800.845.0580

We offer 100% Risk Free Guarantee! -Learn More

12 Common Lawn Diseases

Posted on October 17, 2024 by Lawn Doctor

get quote username

Call 800-529-6362 or fill out the form below for your Free Lawn Evaluation!

First Name
Last Name
Email Address
Zip code
Phone
Street Address
Request A Quote

Just like your body, your lawn can become ill. There are a number of lawn diseases that can affect your lawn or yard. Most lawn diseases are caused by fungi, which infect both warm- and cool-season grass plants. We’re here to help you learn all you can about lawn disease control so you can take great care of your turfgrass.

Common Lawn Diseases

Common lawn diseases, such as dollar spot and red thread, often look worse than they are. Although these diseases destroy grass blades, they can be treated before the symptoms become severe enough to kill your plants. Fertilizer is the key to helping your lawn recover from these spring diseases.

Soil-borne diseases, such as brown patch and summer patch, can cause extensive damage to warm and cool season grass types. Brown patch is most severe on St. Augustine and tall fescue lawns, while summer patch primarily affects Kentucky bluegrass lawns. The majority of these diseases are active in the spring and can weaken your lawn.  Also, summer heat conditions can aggravate the symptoms of some diseases.

During cooler weather, snow mold develops in wet environments. Snow mold can lead to crown and root rot under winter snow. To find out if you have snow mold, look for patchy, gray areas after long periods of covered snow. Another common issue is spring dead spots. This is characterized by circular patches of sunken turf. These dead patches can persist well into the summer, and in some cases, your lawn won’t recover until the disease becomes dormant in the fall.

How to Prevent Yard and Lawn Diseases

Prevention is key to stopping yard and lawn diseases. A healthy grass plant is the best defense against lawn disease.  Proper mowing, watering and fertilizing practices are extremely important for a healthy lawn.

  • Mow at the proper height. Never cut more than one-third of the grass blade each time you mow.
  • Water the lawn 1 inch per week. It’s best to water in the morning.
  • Fertilize cool-season grasses with nitrogen in the spring and fall.
  • In the summer, fertilize warm-season turf with nitrogen.

As the weather changes, the fungi will run its course, and your lawn should gradually recover.

We Treat All Common Lawn Diseases

Our lawn care experts can diagnose and treat all common types of lawn diseases, including:

Dollar Spot 

Dollar spot is a lawn disease that most commonly occurs in the summer and early autumn due to the warm, wet conditions at those times of year. Lawns that are shaded and not exposed to wind are more likely to develop dollar spot because they stay damp for longer after rainfall. Poor drainage can also increase the risk of your lawn developing this disease.

To prevent dollar spot, don’t water your lawn more than once or twice a week. Aerate your lawn regularly, and test for pH balance if you have any concerns. Finally, make sure your lawnmower has sharp blades to avoid damaging or bruising the grass. Clean, crisp cuts help protect your lawn from not only dollar spot, but other diseases as well.

Brown Patch 

Brown patch is a fungal disease most commonly seen during hot, humid weather. It causes circular brown patches that can be up to several feet in diameter. Before the grass turns brown, it may develop a purple/green hue. While it’s often possible to treat brown patch with basic lawn management, severe infections may require fungicide treatments to prevent excessive damage.

To prevent brown patch lawn disease, follow best practices to maintain a healthy turf. This means taking care not to overfertilize your lawn and making sure it’s properly aerated. Water your lawn in the early hours of the morning, and be sure not to overwater. Prune shrubs to ensure your lawn gets adequate sunlight.

Leaf Spot 

There are several varieties of leaf spot, and the symptoms vary depending on the exact pathogen infecting the leaves. In most cases, you’ll see affected leaves turn yellow or pale and develop lesions. In some cases, the leaves will also show signs of withering and drought stress. All species of grass are susceptible to this condition.

Leaf spot is another infection that tends to occur in hot, humid weather. It’s more likely to happen if you cut your lawn to a lower height than recommended for that species of grass. To treat this infection, remove excess thatch, make sure your lawn is properly aerated and allow the grass to grow taller. Make sure your lawnmower has properly sharpened blades to help prevent further damage to the leaves.

Pythium

Pythium is a fungal disease that can affect most mature turf species, both cool-season and warm-season. It’s known by several names, including spot blight, cottony blight and grease spot. The fungus thrives in hot, humid conditions and is particularly common in regions where nighttime temperatures are high and humidity of over 90% is commonplace.

You can prevent pythium by watering your lawn deeply but infrequently, aerating regularly and dethatching to help promote moisture drainage. Aim to keep your soil at a neutral pH level, and use a slow-release fertilizer to maintain adequate nitrogen levels throughout the summer. If an infection does occur, use a broad-spectrum fungicide to treat it, then reseed the affected areas to promote healthy lawn growth. If your lawn is infected with pythium, clean your lawnmower after each use to prevent the disease from spreading to other parts of the lawn.

Red Thread 

Another fungal infection that occurs during the summer and autumn, red thread typically impacts lawns deficient in nitrogen. It causes patches of brown turf and can be identified by the characteristic red gelatinous, thread-like growths of fungus in those affected areas.

