How to Get Rid of Lawn Fungus: Identify, Treat, and Prevent 6 Common Lawn Diseases
Table of Contents
- What Does Lawn Fungus Look Like?
- Is It Fungus or Something Else?
- What Causes Lawn Fungus?
- How to Identify the 6 Most Common Lawn Fungi
- How Do You Get Rid of Lawn Fungus?
- Can You Treat Lawn Fungus Naturally?
- Which Lawn Fungicide Should You Use?
- When Should You Apply Fungicide to Your Lawn?
- How to Prevent Lawn Fungus
- Lawn Fungus FAQs
- Let The Turf Wars Begin!
Quick Answer: To get rid of lawn fungus, first identify which disease you've got, because the fix depends on it. Then correct the conditions that let it in: water early in the morning instead of at night, mow at the right height with a sharp blade, feed the lawn the right amount of nitrogen, and relieve thatch and compaction. Mild cases of diseases like red thread and powdery mildew often clear up on their own once conditions change. For serious or spreading outbreaks of brown patch, dollar spot, snow mold, or necrotic ring spot, apply a lawn fungicide labeled for that disease,and repeat according to the label's schedule.
Your lawn is a point of pride. Unfortunately, it's also prime real estate for fungi. Fungal spores are already sitting in your soil and thatch, or they blow in on the wind, and most of the time they're harmless. It's when the weather and your lawn care tip things in their favor that you get a full-blown turf war.
The good news? Once you know who you're fighting, most of these battles are winnable.
What Does Lawn Fungus Look Like?
Lawn fungus usually shows up as brown, tan, yellow, or straw-colored patches, spots, or rings that appear suddenly and spread. Look more closely, and you may see cobweb-like growth in the morning dew, lesions on the grass blades, a white powdery coating, or pinkish-red threads.
Here's a quick way to narrow it down:
| Disease | What it looks like | When it shows up | Grasses most at risk | Usually needs fungicide? |
|---|---|---|---|---|
| Brown patch | Circular brown patches from a few inches to several feet, sometimes with a darker "smoke ring" edge or a green center | Hot, humid summer weather with warm nights | Tall fescue, St. Augustine, Perennial Ryegrass, Kentucky Bluegrass | Often, in bad years |
| Dollar spot | Small straw-colored spots that merge into larger patches; blades have bleached lesions with reddish-brown edges | Late spring to fall, warm days and cool, dewy nights | Kentucky Bluegrass, Perennial Ryegrass, Fine Fescue, Bermuda, Zzoysia | Sometimes |
| Powdery mildew | White to gray dusty coating on the blades, like a sprinkle of flour | Late summer and fall, in shade | Kentucky Bluegrass in shade | Rarely |
| Red thread | Pink or reddish patches with tiny red threads poking out of bleached blades | Cool, wet spells in spring and fall | Perennial Ryegrass, Fine Fescue, Kentucky Bluegrass | Rarely |
| Snow mold | Matted, straw-colored circles with gray or pinkish fungal growth as snow melts | Late winter and early spring | Cool-season lawns under long snow cover | Prevention only, in problem areas |
| Necrotic ring spot | Rings or "frog-eye" patches of dead grass with green grass in the middle | Shows in late spring to fall; infects in spring | Kentucky Bluegrass, Fine Fescue | Often, if it keeps returning. |
Is It Fungus or Something Else?
Before you reach for a fungicide, rule out the look-alikes. Dog urine spots, grub damage, drought stress, fertilizer burn, and frost damage can all mimic fungus. Fungus usually comes with a clue: a defined ring or patch shape, lesions on individual blades, or visible fungal growth. If you're seeing brown grass after a cold snap, read Frost Damage vs. Lawn Fungus: How to Tell the Difference first.
Golf Course Lawn Tip: Take your coffee out to the lawn at sunrise. Many fungi, including brown patch and dollar spot, show their cobwebby growth (mycelium) in the morning dew and then vanish once the grass dries. Five minutes at dawn can save you a misdiagnosis.
What Causes Lawn Fungus?
Lawn fungus is caused by fungi that live in nearly every lawn, but it only becomes a disease when three things line up: a susceptible grass, an active fungus, and the right weather. Turf folks call this the disease triangle. You can't control the weather, but you can control a lot of the rest.
The usual culprits that tip the balance:
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Grass staying wet too long. Evening watering and heavy dew keep blades wet overnight, which is exactly what most lawn fungi want.
