Problems With St Augustine Grass: Uncover the Mistakes That Are Ruining Your Dream Lawn

Last Updated on April 12, 2023 by Mattias

Problems with st augustine grass can appear in the form of diseases, fungi, insects, and even weed infestation. There is no doubt that St augustine develops beautiful turf on your property, but even this easily maintainable grass isn’t immune to lawn problems. Certain things trigger problems in this grass variety, and if they are not resolved promptly, your entire lawn can get damaged.

If you wish to avoid the fatal consequences of neglected problems in your lawn, then you should be able to identify them in the first place. Keep reading this article to get a comprehensive overview of the problems with st augustine grass.

Problems With St Augustine Grass 

There are several potential problems with st augustine grass, but the most common ones are listed below. 

Brown patch disease

Brown patch, also known as the large patch, is a type of disease that originates from the fungus pathogen Rhizoctonia solani. Brown patch disease targets new leaf blades and damages your grass roots from within. The transfer of food and nutrients gets hindered because severed roots and grass blades turn dull. This causes unsightly brown spots to appear on your lawn, and even though they will be small and harmless in the start, they will grow rather quickly and cover the entire lawn in circular patches.

If you’re wondering when to look out for this disease then late spring and early fall should be your main targets. The brown patch can appear on your lawn when the night temperature drops below 70 degrees Fahrenheit, and the daytime temperature reaches 80 degrees. Almost all types of fungi thrive in these conditions and get an open window to attack healthy grass.

Wet weather is the primary attraction for this grass, which means it can also appear in humid conditions. As summer approaches, the temperature tends to get moist, and the grass begins to come out of dormancy.

One of the worst things about the brown patches is that this disease can attack and disguise as dormant grass. You’d assume that your grass is not returning to its original color because of dormancy, but a fungal disease would have affected its growth. You might not even notice until it’s too late.

Some main causes of brown patch disease are cooler temperatures, poor drainage, thatch build-up, moist soil, overwatering, and excess nitrogen fertilizer use.

Symptoms of brown patch disease 

  • White mycelium resembling spiderwebs will form on your leaf blades when the grass is wet
  • Circular brown patches that have diversified sizes
  • Patches of tan grass ranging all the way up to 3 feet  
  • Margins may turn smokey and grayish
  • Wilted and dying grass 
  • Yellow, brown, and orange colored patches
  • Unusual patterns on your turf
  • Grass plugs will not show resistance when pulled

Treatment options for brown patch disease 

If you have noticed the above-listed symptoms then your St augustine lawn is most certainly attacked by brown patch disease. Dormant grass may not be actively growing, but its roots are still strong, so the main indicator for the brown patch disease should be the fact that the grass plug is easily removable from the soil surface.

The best way to prevent this problem in your lawn is by taking necessary actions and fixing the thing that caused it in the first place. You should change your watering routine and never water at nighttime. A good drainage system should be ensured, and soil conditions should be checked regularly. Other precautions include soil aeration and dethatching. In simple words, if you make sure that your st augustine grass is getting proper lawn care, then fungal diseases such as this one won’t attack.

If the situation has gotten out of hand, then you can treat brown patch disease by applying suitable fungicides. Some of the best options are myclobutanil, thiophanate methyl, and azoxystrobin.

Nigrospora stolon rot

Nigrospora stolon rot is a fairly new disease that is most likely to affect the grass stem. Doing so makes sure that nutrient transfer is completely halted and stolons have started going under stress.

When this happens, the leaf blades also suffer from nutrient deficiency and show signs of drought stress. Simply put, this disease kills your grass by interrupting the transfer of nutrients and letting it starve to death. At first, the leaves will only thin out, but as time passes, they won’t be able to survive.

Nigrospora stolon rot is most likely to girdle the stolons during hot and dry temperatures hence you should be keeping an eye out during the summer season. 

Symptoms of Nigrospora stolon rot 

  • Dead grass will turn yellow
  • Leaves will appear to be wilted
  • Darkened roots
  • Thin grass
  • Dead stolons and leaves 

Treatment options for Nigrospora stolon rot 

Fungicide treatments can solve the Nigrospora disease problem. Since this is a new disease, there isn’t a range of cultural practices recommended just yet, but you can surely prevent it by avoiding its triggers.

Your lawn should be watered properly during the summer season, and unhygienic conditions such as thatch buildup should be avoided at all costs.

Gray leaf spot disease 

Gray leaf spot is a lawn disease that is most likely to occur in st augustine grass. It is caused by the fungus Pyricularia grisea and it thrives in hot humid temperatures. Since its ideal conditions are frequent rainfall, gray leaf spot is most likely to occur in areas such as Florida. It can also appear if your lawn has a high moisture level, improper watering schedule, or if it’s under shade for longer. This disease attacks in late spring and early summer, the peak growing seasons for warm-season grasses. 

