8 Best Fungicide for St Augustine Grass Reviews in 2023

Combat fungus problems in your St. Augustine grass lawn when you apply the best fungicide. We reviewed eight highly recommended fungicides to help you make the right choice.

Sean Stratton | Updated April 23, 2023

If your St Augustine Grass lawn was thriving a few weeks ago and suddenly you see some brown rings on it, this is a sign of a fungus problem. You need to act fast before things get worse. But how do you treat fungal diseases?

To help your lawn fight fungal diseases and thrive again, we put together this list of the best fungicide for St Augustine grass.

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8 Best Fungicide for St Augustine Grass Reviews

Finding the best fungicide to treat the fungus on St Augustine grass can be time-consuming. We did the legwork and compiled the following list of the best products to eliminate fungus on your lawn.

1. Select Source Propiconazole 14.3 Pint Select Fungicide

Propiconazole is a systemic triazole fungicide that is highly effective against a wide range of fungal diseases in St. Augustine grass.

Select Source Propiconazole Fungicide stops the fungus’s cellular growth and minimizes the disease’s impact on your lawn.

It works as a preventative and curative measure. And it controls lawn diseases like leaf spots, powdery mildew, brown patch, spring dead spot, and summer patch. It comes with many benefits, including low odor and better residual control. Its tank mixing compatibility is high, and the use rate is low.

You can also use it for ornamental applications. The Propiconazole fungicide is ideal for commercial lawns, golf courses, landscape ornamentals, and more.


  • Suitable for both ornamental and turf species.
  • Contains low odor; a better working experience.
  • Its tank mixing compatibility is high.


  • It’s not an ideal option for a brown patch.

2. Bioadvanced Fungus Control for Lawns

This fungicide comes in a ready-to-spray applicator that works through the grass’s stems and leaves, making it easier for your St. Augustine grass to absorb.

A single bottle of Bioadvanced Fungus Control for Lawns can treat up to a 5,000 sq ft area of grass, and regular watering or rainfall will not impact its effectiveness.


  • Rainproof: the fungicide will not get washed off.
  • Treats large area: covers up to 5,000 square feet area.
  • Easy to use, thanks to the hose applicator.


  • It doesn’t work on mealybugs.

Next Read: Top Fertilizers for St. Augustine Grass

3. Dow AgroSciences 173917 Eagle 20EW Fungicide

Fungi can turn your thriving St. Augustine lawn into a disaster. That’s why you must choose a fungicide that works inside out to save your beautiful lawn from frequent Fungi attacks. Dow AgroSciences came up with the Eagle 20EW Fungicide to help prevent and control typical lawn diseases.

Dow AgroSciences says their Fungicide can prevent and control more than 15 fungal diseases, including brown patches, dollar spots, necrotic ring spots, powdery mildew, leaf spot, and more. For best results, you need to apply the fungicide with an application schedule of 7-10 days.

You can also use this fungicide on vines, fruit trees such as apples, and ornamentals such as poinsettias, daylilies, chrysanthemums, and so on.


  • Capable of preventing and controlling 15+ fungal diseases.
  • Suitable for both ornamental and turf species.
  • It is easy to use; less hassle to apply.


  • You’ll need to wait to see the best result.

4. Scotts DiseaseEx Lawn Fungicide – Fungus Control, Fast Acting

Scotts DiseaseEx Lawn Fungicide works on 26 typical lawn diseases like red threads, brown patches, and powdery mildew. According to Scotts, this fungicide works just 24 hours after application.

The fungicide works in a preventative way if you use it on your St Augustine lawn to control brown spots before they appear. And in a curative way, apply it on your St Augustine lawn to treat signs of disease.

Start applying it before you see the symptoms as a preventative measure for best results. Another great thing about this fungicide is that it covers a large area. A 10-lb. bag is enough to treat up to 5,000 square feet.


  • Stops and prevents more than 25 lawn diseases.
  • Large area coverage; a 10 lb is enough for up to 5,000 sq. ft.
  • Works both in preventative and curative ways.


