By Glenda Taylor | Published May 18, 2022 1:16 PM

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Even the best-tended lawn can develop a fungal problem, which can show up as visible brown patches, rusty-looking or yellow spots, rings of dead grass, and slimy areas. Fungi and their spores occur naturally outdoors and are found virtually everywhere, but they rarely wreak havoc with lawns unless they start reproducing rapidly. Certain situations, such as living in a humid region or experiencing a rainy season, can increase the risk of a fungal infestation in a lawn. Other potential causes include overfertilizing, overwatering, growing turfgrass that’s poorly suited to the area, or mowing the grass too short.

Today’s best lawn fungicide options are made with biocidal chemical compounds or biological organisms that kill parasitic fungi and/or their spores; for the most part, they will not affect weeds or desirable plants (though there are exceptions). Some products are formulated to stop an active fungal infestation, while others may be preventive to keep a healthy lawn looking great. Many fungicides also work to eradicate fungus on trees, shrubs, and ornamental plants, although, depending on the formulation, some may injure specific types of plants or trees. Ahead, learn about the different types of fungicides and find out why the following products are among the best antifungal options for keeping grass healthy and free from imperfections.

With more than 2 million different species of fungi, including all types of mildew, mold, yeast, mushrooms, and smuts, it’s not always possible to pinpoint the exact fungi species causing problems in the lawn. However, almost all grass-related diseases are caused by pathogenic fungi, meaning fungus that can cause an infestation. Hence, the first course of action with any visible lawn problem—including rings of dead grass; slick spots; or unsightly yellow, brown, or rusty patches—is to treat it with a fungicide.

While fungicides are loosely grouped into two categories—preventive and curative—all are preventative, but not all are curative. Choosing one will depend on whether there’s an active fungal infestation or whether you want to reduce the risk of one occurring. These products can contain either chemical or natural ingredients. In the long run, it’s better to prevent a fungal infection rather than wait until one occurs and treat it. While a curative will kill an existing fungus, it won’t repair the damaged lawn. The homeowner will have to replant grass in the dead areas.

All lawn fungicides will either kill fungi or prevent it from getting a foothold, but they do so differently, depending on the product.

With so many types of fungi that can infest turf grass, many fungicide products are broad-spectrum, meaning they work to kill or prevent infestation from a wide variety of fungal species. While there are exceptions, many systemic fungicides are broad-spectrum because the ability of the grass to absorb the product makes it more effective against a range of fungi. These products often bear the wording “broad-spectrum” on their labels. With a broad-spectrum product, the best fungicide for dollar spot is also likely to be the best fungicide for lawn rust.

On the other hand, narrow-spectrum fungicides are often contact fungicides that are designed to treat and prevent specific types of fungus species from reproducing. These products aren’t labeled as being narrow-spectrum. Instead, they will often list the type(s) of fungus symptoms they’re designed to treat, such as “brown patch” or “dollar spot.” Narrow-spectrum fungicides typically only treat one or two fungal diseases, so users should know exactly what type of fungal infestation is on their lawn before using a narrow-spectrum product.

Narrow-spectrum fungicides are highly effective against specific fungi species, and they are less likely to kill beneficial organisms such as arbuscular mycorrhizal, a fungi that helps increase nutrient uptake in plants. Unfortunately, if the type of fungus causing damage in the lawn is not known—which is often the case—applying a narrow-spectrum product may not get the job done.

While narrow-spectrum fungicides have their place, all the products in our lineup are broad-spectrum because they offer the widest range of fungal protection.

Fungicides come in various application types—some require mixing, while others come premixed and ready to apply.

Always read and follow the manufacturer’s application instructions carefully. Most fungicide products are safe when used as directed, but some may cause irritation if they directly contact skin or eyes or if they’re inhaled. To be on the safe side, wear gloves, long sleeves, and long pants when applying fungicide, and consider wearing a respiratory mask and protective eyewear if you’ll be using a product with a pump-type sprayer.

Antifungal products for use on lawns are typically safe for all types of grass. For the best result, wait 2 weeks after using a lawn fungicide before overseeding with new grass seeds to give the new seeds the best protection possible from fungal disease.

In our quest to find the best fungicide, we extensively researched dozens of products that claim to treat and prevent fungal infestations in lawns. To qualify for a spot on this lineup, the fungicide had to indicate whether it was a broad-spectrum product or designed to treat only one or two types of fungal infestations. Mixing instructions (if applicable) had to be simple to understand and follow, and the product had to come with positive reviews from users who applied it to their lawns.

Designed to kill and prevent brown patch, summer patch, red thread, and other fungi-related lawn diseases, BioAdvanced Fungus Control for Lawns is simple to apply and effective. It comes as a concentrated liquid in a hose-end dispenser that attaches to a standard garden hose for easy spray application.

One 32-ounce container will treat up to 5,000 square feet of lawn. This is a systemic fungicide absorbed by the grass blades to kill existing fungal infestations, and it remains active within the grass to protect the lawn for up to 30 days against reinfestation. Once it dries on the grass, the product is rainproof and won’t wash away. A broad-spectrum fungicide, BioAdvanced targets many of the most common types of fungal infestations, so it’s highly effective for controlling most lawn diseases.

