollar spot tends to spring up when nights are cool and dew is heavy.

Before treating your lawn, it’s important to identify not only whether your lawn indeed has a fungal disease, but to identify the fungus itself. All fungicides aren’t the same, and some diseases can be easily treated by making changes in your lawn care.

Knowing your grass type and recent weather conditions can make it easier to narrow down, but you may need help in figuring out exactly what’s going on. Your local cooperative extension center is your best resource for determining which diseases are most common in your area, or you can take a small baggie of the infected grass to your local garden center for help.

Using a fertilizer spreader to apply antifungal treatment to lawn

Applying an antifungal treatment may be necessary to treat severe cases.

How To Prevent and Treat Lawn Fungal Diseases

A simple change in your lawn care practices may be enough to prevent or eradicate lawn fungal disease. At other times nature may deliver a soggy spring or summer heat wave that just can’t be helped. Stressed or unhealthy lawns are much more likely to develop disease; so the better you care for your lawn, the better the grass will be able to handle the natural conditions in your area.

Follow these steps to help take control of fungal diseases in your lawn:

  • Soil Test: Conducting a soil test can not only identify nutrient deficiencies that lead to stressed lawns and disease but sometimes can be used to diagnose the disease itself. Check with your local cooperative extension office for more information.
  • Aerate: Loosen soil by aerating your lawn every year or two.
  • Top-Dress: Apply and rake in a layer of rich, organic top-dressing to improve the soil, increase drainage, and help combat disease.
  • Dethatch: Remove thick buildups of thatch in your lawn to allow the soil to breathe.
  • Sprinkler watering lawn.

    Improper watering can lead to lawn fungus.

  • Grass Type: Rather than fighting nature to have an exotic lawn, choose a grass type that’s suited for your climate, soil, and light conditions. Well chosen lawns are stronger and able to fight off the normal fungal spores native to the area.
  • Go Organic: Synthetic fertilizers, pesticides, and other lawn chemicals can upset your lawn’s ecosystem – allowing disease organisms to grow unchecked. Using organic materials helps keep your lawn in balance.
  • Fertilizing: Both over and under fertilizing can promote some fungal diseases. Choose organic, slow-release fertilizers for your lawn, and apply them exactly as instructed. Avoid excess nitrogen, which creates a fast green lawn with very poor defenses.
  • Watering: Water early in the morning, to allow the grass blades to dry during the day. Give your lawn one inch of water per week, and use a rain gauge to keep track. Water deeply, but less frequently, to encourage stronger roots and to allow the water to absorb properly.
  • Mowing: Follow good mowing practices, including keeping the mower blades sharp and mowing your lawn to the correct height. Scalped lawns are much more vulnerable to fungal disease. If your lawn has diseased patches, be sure to wash and disinfect the underside of your mower after each use.
  • F-Stop Antifungal lawn treatment

    Antifungal grass treatment for lawn.

  • Air Circulation: Many lawn fungi develop under moist, still conditions. Thin out trees and shrubs to allow air to circulate all over your lawn, and plant shade-tolerant grasses under trees.
  • Snow: Avoid walking on or compacting snow in your yard during the winter, since heavy snow layers can breed snow molds that emerge in spring.
  • Go Natural: If certain areas of your lawn are prone to fungal disease due to conditions you can’t change, consider naturalizing the area with groundcovers or flower beds that will be better suited to those conditions.
  • Organic Treatment: Applying organic treatments – such as neem oil, compost tea, or a weak baking soda solution – can help with small patches of fungus.
  • Fungicides: If all else fails, look for a fungicide (preferably organic) that’s rated specifically for your lawn disease. Fungicides won’t help your grass regrow, but they’ll get the fungal spores in check so that your improved lawn care practices can take effect.

Further Information

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11 Comments on “How to Deal with Grass Fungal Diseases in Your Lawn”

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  1. ron larson Says:
    June 10th, 2012 at 3:50 pm

    seems to provide nothing about revitalizing a lawn the year after after the fungus has occurred, eg there was fungus here last year, but how do we deal with the results this year…re seed? refertlize etc as well as the mowing tips you provide.

  2. Peggy Says:
    August 21st, 2014 at 10:45 am

    I was wondering can a fungus also be transmitted from your Gardner blades on his lawn mower From one lawn to another Any other disease be spread this way and how would you prevent this. We had new sod beautiful after about 5 months we had a fungus he has been treating it and it only seems to be getting worse. About 60% of our lawn looks gone? How do we know when the fungus is gone and we can re-seed?

    Thank you. From your article it looks like I do need to bring by grass/soil up for testing.


  3. brian simpkins Says:
    September 1st, 2014 at 11:12 pm

    one side of my lawn is growing great. however, the other side is not growing as thick. what would you suggest???

  4. Patrick Says:
    September 8th, 2014 at 5:31 pm

    What is the best prodcut for treating fungus in the yard. The grass I have 31 Fescue. I reseeded 2 years ago. My original grass was Falcon Fescue and Southern Choice. Cool season grasses. I need a good product to apply. Please advise – do I need a commercial grade or can find something at local Home Depot / Lowes?

  5. Madelyn Markham Says:
    September 21st, 2014 at 12:35 pm

    How would I wash and disinfect my lawnmower when it is electric? And what would I use to disinfect it with?

  6. B. Apelt Says:
    October 15th, 2014 at 2:07 am

    I have a well known lawn service and they say you never get rid of brown patch or fungus you can only try and control it with their chemicals. Honestly I have it every year when the hot weather hits and the lawn looks awful. Next year I am not paying these people. I want a good answer on how to GET RID of fungus. I will do whatever it takes except move. I tried fungus control from Home Depot..didn’t work. There must be something out there that will get rid of it and not just control it.

  7. Darryl Says:
    October 26th, 2014 at 9:53 am

    My lawn has large sections that are just barren and these large purple mushrooms that emit this dust red powdery substance comes off of them have tried turning the lawn and reseeding nOTHING Works

  8. Peg Atkins Says:
    November 11th, 2014 at 5:08 am

    After complaining to my lawn service for the past three or four years they finally decided to test the soil for a fungus. They applied fungicide on Bermuda grass 11/10.
    Is this the correct time of the year for this treatment?

  9. Dilly Says:
    November 21st, 2014 at 7:06 am

    There is no cure. All you can do is treat it or apply fungicide prior to the time of year when it usually begins. Once you have it (brown patch) you have it forever Some years conditions will not be favorable so the lawn will remain healthy. As for cleaning the mower, some lawn maintenance companies say to use bleach(you can never reach every crevice and if you try this, don’t forget the tires) but the best medicine is to avoid mowing the areas when the fungus is active. The outside borders will be bright yellow and if you pull on the grass blades they will come out readily. Brown patch doesn’t usually kill your lawn (at least not St. Augustine-like grass with underground runners), it is just unsightly. Once the temp gets below 60 degrees, you can rake out the dead grass.

  10. Damien Casey Says:
    December 15th, 2014 at 2:42 am

    Just laid sir Walter buffalo 5 weeks ago due to the unevenness off the grass I top dressed it with white washed sand. Some spots up to 40mm now I know to thick. Iam having green algae spits coming through the sand how do I rectify

  11. Pat Neese Says:
    March 16th, 2015 at 6:51 pm

    I’m in Michigan, and our snow is gone as of yesterday. I thought there was still a little left all over my front yard but I looked at it today, being it was 60 degrees and still white all over. Is it a fungus? Will this go away? I’ve never had this before and I don’t know what to do. I plan on raking the yard likely just to clean it up some, but should I be putting something on this or wait and see what happens? Thank you.

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