Turf Wars: How to Treat Lawn Fungus

You’ve worked hard to establish that lush golf course lawn and it’s rightly become a source of pride. But while taking every chance to enjoy the fruits of your labor, it’s important to stay alert for the many pests and diseases that are just as attracted to that awesome lawn as you. 

Fungal spores can remain dormant in topsoil; others can literally blow in on the breeze. In either case, given the right (or more correctly wrong) conditions, fungal diseases present one of the most frequent threats to turf grasses and can prove every bit as hazardous to your lawn’s health and appearance as insect infestations or common critters. 

Most fungal lawn diseases attack the grass plant’s root structure, with symptoms displaying in the leaf and stem, but it’s important to remember that these diseases are most often caused by an imbalance in the fungus and mycelium found naturally in all healthy turf, and are essential for breaking down and converting dead organic matter. 

As with all battles, knowing your enemy is the key. So, before deciding how to treat lawn fungus, the first step is always identifying which of the many possible varieties is afflicting your lawn.

Spore-lore: Identifying Fungal Outbreaks

To this end, we’ve compiled a list of our top six “least wanted” but most common varieties of fungal disease afflicting turf grasses.

Brown Patch

Brown patch is by far the most prevalent of all fungal turf diseases. Present all over the world, it can attack all turf grass varieties. Caused by the Rhizoctonia solani fungus, the symptoms are self-explanatory, as the blight creates dead brown patches in lawns. These roughly circular areas can range in size from a few inches to a few feet. 

To support a correct diagnosis of brown patch, check for pale, cobweb-like strands of the fungal mycelium around the outer perimeter of the affected area. You’ll need to do this in the early morning (before the temperature rises above the dew point).

Dollar Spot

Dollar spot is another common fungal disease that can be hard to differentiate from brown patch, as both create areas of brown blight within turf. However, as the name suggests, dollar spot, caused by the fungus Clarireedia jacksonii, initially appears as small, straw-colored spots that often leave a slight depression in the grass. 

Dollar spot affects all lawn turf, but shorter-mowed grass with nitrogen deficiency is particularly susceptible. If you don’t treat it, the spots will merge to form larger areas, but identifying light tan lesions on leaves bordered by a cinnamon-colored band will let you know this is dollar spot rather than brown patch.

Powdery Mildew

Powdery mildew is another common lawn disease, this one caused by the fungus Erysiphe graminis. The spores produced by this fungus adhere to the stems and blades of grass, making infected areas relatively easy to identify, as they look as if icing sugar has been sprinkled over them. Left untreated, these areas will begin to yellow over time. 

Instances of powdery mildew have much to do with external circumstances and are more likely to develop in conditions of high temperature and humidity, stagnant air circulation, and dense shade. Aside from looking unsightly, powdery mildew does little immediate harm to grass, but it will eventually begin to stress and thin out the lawn.

Red Thread

Red thread is caused by the fungus Laetisaria fuciformis and presents as small gelatinous, pinkish-red strands (called stroma) less than a quarter inch long, which can be found among the pale, dead grass it has infected. It casts affected areas with an overall pinkish hue. 

Red thread usually occurs between spring and late summer, especially when those periods have been particularly wet. Aside from overly humid and damp weather, red thread can also indicate that your soil doesn’t contain sufficient nitrogen. Fortunately, red thread doesn’t affect your grass root systems and is relatively easy to control.

Snow Mold

Snow mold, caused by the fungus Microdochium nivale, is one of the most damaging fungal diseases affecting turf grasses and can be challenging to control. Although it can happen at any time of year, as the name suggests, snow mold most often occurs during the colder months of fall and winter. Its effects can be exacerbated by snow melt in early spring, which leaves thawing ground saturated.

Snow mold patches, which can reach over 12 inches in diameter, are pale, often grayish, circular areas of dead grass, sometimes containing patches of black mold (called sclerotia) or sometimes in wet conditions, a pale pink or white cotton-like fungal growth.

Necrotic Ring Spot

This sinister-sounding disease is caused by the fungus Ophiosphaerella korrae. This soil-borne fungus attacks grass roots, creating dead yellow areas in lawn turf that manifest as roughly circular rings rather than patches, often leaving a depression in the affected turf. 

This fungus typically infects grass during cool, wet weather, especially fine fescues and bent grasses. However, drought and high soil compaction can also stress turf grass, leaving it susceptible to necrotic ring spot.

Related reading: Your Ultimate Winter Lawn-Care Guide

Preventing Fungal Outbreaks in Your Lawn 

When it comes to how to treat lawn fungus, we firmly believe that prevention is better than cure. For some types of fungal diseases that can affect turfgrasses, there simply is no ‘one-time’ method of eradication. It takes long-term dedication to create and maintain a robust, well-nourished, and well-drained lawn. This is one of the best ways to improve your lawn’s resilience to fungal disease. 

These basics of good lawn care go a long way to mitigating the risks and effects of fungal diseases, as well as reducing susceptibility. Throughout the growing season, we suggest you allocate time to: 

• Dethatch: This simple process of removing the dead organic debris, from tree leaves to grass clippings, that can quickly build up over the surface of your lawn. Dethatching removes a fungus habitat while radically improving the quality of your soil.  Removing the barrier layer of thatch (preferably with a thatching rake or scarifier) allows the right amounts of water and oxygen to reach grass roots to keep them strong and healthy.

