What to Do About Lawn Fungus

February 15, 2024
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What is Lawn Fungus?

Lawn fungus is a common disease that can develop in any area. It affects many types of grasses, causing unsightly patches, discoloration, and even death of the grass.

Fungal diseases can develop due to a variety of factors, including environmental conditions, poor lawn care practices, and the presence of certain pathogens in the soil.

By understanding what causes lawn fungus and how to identify the specific type affecting your lawn, you can implement the appropriate treatment and prevention measures to restore your lawn’s health and appearance.

What Does Lawn Fungus Look Like?

Lawn fungus can present itself in several different ways, depending on the specific type of fungus and the grass species affected. Some common signs of fungal infections include:

  • Patches of discolored or dying grass, ranging in color from yellow to brown
  • Circular or irregularly-shaped spots on the lawn
  • Fuzzy, powdery, or slimy growth on grass blades
  • Rings or arcs of mushrooms or other fungal growths

Baking soda, also known as sodium bicarbonate, is a type of salt. And all salts are corrosive when too much is used.

Baking soda can kill lawn fungus but can easily damage grass or slow its growth if used incorrectly or excessively. Proceed with caution.

Here’s how to make a safe solution. You will need: 

  • 1 tablespoon of baking soda
  • 1 tablespoon of vegetable oil
  • 1 teaspoon of liquid soap that doesn’t have detergent
  • 1 gallon of water

Mix all of the ingredients together. The soap helps the solution spread out and stick to the grass blades or plant leaves. This helps the baking soda do its job.

As with any treatment, monitor its effects closely for results. Contact a lawn care pro for help if your lawn turns yellow or if you notice that stems aren’t developing. This is a byproduct of too much alkaline in your soil, most likely caused by the baking soda.

Vinegar is also a popular solution people use to get rid of lawn fungus. This is because the acetic acid in vinegar can kill the fungus spores and stop them from growing. But be careful when you use vinegar on your lawn. If you use too much, it can hurt your grass and other plants.

Here’s how to use it safely:

Mix white vinegar with water. Most people use half water and half vinegar. Put your vinegar solution in a spray bottle and spray it on the parts of your lawn where the fungus is. Keep a close eye on the areas you treated with vinegar. If the grass looks hurt, consider calling a professional. If the fungus keeps coming back, you might need a more robust and consistent treatment plan.

Here are five steps you can take to reduce the risk of lawn fungus. If you can handle these correctly and consistently, the risk of this lawn disease ruining your yard will go way down.

  1. Water your lawn properly.

Ensure that your lawn receives sufficient water, but avoid overwatering. Water deeply and infrequently, allowing the soil to dry out between waterings. And always add water in the morning. You don’t want your lawn to stay wet for prolonged periods because that is the primary factor in breeding lawn fungus.

  1. Mow at the correct height.

Mowing your grass too short can stress the turf and make it more susceptible to fungal diseases. Adjust your mower blade to the recommended height for your specific grass type.

  1. Aerate and dethatch. 

Regularly aerate and dethatch your lawn to improve soil drainage and reduce the buildup of organic matter that can harbor fungal spores.

  1. Fertilize appropriately.

Use a slow-release, balanced fertilizer to provide your lawn with the necessary nutrients for healthy growth. Avoid over-fertilizing, which can promote fungal growth.

  1. Maintain proper lawn hygiene. 

Remove fallen leaves, large rocks, tree limbs, and other debris to reduce the risk of fungal infections. Grass clippings from a routine mowing are good for your grass so there’s no need to remove them. Keep your lawn care tools clean and sanitized to prevent the spread of fungal spores.

Lawn fungus thrives in specific environmental conditions and can be triggered by various factors, including:

  • Excessive moisture from overwatering, heavy rainfall, or poor drainage
  • High humidity and warm temperatures
  • Compacted soil or a buildup of thatch
  • Improper mowing practices, such as cutting grass too short
  • Overuse or incorrect application of fertilizers

Understanding the factors that contribute to lawn fungus growth can help you take the necessary steps to prevent and treat fungal infections.

Will Lawn Fungus Go Away on Its Own?

In some cases, lawn fungus may resolve itself without intervention. This is especially true if the underlying cause is addressed (such as improving drainage issues, adjusting bad watering practices, or properly fertilizing your lawn).

Seasonal Lawn Disease Guide

To accurately identify the type of fungus affecting your lawn, it’s helpful to examine lawn fungus identification pictures. Below are pictures and descriptions of some of the common lawn fungus diseases in our area. For a more precise appraisal, you can consult with one of our lawn care professionals.

Brown Patch Fungus

Brown patch fungus, also known as large patch disease, is a declining turf condition caused by a single species of fungus, Rhizoctonia, and often occurs in mid-to-late summer when the weather is hot and humid — making conditions perfect for the fungus to thrive.

Dollar Spot Fungus

Dollar spot is caused by the fungus Clarireedia jacksonii (formerly Sclerotinia homoeocarpa). This disease affects highly managed turf types worldwide. It is characterized by small, round, straw colored spots that appear to be bleached.

Leaf Spot Fungus

Leaf spot / melting out is one of several Helminthosporium diseases which survive in thatch during periods that are unfavorable for disease development. These fungi are most active during periods of cool (60-65°F) and wet weather, but some are able to cause disease whenever temperatures are above freezing.

Red Thread Fungus

Red thread develops in circular or irregular patches from 4 inches to 2 feet in diameter. Affected leaves within these patches are tan or bleached-white in color. From a distance, the patches usually have a reddish appearance, due to the presence of thick, red strands of fungal growth emanating from the affected leaves. This fungus is able to cause disease at temperatures ranging from 40 to 80°F, but develops most rapidly at approximately 70°F. Red thread affects grass that is growing slowly for any  of the following reasons: inadequate lawn fertilization, drought stress, cool weather, low light intensity, excessive traffic, or many other pest or environmental stresses

Lawn Rust Fungus

There are around 8,000 named species of rust diseases, many of them host-specific. Rust does not usually kill its plant hosts, but can severely limit the growth of plants and their production of food for people. Because rust fungi are obligate parasites, they will only live on living plants. The rusts are amongst the most common fungal diseases of garden plants. Trees, shrubs, herbaceous and bedding plants, grasses, bulbs, fruit and vegetables can all be affected. 

Seeking Professional Help for Lawn Fungus Issues

Lawn fungus is a prevalent issue that can significantly affect the health and appearance of your lawn. The development of fungal diseases is influenced by various factors, including environmental conditions, lawn care practices, and the presence of pathogens. Identifying the type of fungus and understanding its causes are crucial steps in effectively treating and preventing lawn fungus.

Homemade solutions, such as baking soda and vinegar mixtures, can offer temporary relief but must be used with caution to avoid damaging your lawn. For sustainable lawn health, it is essential to adopt comprehensive lawn care practices. These include proper watering, mowing at the correct height, aerating, dethatching, fertilizing appropriately, and maintaining lawn hygiene. By addressing the root causes of fungal growth, such as excessive moisture, compaction, and improper fertilization, you can reduce the risk of fungal diseases.

While some types of lawn fungus may resolve on their own with the correction of underlying issues, consistent and correct lawn care practices are the best defense against fungal diseases. For persistent or severe problems, consulting with lawn care professionals can provide targeted treatments and strategies tailored to your lawn’s specific needs. By understanding and implementing these practices, you can maintain a healthy, vibrant lawn free from the detrimental effects of lawn fungus.


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