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The wrong amount of nitrogen. Too much feeds brown patch. Too little invites dollar spot and red thread.
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Mowing too short or with a dull blade. Scalped or shredded grass is stressed and wounded grass.
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Thick thatch and compacted soil. Both hold moisture at the surface and starve roots of air.
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Shade and poor airflow. Damp, still corners of the yard are fungus hot spots.
How to Identify the 6 Most Common Lawn Fungi
Brown Patch
Brown patch, caused by the fungus Rhizoctonia solani, is one of the most common summer lawn diseases in the U.S. It's a hot-weather problem, especially when humid nights leave the grass wet until morning.
How to spot it: Roughly circular brown patches from a few inches to several feet across, which can appear almost overnight. Sometimes the patch has a green center, making a doughnut shape, and on dewy mornings, you may see a dark, smoky ring or fluffy webbing at the edge. Individual blades show irregular tan lesions with darker borders.
For a deeper dive, see How to Get Rid of Brown Patch Fungus on Your Lawn.
Dollar Spot
Dollar spot is caused by Clarireedia jacksonii (you may still see its old name, Sclerotinia homoeocarpa). It earned its name on golf greens, where it makes spots about the size of a silver dollar. On a home lawn mowed higher, the spots are bigger and often merge into larger patches.
How to spot it: Small, sunken, straw-colored spots. Check the blades: dollar spot leaves bleached tan lesions with reddish-brown borders, often across the width of the blade. On dewy mornings, you may see white, cottony growth. Lawns low in nitrogen are especially prone to it.
More on this one in How to Control Dollar Spot.
Powdery Mildew
Powdery mildew is caused by Blumeria graminis (formerly Erysiphe graminis). It looks like someone dusted your grass with flour, and you can rub the white coating off with your finger.
How to spot it: A white to gray powdery coating on the upper side of the blades, worst in shady spots. Infected blades may yellow over time. It loves shade, poor air circulation, high humidity, and cool temperatures, and Kentucky Bluegrass growing in shade is its favorite target. It rarely kills grass, but it can thin a shady lawn over the course of a season.
Red Thread
Red thread is caused by Laetisaria fuciformis. It's one of the easiest lawn diseases to identify and one of the least serious.
How to spot it: Pinkish or reddish patches of bleached grass. Look closely, and you'll see tiny red, antler-like threads growing out of the tips of the blades. It's most common during long, cool, wet spells in spring and fall, and it's a classic sign of a lawn that's short on nitrogen. Because it attacks the leaves and not the roots, most lawns recover within a few weeks.
More detail here: Red Thread Disease Control.
Snow Mold
There are actually two snow molds. Gray snow mold is caused by Typhula species, and pink snow mold by Microdochium nivale. Both show up as the snow melts in late winter and early spring, especially where snow sat on the ground that never froze solid.
How to spot it: Circular patches of matted, straw-colored grass with gray or pinkish fungal growth around the edges. Gray snow mold patches can run from a few inches to a few feet across and may have tiny, pinhead-sized dark bodies (sclerotia) on the blades. Pink snow mold patches are usually smaller, under about 6 inches, and can turn pinkish in the light.
The good news is that most lawns recover from snow mold on their own. If yours gets hit hard every year, read Preparing Your Lawn for Winter Snow Mold and Managing Winter Lawn Disease.
Necrotic Ring Spot
Necrotic ring spot is caused by Ophiosphaerella korrae, a soil-borne fungus that attacks the roots. It mainly affects established Kentucky Bluegrass lawns, along with Fine Fescues, and it doesn’t usually appear until a lawn is a few years old.
How to spot it: Light-green patches a few inches across that fade to straw-colored rings, often 1 to 3 feet wide, with healthy-looking grass in the middle (that "frog-eye" look). The same patches tend to come back year after year. Here's the tricky part: the fungus infects the roots in spring, but you often won't see the damage until later, when heat or drought stresses the weakened grass. It's very hard to tell apart from summer patch without a lab test.
Golf Course Lawn Tip: Not sure what you're looking at? Most state extension services run a plant diagnostic clinic that will identify a lawn disease from a sample for a small fee. Dig up a 4-to-6-inch plug from the edge of a patch, where sick grass meets healthy grass, and send it in. It's a lot cheaper than buying the wrong fungicide.