Your st. augustine lawn is most vulnerable to this fungal disease in the first year of establishment. Afterward, the risk of diseases and your fully grown turf becomes less likely to get attacked. You should be extra cautious of this disease when temperatures are between 70 degrees Fahrenheit and 95 degrees. If your grass remains wet for a long period of time (approximately 14 hours) then small oval-shaped spots will appear on St. Augustine’s leaves, and that’ll be the start of this disease. 

It will slow down your turf’s growth, thin it, and kill it eventually.

Symptoms of gray leaf spot disease 

  • Signs of drought stress
  • Dot-like spots appear on the grass blade and eventually turn gray 
  • Oval-shaped and tan-colored leaf spots are the first to appear
  • Tan-colored spots will be marked with a dark brown border
  • Small patches join together and form large, irregularly shaped patterns
  • Leaf blades tend to appear greasy
  • Thin grass
  • Withered and dead grass will turn brown

Treatment options for gray leaf spot

Gray leaf spot is a threatening fungal disease, and the most effective way to get rid of it is by using fungicides. It can evolve to resist it over time, but the best options are azoxystrobin, pyraclostrobin, and fluoxastrobin. You can see the label directions for the best method.

If you want to prevent this disease from ever happening, maintain a healthy lawn. Much like other fungal diseases, gray leaf spot is also attracted to poor land conditions. You should mow frequently to get rid of dead leaf tissue and excess unhygienic material.

As we already mentioned, this disease starts infecting when your st. augustinegrass remains wet for a prolonged time. You should adopt a suitable watering routine and take preventative measures to ensure your lawn dries off quickly. A good drainage system should be installed, and overwatering should be avoided. 

Fairy ring disease

Fairy ring is one of the most common disease problems, and they can affect almost any type of turfgrass. It can originate from various species of fungi, but basidiomycetes are the primary ones. Fairy rings are most likely to occur in areas with decayed organic matter, such as tree branches, stumps, logs, or leaves buried beneath the ground.

The organic matter that remained there would be decomposed by fungus, forming rings in st augustine grass. The fungus starts decaying matter from the center, reaching outward, so if this problem is left unattended, rings can expand and take over large areas.

Fairy rings can occur any time of year except winter months, and they will be attracted if your lawn has sandy soil, less moisture, less nitrogen, or thatch buildup.

Symptoms of fairy ring disease 

The symptoms of this disease mainly depend on the type of fungi that attack your lawn, but here’s what you can expect.

  • Accelerated growth
  • mushrooms
  • Rings that may start from 1 foot in the beginning but reach up to 100 feet in diameter over time
  • Dark green rings with dead turf inside
  • Dark green rings with no dead grass
  • Trace of dead grass along the edges of the ring
  • Rings of dead grass 

Treatment Options for fairy ring disease 

Fairy ring disease is not as much of a dangerous problem, but that doesn’t mean that it shouldn’t be treated. If not controlled in time, these necrotic arcs can range all the way up to 100 feet in diameter.

You can solve this problem by simply removing the turf from affected areas and putting sod afterward. If your lawn only shows symptoms of mushrooms, they should be pulled out and disposed of as well.


Much like any other type of grass, St augustine is also vulnerable to insects. You may not know this, but lawn insects are much more dangerous than one expects, and they can greatly damage your lawn.

They attack your lawn due to certain climatic conditions, but the main attraction is poor lawn maintenance. Insects essentially thrive in ill-kept lawns, and they are extremely hard to get rid of when they find suitable conditions. Several species of insects can harm your St. augustine turf, but the most common ones are chinch bugs, white grubworms, and mole crickets.

Chinch bugs are small insects that can be rarely seen without a magnifying glass and are unlikely to be found alone. They travel in groups and live under the thatch layer on your lawn. One of the reasons why they are so common in Florida is that these bugs love high temperatures. They are threatening because not only do they suck the juice from leaf blades, but they kill the grass as well. Chinch bugs are fast spreading, and even after you get rid of them, they leave eggs in their wake.

Grub worms thrive in humid climates, which is common in Florida lawns as well. These insects live underground, which is why they are difficult to identify. They affect your grass roots from within and damage them so much that the transfer of nutrients is hindered. When the leaf blades do not get essential components, they turn brown and eventually die.

There are several species of mole crickets, but short-winged ones are particularly attracted to st augustine grass. These insects live near the soil surface and damage the root system. Mole crickets kill your grass by feeding on its roots, stems, and shoots. They also tunnel through the soil and loosen the grassroots. This disrupts the connection with the soil and makes it impossible to absorb nutrients. The grass eventually dries out and dies because of bulged-up ground.