  • It doesn’t work well on grubs or mushrooms.

5. Spectracide Immunox Fungus Plus Insect Control For Lawns

Spectracide Immunox Fungus Plus Insect Control Fungicide fights typical lawn diseases and kills lawn pests on contact.

It prevents brown patches, powdery mildew, scabs, black spots, rust, and more. Plus, it controls harmful pests like sod webworms, brown dog ticks, and ants. For best results, apply this fungicide every 2 weeks as a preventative measure or as soon as you notice signs of disease.

Spectracide says that this fungicide becomes rainproof just a few hours after application, so you don’t need to worry about it getting washed away.


  • Able to kill harmful bugs on contact.
  • Treats large area; covers up to 2,500 square feet area.
  • Rainproof; the fungicide will not get washed off.


  • You may need to apply it multiple times for better results.

6. Grower’s Ally Fungicide | 32 fl. oz. Concentrate

This easy-to-use Grower’s Ally Fungicide is here to help if your lawn is affected by plant pathogens. It prevents harmful plant pathogens and encourages the healthier growth of your St. Augustine grass. If your only concern is bacteria, this fungicide acts like a natural disinfectant and effectively reduces bacteria’s growth.

OMRI lists it, so you get an idea about the overall safety of using this fungicide on your lawn. It doesn’t contain heavy metals or synthetic pesticides and has zero pollutants. The 32oz concentrate treats 8,000 sq. ft.

The use of this fungicide is not only limited to your St. Augustine grass lawn or outdoors. You can even use it in greenhouses, indoors, and in hydroponics.


  • Treatment control for powdery mildew
  • OMRI lists it as safe to use.
  • Contains food-grade citric acid, which reduces the growth of bacteria.
  • Treats an area of 8000 sq. ft.


  • Multiple applications needed

7. Bonide (BND60514) – Infuse Systemic Disease Control, Granular Fungicide

Bonide Infuse Granular Fungicide prevents and stops regular lawn diseases like brown patches, rust, dollar spot, leaf spot, and so on. This granular is also an excellent choice for shrubs, trees, flowers, etc. So, you get total support for your lawn from a single fungicide.

This granular fungicide on your lawn can be easily spread by hand. Works on Zoysia, St. Augustine, Ryegrass, Bluegrass, Bermuda grass, Bent grass, and more.

For effective results, use it when you notice the signs of any disease for the first time. It has an area coverage of 5,000 square feet.


  • Can be used on both warm and cold season grass.
  • Treats large area; covers up to 5,000 square feet area.
  • Besides lawns, it can be used on flowers, roses, shrubs, trees, etc.


  • It’s not practical for gray leaf spots.

8. Heritage G Fungicide 30 lb Bag

This granular fungicide controls diseases like red threads, brown patches, anthracnose, snow mold, etc. It is easy to apply.

A great feature of this fungicide is the DG-Lite carrier which helps it to get distributed to the target location with a bit of water only.

You can apply it to landscape areas, athletic fields, golf courses, etc.


  • Comes in granular form; easy to apply.
  • Comes with a carrier DG-Lite feature; minimal water is needed to disperse.
  • Can also be applied to landscape areas, athletic fields, and golf courses.


  • More expensive than similar options.

Things to Consider when Buying the Best Fungicide for St. Augustine Grass

1. Does this Fungicide Treat the Problem?

Many common lawn diseases can turn your beautiful lawn into a living nightmare. Among them are brown patches, red threads, powdery mildew, rust, snow mold, etc. But all diseases don’t affect your lawn the same way.

For example, brown patches are more likely to affect some Augustine grasses like Zoysia and Bermuda grass. The occurring rate of brown patches in these two types of grass is more compared to other fungal diseases. In most cases, a good-quality fungicide will help your lawn fight brown patches. However, checking before buying is always recommended and an intelligent thing to do.