Related reading: Your Ultimate Winter Lawn-Care Guide
How Do You Get Rid of Lawn Fungus?
You get rid of lawn fungus in two moves: fix the conditions that let it in, then treat the disease directly if it's serious or spreading. Fungicides stop fungus from spreading and protect healthy grass. They won't bring dead grass back, so expect a couple of weeks or more for the lawn to fill in.
Here's the plan for each disease.
Brown Patch Treatment
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Water in the early morning only, and check for brown patch before you water, as extra watering can speed the fungus up.
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Go easy on nitrogen in summer. Heavy feeding during hot weather is brown patch's best friend.
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Mow tall and sharp. For tall fescue, keep it at 3 inches or higher.
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Use a fungicide for active or recurring outbreaks. Headway® G or Pillar® SC are both labeled for brown patch (more on choosing between them below).
Dollar Spot Treatment
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Feed the lawn properly. Low-nitrogen turf is more susceptible and recovers more slowly. A balanced fertilizer on your grass type's normal schedule helps the lawn grow out of it.
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Cut leaf wetness. Water deeply and infrequently in the early morning, never in the evening.
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Don't spread it. Avoid mowing or walking on wet, infected grass, and bag cuttings from affected areas.
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Use a fungicide if it keeps spreading. Fungicides are often unnecessary on home lawns, but Headway® G or Pillar® SC are both labeled for dollar spot if you need one.
If your soil is hungry, Lebanon Country Club Complete 14-7-14 Fertilizer is a balanced feed that covers the basics.
Powdery Mildew Treatment
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Let in light and air. Prune overhanging trees to improve airflow.
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Switch grass types in deep shade. Fine fescues and tall fescue are much more resistant than Kentucky Bluegrass.
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Don't overfeed shady areas. Grass in shade needs less nitrogen than grass in full sun.
Red Thread Treatment
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Apply nitrogen. This is usually all it takes. Adequate nitrogen usually reduces red thread, and it's rarely severe enough to need a fungicide on a home lawn.
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Improve drainage with core aeration, and keep thatch under control.
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Bag your cuttings while it's active, so you're not spreading the threads around the yard.
Snow Mold Treatment
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Rake matted patches gently in spring so they dry out, and new growth can come through. Overseed any areas that don't recover.
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Prevent it next winter. I recommend mowing at the normal height right through fall, avoiding heavy late-fall nitrogen, keeping thatch under ½ inch, and raking up leaves before the snow comes.
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Use a preventive fungicide only if snow mold hits the same areas hard every year. It has to go down in late fall (typically October or November, depending on where you live) before the first lasting snow. Once the snow melts and you can see it, it's too late to spray for this season. Headway® G or Pillar® SC are both labeled for gray and pink snow mold.
Necrotic Ring Spot Treatment
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Time it right. Necrotic ring spot is a game of prevention. Apply a fungicide in fall, followed by another in spring, once the soil is at 2 inches deep reaches around 68 to 70°F, and water it in well so it reaches the root zone.
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Check your pH. Necrotic ring spot is worse in alkaline soil. Test first, and if your pH is high, sulfur amendments can help.
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Relieve compaction and thatch with core aeration, water deeply rather than often, and avoid heavy, unbalanced feeding.
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Overseed with resistant varieties if the rings keep coming back. Blending in perennial ryegrass or tall fescue helps.
Don't guess your pH. A MySoil Test Kit tells you your pH and nutrient levels so you know whether sulfur is the right move.
Golf Course Lawn Tip: Fungus hitches rides. Mow the infected areas last, bag those cuttings, and hose off your mower deck and shoes before moving to healthy grass or your neighbor's yard.
Related reading: The Most Effective Fungicides to Use on Your Lawn
Can You Treat Lawn Fungus Naturally?
Yes, and for mild cases, natural fixes are usually all you need. The most effective natural treatment for lawn fungus isn't a spray at all. It's changing the conditions that let the fungus thrive: watering in the morning, feeding the right amount, mowing higher with a sharp blade, aerating, dethatching, and letting in more light. Red thread, powdery mildew, and mild dollar spot often fade on their own once you do.
You'll see homemade sprays, like milk or baking soda mixed with water, recommended all over the internet. To be straight with you, the research behind them comes from vegetable crops in greenhouses, not lawns, and baking soda adds sodium to your soil. If you want to experiment, try a small patch first and don't count on it for a serious outbreak.
