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Why Does My Lawn Look Like That? The Diseases that Are Ruining Your Lawn

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If you are a  homeowner, maintaining your lawn and keeping it green without lawn care services can be a frustrating challenge. Do you have brown spots appearing out of nowhere? Mushrooms popping up mysteriously? Or maybe some unsightly fungus? Any one of these could actually be a common lawn disease that plagues lawns across the US every year. Here are a few of the most common lawn diseases, how to identify them, and what can be done to treat them.

Brown Patch

Brown patch disease is a common fungal lawn disease found on most types of grass. Symptoms start to show in early spring for cooler grasses and late spring for warm grasses. Brown patch appears as a circle of thinned out, dead grass. Typically the border is darker with some patches of grass still living in the middle of the circle. Circle size can vary from a few inches to a few feet.

The good news about brown patch is that most grass can recover from it if treated properly. Proper fertilization can both help to prevent and fight brown patch disease. Additionally, avoiding overwatering your lawn or cutting the grass help to protect your grass from brown patches. If you have noticed brown patch disease, do not spread diseased lawn clippings around your yard after you mow. Instead, always throw these clippings away to prevent the fungus from spreading.

Summer Patch

Summer patch is similar in appearance to brown patch disease. However, summer patch is common primarily on Kentucky bluegrass. Summer patch can be more severe in that the areas affected are more prone to die when hot summer weather strikes.

Stressed lawns are more likely to suffer from summer patch. Fertilize properly, water in smaller doses but more frequently, and use a fungicide to prevent this from happening. If your lawn has fallen victim to summer patch, use a fungicide for treatment and overseed to get grass to grow back in the patchy areas.

Necrotic Ring Spot

Necrotic ring spots occur most commonly on bluegrass in cooler temperatures between 60 and 70 degrees Fahrenheit. The primary symptom of this fungal disease is that grass roots turn dark and black and appear rotten.

Treatment for necrotic ring spot is similar to treatment for summer patch. Because the soil is often overwatered, switch to watering your lawn in smaller amounts, but more frequently. Use a fungicide to supplement your irrigation treatment.

Fairy Rings

Fairy rings can occur on a variety of grass types in a variety of climates. Fairy rings can also appear in three different ways — a dry spot, a lush spot, or a ring of mushrooms. Fairy rings are caused by a fungus in the soil. When the fungus eats the nutrients in one condensed area, it begins to spread to an outer layer, causing a ring to appear.

Treatment for fairy rings will vary depending on the type you are experiencing. Typically, better watering practices and fungicides can help to cure your lawn. However, if may be necessary to entirely replace the top of your soil in a fairy ring’s surrounding area.

Pythium Blight

Unlike many of the other diseases on this list, pythium blight occurs most commonly in warm, wet climates and seasons. Pythium blight also differs in that it has no consistent shape or size in which it appears.

Because of the humid climate it occurs in, pythium blight is identified by its white, cobweb-like mold that covers the turf. The best treatments for pythium blight are aeration, proper fertilization, and lighter irrigation.

Ascochyta Leaf Blight

Ascochyta leaf blight is a sneaky fungus that overwinters in your turf’s thatch. The fungal spores are then dispersed with water and grass clippings from lawn mowers. Ascochyta leaf blight most commonly occurs in hot weather climates.

You can prevent ascochyta leaf blight by removing thatch from your lawn as part of your spring lawn preparation so that there is nowhere for the fungus to grow. If you have noticed ascochyta leaf blight, you can combat it with fertilizer, fungicide, and by managing your irrigation to prevent watering too much or too little.

Pink and Gray Snow Mold

Pink and gray snow molds are unfortunate fungi that affect cooler grasses at a variety of temperatures. These molds are most commonly found on golf courses with young, long grass. Pink and gray snow molds oversummer, meaning that they lay dormant during the summer and appear in the winter.

Both molds have pathogens that live in thatch. Similar to ascochyta leaf blight, the spores are spread via water and glass clippings. One way to prevent pink and gray snow mold is to mow your lawn as late in the fall as you can to prevent snow from weighing down longer grass and spreading the disease. Fungicides help to cure a lawn suffering from either pink or gray snow mold.

Slime Mold

Slime mold is an unsightly disease that occurs in moist conditions, appearing as gray and yellow slime on blades of grass. Fortunately, slime mold is primarily an aesthetic issue and does not pose any real threat to your lawn. Most slime mold will appear and disappear within the span of just a few weeks, so serious treatment is typically unnecessary.

Red Thread

Red thread appears on a lawn as circular patches that are either tan or pink. This disease is most likely to develop in cooler temperatures on malnourished grass that is in poor health, or “stressed.”

Red thread is a disease that overwinters and then begins displaying symptoms in the spring. Proper fertilizing practices throughout the year helps to prevent and control this lawn disease.

Lawn Rust

Although they may have similar sounding names, red thread and lawn dust are two different lawn diseases. Red thread is an issue that primarily occurs at the roots of your lawn. Lawn rust appears on the tips of the blades. Most grass types are susceptible to lawn rust during the growing season.

Lawn rust appears as orange specks on grass blades. These orange specks are small fungal spores. Lawn rust is not inherently dangerous to your lawn’s health, but it can be a symptom of a lawn that is not being well taken care of. Lawn rust is treated by mowing to remove the infected tips, and using fertilizer and fungicides.


Cyanobacteria is a dark algae that develops on thatch or thinned grass. This bacteria is most common on shaded areas of lawns that do not receive adequate sunlight and may be overwatered. It can occur in any climate, on any type of grass.

If you love having your trees for shade or if your grass is shaded often by surrounding walls or buildings, cyanobacteria can be difficult to prevent. However, aerating your lawn as well as keeping your grass a little longer and using a fungicide can help to keep cyanobacteria away.

Now that you know a few of the most common lawn diseases, you can use the proper tools and methods to arm your lawn against them. For extra help or advice with Orem lawn care, contact Edge today.

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