Key Takeaway: before buying any fungicide, you should diagnose your lawn and find out what is causing the thriving lawn to turn into a disaster. After finding out the reason behind it, it’s time to check the fungicide label to make sure it can treat your lawn problem.

2. Is It Made for St. Augustine Grass Only?

It can be difficult to find a fungicide dedicated to only treating St. Augustine grass, but you can usually find it listed under general grasses.

3. What Ingredients Does It Contain?

You can’t just apply any fungicide that you find close at hand. You need to apply a fungicide that is safe for the grass, you, and the environment.

So, first, take a look at the ingredients. Make sure the fungicide contains non-toxic materials and sulfur. For better results on your St. Augustine grass lawn, look for fungicides that come with rosemary oil, neem oil, and jojoba oil.

4. Is It Granular or Liquid?

This depends on your preferences. There are plenty of fungicides from both sides, granular and liquid. The working principle will be different for both types.

If you are comfortable with granular fertilization, you can skip the liquid ones. But if you want something that can be done with less hassle, you can choose liquid fungicide.

5. How Much Area Can It Cover?

Generally speaking, fungicides can be expensive. That’s why you should be concerned about how much area can be covered with a single package of fungicide.

First, measure the area you want to treat so you can be sure that you have enough fungicides for your needs.

Also Read: How to Plant St Augustine Grass Plugs

Signs of Fungus on St. Augustine Grass

There can be different signs of fungus on your St. Augustine grass. And depending on the fungus type, the signs will vary. But here are some common signs that indicate that your lawn is affected by fungi.

  • Leaf rot: Rotting leaves signify that your St. Augustine grass lawn is affected by brown patch disease.
  • Fairy rings: If you see mushrooms appearing in your lawn, especially in a circular shape, consider your lawn is affected by fungus.
  • Small circular patches: If you see these 2-3″ patches on the grass, consider you are having dollar spot disease on your lawn.
  • Pythium root rot: Sometimes, you will not notice any signs of disease by looking at the physical appearance of the grass. You may notice the lawn is just getting thinner. But if you carefully examine the grass’s root, you will notice the main root has become thin.

How to Treat St. Augustine Grass Fungus

Step 1: Apply fungicide

After identifying the disease, immediately apply the fungicide that works best for that disease. You may need to apply the fungicide more than once, depending on the lawn’s condition.

Step 2: Sod replacement

Spot the disease-affected areas on your lawn and replace those sods with new healthy sods. This is an intelligent way to deal with fairy rings.

Step 3: Making acidic soil

To prevent diseases like take-all root, make the soil pH slightly lower so it can turn into slightly acidic soil.

Step 4: Proper watering and better drainage

Fungi love wet soil so avoid overwatering your lawn. Your St. Augustine grass only needs about 1 inch of water a week. Also, make sure that your lawn has a sound drainage system.

Frequently Asked Questions

Fungi can have a significant impact on your St. Augustine grass. Fungal diseases make the root system weak and even kill it in extreme cases. Other diseases like leaf spots or large brown patches cause dead patches on St. Augustine grass.

Look for the following signs of fungus in your St. Augustine grass:

  • Brown patches
  • A circular or ring structure of dead grass on the lawn
  • The growth will look rusty
  • A powdery coating or spots on the grass blades
  • Slimy areas

Final Thoughts

Fungal diseases can damage your thriving St Augustine Grass lawn. If you don’t treat the problem, it may cause permanent damage to your lawn.

In this article, we compiled a list of fungicides that we consider the best for your fungus-affected St. Augustine Grass lawn. Give them a try and take control of the fungus population on your lawn.

Written by Sean Stratton

Sean Stratton

Hi, I'm Sean, the senior editor here at Fertilizer Pick. I grew up on a farm in North Carolina and have grown fruits, vegetables, and trees since childhood. While I no longer live on a farm today, I still enjoy spending time on my garden and sharing my knowledge with friends and fellow garden enthusiasts.