Healthy soil biology also helps grass bounce back once the fungus is under control. CarbonizPN-G™ is a granular compost and biochar blend that helps improve soil structure and water-holding, so it's a good partner when you're nursing a lawn back after a disease.
Which Lawn Fungicide Should You Use?
The best lawn fungicide is one that's labeled for the disease you've identified and for your grass type. Both of the fungicides we stock for homeowners cover all 6 diseases in this guide. The real choice is granular or liquid.
| Product | Type | Active ingredients | Coverage | Good fit for |
|---|---|---|---|---|
| Headway® G | Granular | Azoxystrobin + propiconazole | 8,500 to 15,000 sq ft per 30 lb bag, depending on the disease | Homeowners with a broadcast spreader who want a simple granular application |
| Pillar® SC | Liquid | Pyraclostrobin + triticonazole | Up to 43,500 sq ft per 43.5 oz bottle at 1 oz per 1,000 sq ft | Larger lawns, or anyone already set up with a sprayer |
| Caravan® G | Granular | Azoxystrobin + thiamethoxam (insecticide) | 10,700 to 15,000 sq ft per 30 lb bag, depending on the target | Lawns that need summer grub protection and brown patch prevention in one pass |
Headway® G: The Easy Granular Option
Headway® G combines two fungicides from different chemical families: azoxystrobin and propiconazole. You spread it with a broadcast spreader, then water it in with about ¼ inch of irrigation or rain within 48 hours. Its label covers brown patch, dollar spot, necrotic ring spot, gray and pink snow mold, red thread, powdery mildew and plenty more, and it's labeled for both cool-season and warm-season lawns. For an active outbreak, plan on a follow-up application; check the label for the interval for your disease.
Pillar® SC: The Liquid Option for Bigger Lawns
Pillar® SC is a liquid fungicide that pairs pyraclostrobin and triticonazole, and it's labeled for 26 turf diseases, including all 6 in this guide. It goes on at 1 oz per 1,000 sq ft, so one bottle covers a big lawn. It gives up to 28 days of protection, and for disease that's already active, a second application 14 to 21 days after the first is recommended. Water it in with about ¼ inch afterward.
For accurate spraying, a proper backpack sprayer gives you far more control than a hose-end sprayer.
Caravan® G: Fungus and Grubs in One
If you're already planning a summer grub treatment and brown patch is a regular visitor, Caravan® G handles both. It's labeled for brown patch, large patch, necrotic ring spot and fairy ring, plus white grubs, chinch bugs and sod webworms. It's best applied between May and July. If you need a follow-up for an active fungal outbreak, the Caravan® G product page recommends switching to Headway® G about 28 days later rather than reapplying Caravan® G.
When Should You Apply Fungicide to Your Lawn?
Apply fungicide preventively, just before the weather that triggers your disease, or at the first sign of an active outbreak. Fungicides work best as a shield. Waiting until half the lawn is brown means you're protecting what's left, not saving what's gone.
| Disease | Best time to apply | Notes |
|---|---|---|
| Snow mold | Late fall (October to November), before lasting snow. | Prevention only. Too late once you see it. |
| Necrotic ring spot | Fall, then spring when soil at 2 inches reaches ~68 to 70°F | Water-in well so it reaches the roots. |
| Brown patch | Late spring to early summer, before hot, humid nights | Repeat on the label interval through the summer if needed. |
| Dollar spot | Late spring, then as needed through fall | Fix nitrogen first; you may not need it. |
| Red thread / powdery mildew | Rarely needed | Cultural fixes first. |
Before you apply any fungicide:
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Read the label. It's the legal guide to using the product, and it overrides anything here, including rates, intervals, and the maximum number of applications per year.
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Apply fertilizer first. If you're feeding the same day, put down fertilizer and granular products before liquids.
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Water it in with about ¼ inch of water, as both Headway G and Pillar SC call for.
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Keep kids and pets off the treated area until it's dry, or for as long as the label says.
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Give it time. Fungicides stop the spread quickly, but new growth takes a couple of weeks or more to fill the damaged areas.
How to Prevent Lawn Fungus
Prevention beats cure every time. Some diseases, like necrotic ring spot, have no quick fix once they're established, so the real win is a lawn that doesn't give fungus an opening.