Get BioAdvanced lawn fungicide at Amazon, Ace Hardware, The Home Depot, or Lowe’s. 

Keeping the lawn fungus-free needn’t cost a bundle. Spectracide Immunox Multi-Purpose Fungicide is made to kill a wide variety of fungi that can cause brown patch, black spot, powdery mildew, and more. It’s suitable for lawns, trees, shrubs, and ornamentals, including roses, and it’s a budget-friendly pick.

Immunox is available as a concentrated liquid that must be diluted with water before use. It can be used in a trigger-type hand sprayer to treat small areas or applied with a pump-type garden sprayer where broader coverage is desired. One 16-ounce bottle will cover up to 4,000 square feet of lawn. Coverage on trees and shrubs will vary depending on the size of the specimens.

Get Spectracide Immunox lawn fungicide at Amazon, Ace Hardware, or Lowe’s. 

There’s no mixing, no mess, and no need to worry about overspray when applying Scotts DiseaseEx Lawn Fungicide. This systemic fungicide prevents mold, mildew, and other fungi from destroying turfgrass. Scotts, a recognized leader in lawn seed, fertilizer, and treatment products, developed DiseaseEx to target 26 common fungal diseases, including brown patch, pink snow mold, and fairy ring, making it a broad-spectrum fungicide.

The product comes in granular form and should be applied with a broadcast spreader or a drop spreader. One 10-pound bag of DiseaseEx treats up to 5,000 square feet of lawn. The granules dissolve quickly and are absorbed by grass blades to kill existing fungi and protect the lawn for up to 4 weeks. In addition, users can apply fertilizer simultaneously to the lawn and then water to disperse both products at once.

Get Scotts DiseaseEx lawn fungicide at Amazon, Ace Hardware, The Home Depot, or Walmart. 

Heritage G Fungicide treats and prevents more than 20 different fungal diseases, including common ones such as brown patch as well as less common varieties like necrotic ring spot. The granules in Heritage G Fungicide dissolve quickly with light watering, rain, or even heavy morning dew, which reduces the risk of the product washing away or being picked up and bagged by a mower. The active ingredients are absorbed by grass blades, where they destroy existing fungal infestations and prevent reinfestation for up to 28 days.

One 30-pound bag treats up to 7,500 square feet of lawn. A potential downside to Heritage G is that it can harm apple trees and should not be used where dissolved granules could be absorbed by apple tree roots. Folks with apple trees on their property may wish to opt for a different fungicide to be safe.

Get Syngenta Heritage G lawn fungicide at Amazon or Kmart.

The Andersons Prophesy Spectrum Fungicide controls and prevents common fungal diseases, including brown spot, dollar spot, and pink patch. It comes in quick-dissolving granular form and can be reapplied every 2 weeks as necessary to keep the grass free of fungus.

One 25-pound bag of The Andersons Prophesy Spectrum fungicide treats up to 10,000 square feet of lawn, and users should apply the product with either a drop spreader or a broadcast spreader (not included). This fungicide is especially well suited as part of a preventive disease control program. It is both broad-spectrum and systemic and can keep fungus-related diseases away with regular use.

Get The Andersons Prophesy lawn fungicide at Amazon, Walmart, or Seed World.

While any lawn fungicides in this lineup will treat and protect turfgrass from various fungal diseases, our best overall pick, BioAdvanced lawn fungicide, ticks all the boxes. It treats the most common fungal infestations in lawns and comes in a handy hose-end dispenser. It also protects grass for up to 30 days. Our budget pick, Spectracide Immunox Multi-Purpose fungicide, is an affordable option for treating lawns, and it can also be used on shrubs, trees, and other plants.

Before narrowing down our list to the lawn fungicide products in this lineup, we extensively researched dozens of brands and types of fungicides. While we considered brand reputation (such as Scotts, a well-known name in lawn products), we didn’t automatically eliminate smaller manufacturers if the fungicides rated highly with users and effectively treated fungal diseases.

To an extent, we considered cost, but we placed greater emphasis on effectiveness and ease of use. We also tried to avoid fungicides that were highly toxic to humans and pets.

If you’ve noticed unsightly brown or yellow patches in the lawn, or that grass is dying in spots or looks slimy, there’s a good chance fungus is the culprit. Fortunately, most lawn diseases can be treated and controlled by fungicides. If you still have some questions about the best fungicide for lawns, read on for answers to some of the most common questions.

Any of the products in this lineup would be good choices for treating lawn diseases, but our top pick is BioAdvanced lawn fungicide for its ability to treat and prevent a wide range of fungal diseases.

The short answer is as soon as you notice a problem. Prompt treatment will keep the fungal disease from spreading and protect the rest of the yard.

The general rule is to apply a fungicide for lawn treatment in spring when low nighttime temperatures are around 60 degrees Fahrenheit. Then apply additional treatments as recommended on the package.

It depends on the product. Some fungicides can be reapplied every 2 weeks while others last up to 4 weeks, so follow the manufacturer’s recommended instructions.

If you’re applying a granular fungicide that needs to be watered to dissolve, you can usually apply a fertilizer simultaneously.

When applied as directed, it shouldn’t. However, keep in mind that the fungi that were affecting the lawn may have already damaged some of the grass, which could still die after you’ve applied a fungicide.

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