Symptoms of Insects

  • Symptoms of insects resemble signs of drought stress
  • Irregular patterns on your lawn
  • Patches of yellow dead grass 
  • Grass will start thinning
  • White grubs can be found by digging the soil
  • Mole crickets cause the earth to bulge upward

Treatment options for Insects 

You can use chemical measures such as insect killers to treat this problem in your lawn, but if you don’t want to take risks, cultural practices will also show the best results.

As mentioned above, insects are more likely to attack when your lawn is in poor condition, so the most effective treatment is maintaining a healthy lawn. Insect killers and other products will certainly eliminate them, but there is no guarantee that their eggs will also be eliminated. If you want a permanent solution, then lawn care is your answer. 

Since most of the insects adopt thatch layer as their breeding ground, you should dethatch and aerate regularly. Overwatered lawns with high soil moisture are also an inviting condition for insects which means an adequate watering schedule will surely help you out.


St augustine grass holds its ground pretty well and is unlikely to be infested by weeds. However, if your lawn doesn’t have proper lawn care, weeds are a possibility.

Weeds are bad for your lawn because they compete with grass for primary nutrients and slow their growth. Some stubborn weeds, such as bermuda grass can even take over your entire lawn and remove any signs of st augustine grass.

The most common broadleaf weeds in st augustine grass include dollar weed, chickweed, henbit, and clover. Dandelions, bermudagrass, or crabgrass can attack too.

Symptoms of weed problems in st augustine grass

  • The best way to know whether weeds have infested your lawn is by evaluating it regularly. Broadleaf weeds are easily distinguishable thanks to their distinct appearance so you can notice them immediately. If you see an aggressively growing species in your lawn, then it’s time to head toward weed control.

Treatment options for st augustine

Several effective ways can help you get rid of weeds in your lawn. Firstly, make sure to remember that weeds have only infested because your st augustine grass wasn’t strong enough to fight them. You should take the necessary measures and fulfill your grass growth requirements.

Since St augustine is a low-maintenance grass, it only needs limited water, sunlight, and fertilizer to grow. If you encourage its growth, the grass will fight off weeds. 

Here are some other methods

  • Don’t mow for a while because tall grass will absorb nutrients much more competitively
  • Pull the weeds out by hand
  • Use pre-emergent herbicides and post-emergent herbicides
  • Use other weed control products such as selective herbicides.

Take-all root rot

Take-all root rot (TARR) is a dangerous fungal disease that mostly attacks st augustine grass and Bermuda grass. It originates from a Fungus called Gaeumannomyces graminis var and lives in the soil. One of the worst things about this specific problem is that it can attack a healthy lawn just as much as a poorly kept one.

You might not even notice when take-all root rot enters your lawn because this disease can stay hidden for a long time. This disease is most likely to activate during the summer months because St Augustine’s growing season is also thriving. 

Take-all root rot does precisely what its name suggests. It takes over your lawn and damages the roots until leaf blades can’t absorb the necessary nutrients from the soil. This disease can kill your entire lawn and affect large areas pretty quickly.

It is most likely to attack a lawn with sandy soil and thatch buildup, and experience high rainfall. 

Symptoms of take-all root rot

  • Brown and wilted grass
  • Irregular patches that may range from 1 inch to 20 feet in diameter 
  • Brown patches
  • Thin grass
  • Yellowed leaf blades that will turn brown over time 

Treatment options for take-all root rot 

The best way to treat this disease is to prevent it in the first place. Since it is one of the most dangerous and fast-spreading problems, you should always be cautious of it. 

Make sure to maintain a healthy lawn that is adequately watered. Overwatering is even more dangerous than underwatering, meaning you should water the grass deeply but infrequently. Apart from that, a healthy root system should be encouraged, and growth requirements should be fulfilled. 

Another recommendation is to conduct regular soil tests and evaluate soil samples to see whether the conditions are healthy and suitable for the grass.

Problems With St Augustine Grass Summary

St augustine is a warm-season grass that is popular because of its pleasant appearance and low maintenance characteristics. If you have an established St. augustine grass lawn or are thinking of starting one, you should be well aware of the problems.

When we choose grass for our properties, we only look for that grass’s characteristics, features, benefits, and drawbacks. A common mistake is that we never learn about the potential problems that can attack and damage your grass in the future. 

In this article, we discussed the most common st augustine problems i.e, brown patch disease, Nigrospora stolon rot, gray leaf spot disease, fairy ring disease, insects such as chinch bugs, weeds, and take-all rot. We also talked about their nature, symptoms, and possible treatment options.

Lawn health is a great sense of pride for lawn owners. We hope this article helps you reduce problems with st augustine grass and maintain a healthy lawn. 

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