How To Treat Fungal Disease in Your Lawn

If you’ve noticed unsightly patches of brown grass in your usually bright green lawn, you might be seeing a fungal turfgrass infection.

Ancient societies believed fungus damage to be a punishment from the gods, as infection would sweep through farms and ruin crops. While fungal grass infections are still incredibly frustrating for the modern homeowner, we know that they’re treatable and often preventable. 

This article will focus on fungi that infect turfgrass, leaving your lawn withered and weak. We’ll discuss treatment and prevention methods so you can get back to having the best lawn on your block.

What is Lawn Fungus? 

Fungi are a family of organisms that survive by breaking down organic matter. In this way, fungus is often beneficial; humans not only consume fungus as food but also use it in medicinal and fermentation processes.

However, fungus can be harmful, too. The parasitic nature of the organism leads it to damage home gardens and lawns. 

Lawn fungus can leave turfgrass spotty and weak as the tiny organisms absorb nutrients from the grass. Luckily, many treatment methods and products are available to weed out fungal infections before they take over your whole yard. 

The following sections will provide tips for identifying and handling common types of fungus.

How to Identify and Treat Common Lawn Diseases

Powdery Mildew

What Is It?

Powdery mildew is a common plant disease caused by the fungus Erysiphe graminis. This infection is most likely to develop in areas of high temperatures, poor air drainage, humid weather, and low light intensity. 

The fungus produces spores that sit on infected leaves and exhibit a powdery appearance. At first, a white dusting appears on the tips of infected blades of grass. As the mildew reproduces, turfgrass may turn pale and withered.

How to Prevent and Treat It

The Ohio State University Ohioline Extension provides the following tips for treating powdery mildew infection in turfgrass:

• Research grass varieties that are resistant to powdery mildew.
• Increase your lawn’s exposure to sunlight by pruning back shade trees and shrubs.
• Improve your turf’s air circulation by thinning out nearby trees and shrubs.
• Adjust your irrigation schedule to ensure your lawn isn’t staying wet enough to encourage mildew growth.
• Apply preventive fungicide regularly to protect your property from mildew infection.

Snow Mold 

What Is It?

Snow mold is caused by a fungus called Typhula incarnata that is tolerant to the cold. These fungi can multiply at freezing temperatures, which leaves turfgrass under snow cover especially vulnerable.

Your lawn may be susceptible to gray or speckled snow mold if your grass is tall and becomes matted down by heavy snow or ice. Infection may worsen in the early spring when the snow melts and the lawn is wet from thawing.

If your lawn is infected with gray snow mold, you’ll see circular gray areas throughout the turf. Matted areas may develop patches of black mold called sclerotia.

Typhula incarnata typically enters a dormant phase as turf dries out through spring and fall. However, you may still see “scars” leftover from the damage.

How to Prevent and Treat It

If you live in an area with heavy snowfall and cold winters, prevention is the best method of snow mold control. 

The University of Illinois College of Agricultural, Consumer, and Environmental Sciences provides the following tips for preventing snow mold infection:

• Avoid using nitrogen fertilizers in the six weeks leading up to the first frost or snowfall.
• Avoid heavy use of lime treatments.
• Aerate and dethatch your lawn to prevent thatch buildup.
• Install snow fences to prevent accumulation.
• Apply fungicide to your lawn before the first heavy snow of the season.
• Repair damaged areas in the spring by dethatching, reseeding, and overseeding.
• Prevent mold growth by ensuring your lawn has proper drainage and air circulation.

Necrotic Ring Spot

What Is It?

Necrotic ring spot (NRS) is caused by a fungus called Ophiosphaerella korrae. This fungus mainly affects cool-season grasses like Kentucky bluegrass.

According to the Utah State University Turf Pests guide, ring spots can be hard to diagnose because their symptoms resemble other common turf issues. Ophiosphaerella korrae kills the grass’s roots, leaving yellow patches in an otherwise healthy lawn. Unfortunately, improper mowing and imbalanced soil moisture can leave similar irregular patches in your grass.

You can determine if ring spots affect your lawn by noting when symptoms appear. NRS fungus typically infects turf during early spring’s cool, wet weather. Symptoms may lessen during dry months but could be triggered again by the stress of drought.

If you’re still unsure of your turf’s ailment, you can send a soil sample to a local soil testing lab. Soil testing can help you determine any infections present in your lawn, as well as pH levels and nutrient deficiencies.

How to Prevent and Treat It

Light, steady watering can help your grass heal from necrotic ring spot infection. Light watering in hot weather conditions can reduce your lawn’s heat stress and begin the recovery process. Maintaining a well-balanced fertilization and aeration program will also give your yard the boost it needs to heal.

Aeration and slow-release fertilization allow for better nutrient absorption, removing stress from your already infected turf.

You can prevent the spread of NRS by cleaning your gardening equipment between uses. O. korrae can spread like any germ, so proper sanitation of tools like mower blades, rakes, and shovels is essential. You can also apply preventative fungicide in the early spring to ward off ring spots caused by wet conditions.

Fairy Ring Disease

What Is It?

Fairy ring disease is caused by grass fungi that feed on dead plant matter. The fungus releases nitrogen as it consumes decaying plants, resulting in brown patches or dark green rings in the turf. 

Some fairy ring fungi form a hydrophobic layer in the soil that keeps water from reaching plants’ roots. These fairy rings produce brown spots or unusually dark grass.

How to Prevent and Treat It

Fairy ring fungi spread to new sites in the air or when infected soil is transported to a new area. For this reason, it can be challenging to prevent the disease altogether. 