• Water: Ideally, your grass needs around an inch of water every week to promote growth. We recommend watering early in the morning between 4-6 AM. This allows adequate time for the water to penetrate the soil, helping you get the most out of your spend on water. Evening watering can leave grass too wet and promotes conditions that aid fungus growth. 

• Mow: During mowing season ensure your blades are always sharp to prevent ragged turf. Dull mower blades tear the grass, leaving it far more susceptible to lawn diseases. It’s also important to always cut your grass at the right height according to the variety. Generally speaking, Tall Fescue, Fine Fescue, Kentucky Bluegrass, and Perennial Ryegrass do well at mowing heights of three to four inches, while Bermuda Grass, Centipede Grass, and Zoysia Grass thrive at lower mowing heights below 1.5 inches. Cutting grass shorter than it naturally prefers puts it at greater risk of fungal infection.

• Core Aerate: This involves using a lawn aerator to remove 2-4 inch plugs of soil roughly a half inch in diameter from your lawn at regular intervals. This reduces compaction while allowing water, air, and nutrients to properly percolate into the soil. Ideally, core aeration should be done at least once a year. 

 Related reading: The Most Effective Fungicides to Use on Your Lawn

Controlling Fungal Diseases in Your Lawn

When it comes to repairing diseased lawns, fungicides are an excellent tool for speeding up the process. After application, patience is the word of the day. Depending on the extent of the damage, it can take 2 - 3 weeks before there’s a visual improvement in the lawn.  Supplementing the lawn care practices above, in the case of: 

Brown Patch: Avoid overfertilization. Excessive nitrogen in the soil creates conditions that make it easier for this disease to establish.  Apply a specially formulated lawn fungicide such as Pillar SC or Headway G. 

Dollar Spot: Remove dew and excess moisture, ensure good drainage, and ensure the lawn has adequate nitrogen. Apply specially formulated fungicide such as Pillar SC  or Headway G. 

Powdery Mildew: Fortunately, powdery mildew can be treated with several natural remedies, including the application of a milk spray comprised of 40% milk and 60% water or a highly effective baking soda spray, a solution made from a tablespoon of baking soda and a teaspoon of liquid soap mixed into a gallon of water. 

Red Thread: Drain, aerate, and scarify turf to promote increased airflow. Apply a nitrogen fertilizer as part of your normal nutrient program. 

Snow Mold: In the fall, prevent with an appropriate broad-spectrum fungicide, such as Pillar SC or Headway G. We recommend fungicide applications in October and November to help prevent snow mold. 

Necrotic Ring Spot: Apply an appropriate broad-spectrum fungicide, such as Pillar SC or Headway G, in early spring. Apply elemental sulfur amendments to inhibit NRS by raising soil acidity. Aerate the lawn to relieve compaction.

An important tip if you’re dealing with an active lawn disease outbreak is to mow the affected areas last. It’s also a good idea to wash your mower blades to avoid spreading the disease to other areas in the lawn. 

At the Golf Course Lawn Store, we understand that your first encounter with lawn diseases will likely be when you see its effects. 

That’s why we stock a range of carefully selected fungicides from industry leaders like BASF and Syngenta so that rather than worrying about how to treat lawn fungus when it occurs, you’ve got a range of effective solutions at your fingertips.

Recommended Products

1. Headway G Granular Fungicide

If you're contending with an active fungi outbreak, we recommend a subsequent application of Headway G fungicide after a 28-day interval. A single 30-pound bag of Headway G can cover an area ranging from 8,500 to 15,000 square feet, contingent on your chosen application rate. This combination fungicide is easy to apply using a broadcast spreader. If you prefer a liquid fungicide, you may want to explore our next recommended product, Pillar SC.

For the best results, apply Headway G in the spring (May or June) and again in the fall (October or November) to proactively control lawn diseases.

We highly recommend this product because its two ingredients combined help prevent and eliminate a wide spectrum of lawn fungi. This means you only have to buy one product, saving time and money. 

Common lawn fungi controlled by Headway G:

• Brown Patch
• Dollar Spot
• Fairy Ring
• Gray Leaf Spot
• Large Patch
• Necrotic Ring Spot
• Pythium Blight (preventative)
• Spring Dead Spot
• And many more (check the label for details).

2. Pillar SC Liquid Fungicide - Brown Patch and Dollar Spot Control

One of its standout features is its expansive coverage, capable of treating areas as extensive as 43,500 square feet, making it a cost-effective choice for larger lawns. Furthermore, its liquid formulation ensures quick disease knockdown, providing a rapid response to disease infestations.

Pillar SC is designed with user-friendliness in mind. It offers a straightforward, one-application-rate-fits-all approach, making it accessible and convenient to use. Combining the strength of two fungicides, Pillar SC delivers long-lasting and comprehensive protection against even the most resilient turf diseases, ensuring your lawn remains disease-free.

Beyond disease control, Pillar SC also contributes to enhancing plant health, fostering the growth of beautiful and robust grass, even in the face of various stressors. Importantly, it is safe for use on all grass types, offering versatility and peace of mind for lawn owners.

Related reading: Complete Guide to Identifying, Fighting and Preventing Lawn Diseases

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