A glorious green lawn is a prominent feature of the home, but lawn diseases can ruin this perfect emerald expanse. Common grass diseases often cause bald patches, discolored blades, ringlets and other abnormalities.
Turf disease control should begin in early spring just before new growth appears with a second application in the fall which will further protect your turf. Lawn diseases can be viral, bacterial or fungal, although viral diseases are rare in turf. These problems may come from improper lawn careenvironmental conditions or different pathogens. There are specific treatments for each, but the first step is to determine which problem is affecting your lawn.
I’ll walk you through the most common lawn diseases that plague home landscapes. Next, I’ll share my top tips on how to prevent and deal with these issues.
Common lawn diseases
Sometimes improper lawn care is responsible for unsightly lawns, but it is often caused by a large number of pathogens. Disease recognition is the key to turfgrass disease control.
Turf disease treatment is relatively specific to the type of pathogen, such as using different fungicides for various fungal lawn diseases. Likewise, bactericides work on most but not all bacterial diseases.
Here are the most common lawn diseases and how to determine which one is affecting your yard.
1. Brown patch
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Brown patch it may resemble the damage caused by dogs, but the irregular, rounded dead patch consists of blades with black lesions that have darker edges. Over time, rounded patches can expand to larger areas.
In the morning dew, you can notice the purple to gray spider web-like growth on top of the grass blades. This is the fungus that causes the disease. It is more prevalent in wet weather cool season greens. Fungal growth can almost completely cover the lawn area if left untreated.
2. Dollar Spot
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Spot in dollars appears as small, rounded patches of bleached grass. They are the size of a silver dollar, which leads to the common name of this disease. As the disease progresses, the spots begin to blend into each other.
This disease is also caused by a fungus, which appears early in the morning as silvery-white threads on the grass blades. The fungus favors warm, humid conditions and is easily spread by walking on your lawn or with mechanical equipment. Large areas of grass can die if left untreated.
3. Fairy Ring
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Although the name is rather cute, a fairy ring is a serious disease that results in irregular areas bordered by darker green. When conditions are very wet, mushrooms can also appear in the darker green outline.
Symptoms of the disease appear in early spring when cool, wet weather feeds the fungus. The fungus starts in a central spot and radiates outward, leaving weak grass in the center that can become susceptible to other diseases.
4. Melting
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Melting is a disease that occurs when the weather is wet and cool. It can cause very large patches of yellow grass with sparse blade growth and loose plant material. If you get a rake in the accumulation of straw which sometimes causes this disease, large clumps will readily come out. Although cool-season grasses are most commonly affected, it can also occur in warm season grass varieties.
5. Leaf spot
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Many viruses and bacteria can cause it leaf spotbut it can also be fungal. Grass blades will develop small elongated brown spots with reddish or purple borders. The overall appearance of the lawn may disappear on the site. Leaf spot is more prevalent in the summer and can cause entire sections of the lawn to die.
6. Measles
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powdery mildew is a fungus that affects many types of plants. It is very recognizable due to the white powdery residue on the leaf blades. The fungus feeds on plant tissue and causes damage, killing the leaf over time.
In significant cases of powdery mildew, the leaves are reduced, the area is patchy and the overall health of the lawn is impaired. Mildew prefers warm, humid conditions.
7. Red thread
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Also known as pink patchred thread is a fungal disease that causes thread-like growth on the tips of leaf blades in red and coral shades. It can be complicated to control and can appear overnight. Leaf blades will decrease in number and the lawn will become patchy.
8. Slime mold
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Unsavory in appearance as well as in name, slime mold is a moist, smooth mold that covers the leaf blades in various colors. It can also fruit and develop tiny growth balls on the grass leaves.
Slime mold is not harmful to the grass itself, but it does add an unattractive appearance to the lawn. It occurs when there is too much organic matter in the soil and conditions are warm and wet.
9. Rust
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Slag is a fungal disease that causes orange and brown lesions on leaf blades. The leaves die and the resulting turf becomes patchy and sparse. It is most common in late summer to fall when there is plenty of moisture and warmth. The fungus lives in the thatch and appears when the right conditions exist. Spores can be carried to other areas of the lawn by shoes and tools.
How to prevent lawn diseases
The way you water, fertilize and mow your lawn it can affect the health of your grass beneficially or negatively. The timing of these activities is also important. Most of the common lawn diseases are caused by fungi.
Fungi require moisture to thrive. Some prefer cool, moist locations, while others need warmer temperatures. If you water your lawn when grass blades cannot dry in time, fungi can take over. Early morning is the best time to water.
Too much lubricationr creates a nutrient-rich environment where fungi can thrive. A lawn grown in excessive shade is prone to fungal diseases, as are lawns with thick thatch. The height at which you cut can also contribute to disease. Only remove a third of the length of the blade each time you cut.
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How to control lawn diseases
- Water your lawn in the morning.
- Mow your lawn when thatch is greater than 0.5 inches (1.27 cm) to prevent excessive moisture build-up, lack of oxygen, and nutrient density that enhance pathogens. If thatch is a common problem for you, consider a dethatcher like this one from Amazon so you can solve this issue yourself.
- Aerate your lawn if the soil is compacted to encourage water infiltration, nutrient movement, aeration and the creation of a healthy disease-resistant turf. You can hire professionals to ventilate or do it yourself with a home lawn aerator like this one from Amazon.
- Fight the weeds which can steal water and nutrients from the grass and lead to grass that is more susceptible to disease.
- Only cut a third of the height from your lawn at a time to avoid damaging the lawn and keep the blades tall enough to retain moisture. This will help avoid the need for excessive watering.
- Perform a soil test to determine the amounts of nutrients in the soil for more precise feeding of the lawn. Many soil tests can also determine soil pH, such as this one from Amazon. Excessively acidic soils favor many fungi while alkaline soil favors other diseases. Aim for a pH of 6.0-7.0.
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When to bring in a professional
If you simply don’t have the time or resources to do regular yard maintenance, then it’s time to do it call a landscaping professional. But with a maintenance and chore schedule, most lawn diseases are easy to avoid with the simple tips above. If your lawn is new to you or has been poorly managed for some time, bring in professionals to bring the lawn back to health and then take it from there.
Frequently Asked Questions
What is the most common grass disease?
The most common disease will depend on the variety of your lawn and where it grows. Southern gardeners will find many different problems than Northern lawn growers. Dollar spot, leaf blight and brown spot are very common.
How do you know if you have lawn fungus?
You may need to get to eye level with your lawn to diagnose problems. Visual signs such as browning or yellowing, grass spots and fainting are just some of the more common signs of fungal disease. If the leaf blade itself has spots or necrosis, this can be another sign.