However, you can take a few preventative measures to decrease your lawn’s susceptibility to this pesky fungus. The Texas A&M AgriLife program offers the following tips to control and prevent fairy rings:

• Dethatch your yard to remove dead grass.
• Aerate your lawn to allow air circulation and drainage.
• Topdress your lawn by adding a thin layer of sand to the turf.
• Add nitrogen-rich fertilizer to mask symptoms caused by dark green fairy rings.
• Use a wetting agent on drought-symptom fairy rings to help water move through the soil.
• Frequently water the areas damaged by hydrophobic fungi.

Red Thread

What Is It?

Red thread disease is caused by a fungus called Laetisaria fuciformis. At a glance, red thread looks like round patches of pink grass amongst green, healthy turf. You can distinguish red thread up close by identifying spiky pink structures coating the tips of infected grass blades. 

Red thread most commonly appears during the spring and fall on Kentucky bluegrass, tall fescue, and perennial ryegrass. Lawns with poor nutrition and slow growth are the most vulnerable to infection.

How to Prevent and Treat It

Luckily, red thread doesn’t infect the root systems of grass, so symptoms are mainly cosmetic. The primary method to prevent and treat red thread infestation is to ensure your lawn can grow steadily with proper nourishment. You can do so by following a fertilization and watering schedule suited for your specific region. 

You should avoid watering your lawn in the late afternoon, as this will prolong the time water is sitting on your grass, inviting infection.

Otherwise, red thread disease is relatively cosmetic and will heal on its own throughout the turf’s life cycle. 

How to Treat Lawn Disease

You can treat lawn fungal disease by hiring a lawn care service or taking a DIY approach. You can also choose a chemical fungicide or try out an all-natural option. 

Any of these methods can work, but some are more costly and time-consuming than others. To select the best treatment option for you, determine if you’d rather pay more for a pro to diagnose and treat the issue or if you don’t mind doing the research and manual labor yourself. 

The next couple of sections will touch on some lawn disease treatment methods and how they can get your grass back in tip-top shape.

Using Fungicide to Treat Grass Fungus

Fungicide is a type of pesticide that kills fungi living on plants. It can be used for the prevention and treatment of lawn diseases.

If your lawn shows symptoms of infection and it’s too late for preventative measures, applying fungicide to your turfgrass may be an effective treatment method.

Home Remedies for Lawn Disease Treatment

Below are some home remedies for fungus control. These methods are meant to be used on smaller areas of infected turf or as preventive measures. Unfortunately, chemical fungicides may be necessary if your lawn is severely affected by fungus.

Compost Tea

Compost tea is a liquid version of compost made from water and microbial matter. The liquid is brewed in a machine to multiply beneficial bacteria and create a nutritious turfgrass treatment. 

Compost tea is best used as a preventive turf treatment because it adds good fungi to the soil to aid in nutrient uptake, keeping your lawn healthy and strong. The beneficial bacteria also build soil structure to help reduce compaction that can lead to fungal infection.

Neem Oil

If you’d prefer to go the all-natural route and avoid spraying chemicals on your lawn, you can buy a neem oil spray to fight fungus on your turf.

Neem oil is a naturally occurring insecticide and fungicide found in neem tree seeds. According to the National Pesticide Information Center, neem oil and its components “are used in over 100 pesticide products.”

Neem oil works by preventing fungal spores from penetrating plant tissue. While the oil won’t cure already infected grass, it does help contain the spread of disease.

Baking Soda Solution

You can apply a baking soda solution to your turf to treat small areas of lawn fungus. To use this treatment effectively, you’ll need to mix sodium bicarbonate with water.

Your goal is to create a solution strong enough to kill fungi but too weak to disrupt your soil’s pH balance.

How to Prevent Lawn Disease

Dethatching

Dethatching is the process of removing dead plant matter from your lawn. Thatch builds up between the base of grass blades and soil, creating an optimal environment for fungus to thrive. 

Most lawn care companies provide dethatching services, but you can also dethatch your lawn with a manual thatch rake, power rake, or vertical mower.

Core Aeration

Core aeration involves using a machine to pull cylindrical plugs out of the soil, adding natural fertilization and circulation to the turf. Core aeration helps prevent lawn disease by loosening compacted soil and stimulating grass growth. 

You should typically aerate your lawn about once a year, but you can increase the frequency if your yard gets heavy foot traffic or shows signs of standing water.

You can hire a landscaping company to aerate your lawn or do it yourself by renting an aerator from your local home improvement store. 

Watering

Set your sprinklers to water your lawn early in the day. Your grass needs about one inch of water per week to help it grow, but watering late in the day gives it less time to dry properly. Water early to help prevent your grass from staying wet and developing fungus.

Mowing

Ensuring proper lawn mowing techniques is another way to prevent fungus outbreaks in your lawn. 

Before the mowing season begins, sharpen your mower’s blades to avoid a ragged turf. Poorly cut grass is more vulnerable to fungal infection, so a clean mowing job is a must.

You also need to maintain a certain grass height depending on the type of grass in your yard. Common grasses like tall fescue should be cut at two to three inches. Warm-season grasses like Bermuda grass and Zoysia grass thrive at a one-inch cutting height.  

Lastly, clean up grass clippings after mowing. Infected clippings can spread fungus to other areas of your lawn or build up as thatch, preventing nutrients from reaching healthy growths.

Final Thoughts

We hope this article helps you understand how to treat fungal disease on your lawn. Homeowners have access to many treatment options, from DIY care to home remedies.

Remember that regular lawn maintenance is the best way to prevent fungal outbreaks in your turfgrass. The healthier your lawn is, the better equipped it will be to ward off pests and germs.

If you’re eager to dive deeper into top-notch turf maintenance, you can read our lawn resource guides for more information on fertilizing, seeding, year-round care, and more.

Other Lawn Resources