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Fungal Diseases in your Lawn

Maintaining a healthy, vigorously growing lawn is the best way to prevent a severe disease outbreak in turfgrass. Each square foot of turf contains about 500 to 1,000 individual plants, each requiring optimum amounts of water and fertilizer, the right mowing regime, and an aerated, well-drained soil. If any of these factors are missing or in excess, the grass may become stressed and more susceptible to disease.

Selecting a turfgrass species that is adapted to the South Florida climate and intended use, then following through with cultural practices that favor the grass rather than the pathogen, are important steps a home gardener can take to avoid severe lawn diseases.

Many common diseases are active only under specific environmental conditions and will affect the lawn only for a short time. When the weather becomes more favorable to growth of the turfgrass, the lawn will often recover on its own if proper cultural practices are followed. However, if conditions and practices that favor disease are allowed to continue, the result can be long-term damage to the lawn that is difficult to recover from. Although we can’t control the weather, selecting the right grass and good cultural practices are keys to reducing disease. Fungicides are usually not needed for lawns when the right grass is planted and maintained correctly.


Identifying the Problem

The cause of lawn damage is often difficult to identify, and diseases aren’t always the primary cause. It’s a good idea to inspect your lawn once a week to immediately identify problems and act quickly to determine the cause before it’s too late. Diseases tend to start off as small patches or spots of dying grasses that spread over time. If the damage is sudden, widespread, and severe, other pests or problems such as insects, pathogens, weeds, or environmental stress may be contributing to the observed symptoms. Damage that resembles disease symptoms may also result from incorrect watering, fertilizing, or mowing practices.

Irrigation problems are the most common cause of discolored lawns. Fixing broken sprinklers and conducting tests to ensure even water coverage might be all that is necessary to improve the health and appearance of a lawn. No amount of fungicide will control a problem that results from poor watering practices.

Almost all lawn diseases are the result of pathogenic fungi that infect the blades, stems, or roots of turfgrass plants. Such diseases often are diagnosed by identifying symptoms of the disease and signs of the causal agent. Typical signs and symptoms include leaf spots; white, powdery growth; thin, open grass; and small to large areas of discolored or dying lawn.


Lawn fungal diseases take on a variety of forms – from dead-looking brown patches to highly visible spots, threads, rings, or slimes. And once they strike your yard, grass fungal diseases can be difficult to treat. Fortunately, the right lawn care practices can go a long way toward prevention and treatment; and in severe cases, a fungicide can help eradicate the spores to keep it from spreading. Here are some tips for preventing and treating fungal diseases in your lawn.

Causes of Lawn Fungal Disease

Your lawn is naturally full of fungi and spores, some harmless and some problematic, but the right (or wrong) conditions can cause grass fungus to erupt into a harmful disease. The most common causes of a lawn fungal disease are:


  • Drought

  • Improper mowing (especially mowing too low)

  • Compacted soil

  • Overwatering

  • Too much fertilizer (or using the wrong kind)

  • Wrong grass type for your yard

  • Weather conditions (particularly temperature and humidity)


Common Lawn Fungal Diseases

There are quite a few fungal diseases that can impact lawns, but they’re usually pretty specialized, targeting specific lawn types, at certain times of year, under certain conditions. For example:


  • Brown patch strikes during hot, humid weather.

  • Fusarium blight prefers hot, drought conditions.

  • Dollar spot tends to spring up when nights are cool and dew is heavy.


Before treating your lawn, it’s important to identify not only whether your lawn indeed has a fungal disease, but to identify the fungus itself. All fungicides aren’t the same, and some diseases can be easily treated by making changes in your lawn care.

Knowing your grass type and recent weather conditions can make it easier to narrow down, but you may need help in figuring out exactly what’s going on. Your certified technician is your best resource for determining which diseases are most common in your area, or you can bring a small baggie of the infected grass to Hugh Turner Pest Control for proper identification.

Prevent and Treat Lawn Fungal Diseases

A simple change in your lawn care practices may be enough to prevent or eradicate lawn fungal disease. At other times nature may deliver a soggy spring or summer heat wave that just can’t be helped. Stressed or unhealthy lawns are much more likely to develop disease; so the better you care for your lawn, the better the grass will be able to handle the natural conditions in your area.

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