Water Early, Deeply and Less Often
Aim for about 1 inch of water a week, including rain, split into two or three deep waterings. Water early in the morning, ideally between 4 and 6 a.m., so the grass dries during the day. Evening watering leaves blades wet all night, and that's when fungus does its best work.
Mow at the Right Height With a Sharp Blade
A dull blade shreds grass, and every ragged tip is an open door for fungus. Sharpen your blade a couple of times a season. Then mow at the right height for your grass:
| Grass type | Mowing height |
|---|---|
| Tall Fescue, Kentucky Bluegrass, Perennial Ryegrass, Fine Fescue | 3 to 4 inches |
| Bermudagrass | 0.5 to 1.5 inches (reel mower), 1 to 2 inches (rotary) |
| Zoysia | 1 to 2 inches |
| Centipede | 1.5 to 2 inches |
| St. Augustine | 2.5 to 3 inches or higher |
Cutting too short stresses the grass and makes almost every disease on this list worse. Never take off more than a third of the blade in one mow.
Dethatch When Thatch Gets Thick
A thin layer of thatch is fine. Once it's more than about ½ inch thick, it holds moisture at the surface and gives fungi a cozy place to overwinter. Dethatch with a rake or a scarifier when the grass is actively growing.
Core Aerate Once a Year
Core aeration pulls plugs of soil, usually 2 to 4 inches long and about ½ inch wide, out of the lawn. That relieves compaction and lets water, air and nutrients reach the roots. Do it at least once a year: fall for cool-season grass, late spring to early summer for warm-season grass.
Feed for Balance
Follow a fertilizer program that matches your grass type and your soil test results. Not too much (brown patch), not too little (dollar spot and red thread). Our lawn fertilization program calculator can help you plan.
Golf Course Lawn Tip: If the same patch of lawn gets fungus every year, look up. Shade, poor airflow, and a low spot that stays soggy are almost always behind repeat offenders. Fix the spot, not just the symptom. Our guide Why Lawn Problems Come Back Year After Year digs into this.
Lawn Fungus FAQs
Will lawn fungus go away on its own?
Some will. Red thread, powdery mildew, and mild dollar spot often clear up once the weather changes, and you fix the watering, mowing, and feeding. Brown patch, snow mold, and necrotic ring spot can cause lasting damage, so it's worth acting quickly if they're spreading or returning every year.
How long does it take for lawn fungicide to work?
A fungicide starts protecting healthy grass soon after it's watered in, but damaged areas take a couple of weeks or more to fill back in with new growth. For active outbreaks, a second application on the label's interval is often needed.
Should I water after applying fungicide?
For Headway G and Pillar SC, yes. Both call for about ¼ inch of water after application to move the product down to where it's needed. Always follow the label for the product you're using.
Can I fertilize a lawn that has fungus?
It depends on the disease. Dollar spot and red thread are signs your lawn is short on nitrogen, so feeding helps. Brown patch is the opposite: heavy nitrogen in hot weather makes it worse. Identify the disease first.
Is lawn fungus harmful to pets or people?
The common lawn diseases in this guide attack grass, not people or pets. The bigger safety question is the treatment: keep kids and pets off a treated lawn until it's dry, or for as long as the product label says.
Can lawn fungus spread to my flowers and plants?
Most lawn fungi are specific to turfgrass. Powdery mildew on your roses, for example, is a different fungus from the one on your grass. It's still smart to clean tools and mower decks between areas.
Should I bag my grass cuttings if I have lawn fungus?
Yes, while the disease is active. Cuttings can carry fungus to healthy parts of the lawn, especially with dollar spot and red thread. Go back to mulching once it's under control.
Let The Turf Wars Begin!
Lawn fungus is a sign your lawn's conditions have tipped in the fungi's favor. Identify the disease first, then fix the watering, mowing, feeding, and thatch that let it in. For serious or recurring outbreaks, a fungicide labeled for your disease, applied at the right time and watered in, will protect your grass while it recovers.
Ready to fight back? Browse our insecticides and fungicides to find the right match for your lawn. And if you want to see these products in action before you buy, check out our videos on the Golf Course Lawn YouTube channel.
Originally published on October 5, 2023
Ron Henry
Ron Henry is the founder of Golf Course Lawn, which is dedicated to helping homeowners achieve golf course-quality lawns. He holds a certificate in Sports Turfgrass Management from the University of Georgia. With expert knowledge in turf care, fertilization, and weed control, he shares practical tips and product recommendations to create lush, healthy lawns.