Red thread doesn’t usually kill the grass, so the impacted patches should grow back once the fungus is treated. Antifungal treatments for red thread are available, but it’s generally recommended to try nonchemical treatment options first. Removing excess thatch can help increase aeration, and treating the affected patches with nitrogen can often help control the fungus. It’s best to seek advice before adding nitrogen because excessive nitrogen can have undesirable side effects, such as increasing the risk of snow mold.

Rust 

Rust diseases are caused by pathogens that infect the leaves of the grass and can kill them but won’t usually kill the entire plant. Unlike many other fungi that cause lawn infections, the fungi responsible for rust diseases can’t live in the soil and won’t decompose thatch. It’s merely an opportunistic pathogen.

You can spot a rust infection by looking for rusty-colored or black powder on your turf leaves in autumn. Once the disease sets in, it will cause the affected leaves to turn yellow. Lawns that are underfertilized are more susceptible to this kind of infection, and the best way to control or prevent it is to ensure your lawn is properly fertilized and you mow the grass regularly. Fungicides aren’t recommended for the treatment of turf rust, but if you practice proper lawn care, you should be able to control the disease without them.

Snow Mold 

If you see brown patches on your lawn in the autumn or winter, there’s a possibility they’re caused by snow mold. This turf disease is common during mild winters and is particularly noticeable during thaws of snow, hence the name. Patches of snow mold can be up to a foot in diameter and can occur close together, affecting quite large areas.

You can manage snow mold by taking care not to overfertilize your lawn during the autumn months and paying attention to aeration and drainage. If your lawn is susceptible to snow mold, consider using a switch or cane to remove heavy dew to prevent the mold from taking hold. Consult a lawn care company about the use of fungicides if you find it difficult to eradicate the condition.

Summer Patch 

Poa patch, also known as summer patch, is a lawn disease that affects the kind of turf commonly seen on golf courses and athletic fields. It can also impact some varieties of home lawn turf. The disease attacks the root and crown of the grass, causing it to become yellow, then brown as the afflicted plants die off. In some areas, the patches of dead grass may be recolonized by other varieties of grass that are less susceptible to the disease.

Taking steps to lower soil pH, improve aeration and increase drainage can help strengthen the roots of the plants and stop the disease from taking hold. Overseeding turf with a perennial ryegrass can make the issue less noticeable and is a common strategy on golf courses and athletic pitches.

Powdery Mildew 

Kentucky bluegrass and perennial ryegrasses are particularly susceptible to powdery mildew, but it can affect other grass types as well. This lawn disease looks like a white powdery coating that accumulates on the blades of your turfgrass. Over time, the diseased grass spreads to form white or gray spots on the lawn.

The infection is caused by an obligate parasite known as Erysiphe graminis. This fungus can only survive by living on a host plant. The best grass disease treatment for powdery mildew is to aerate your lawn and prune back any trees and shrubs that are nearby to improve airflow. The fungus thrives in dark, humid areas, so pruning trees to reduce shade is helpful.

Fairy Ring 

Fairy rings are rings of fungi that live in the roots of your turf. In many cases, the fungi cause no noticeable harm and don’t change the appearance of the grass, although sometimes you might notice a ring of dead grass. Toward the end of summer, a crop of toadstools may appear. These toadstools produce spores that can spread the infection to other areas of the lawn.

To clear a fairy ring infection, you may need to remove the affected section of turf and replace it with fresh soil, then reseed it. Alternatively, professional-grade fungicides can eradicate the fungus.

Leaf Blight

Leaf blight is caused by a fungus that attacks the leaves of your turf. In most cases, the infection won’t cause long-lasting damage to your grass. However, if your lawn is starved of nutrients and you have a persistent spell of wet weather, the infection could become severe enough to cause lasting damage.

To prevent a leaf blight infection, water your lawn in the morning or early afternoon so it dries before the sun sets. Mow your lawn regularly, and fertilize it using a fertilizer that is suitable for the current season.

Slime Mold 

Unlike most of the other infections on this list, slime mold is neither a fungus nor a disease. In fact, most slime mold isn’t even harmful to your lawn; it’s just unsightly. Slime molds are single-celled organisms that use grass stems to support the growth of their spore masses when the spores are moving together to search for food.

There are many different types of slime mold and many different colors too. The spores look slimy (which is where the name comes from) while they’re fruiting. They then disperse in the wind. Slime mold can be good for your grass, but if you find it unsightly, you can always wash it away with a power washer. There’s no need to use a fungicide because these organisms won’t be affected by them, and the fungicide could even harm your grass more than the slime mold does.

If you’re having issues with your lawn, contact Lawn Doctor today. Our skilled lawn care experts will get your lawn looking lush and green once again. 

Tired of the tedious and grueling work of maintaining your lawn?

Contact Lawn Doctor to help care for your lawn when you can’t.

Related Articles

Weed Control in My Yard

After years of finding the perfect home, you just want...

Image of a shed in autumn

How to Winterize Lawn Mowers: All You Need To Know

If you’re asking yourself “what do I do with my...

Footer username
Footer First Name
Footer Last Name
Footer Zip code
Footer Phone
Footer Email Address
Footer Street Address
Footer Request A Quote