Sure, weeds are easy to spot in your Greater Chicago commercial lawn. They stick out with their nasty, spiky, mismatched shapes that look markedly different from your nice, even, thick lawn.

But lawn diseases are another story altogether. The right weather conditions can bring them about without warning. Most of the diseases out there resemble patchy or irregularly shaped spots in your lawn, which are symptoms that are hard to distinguish from other problems. For all you know, those marks could be from drought.

If you're in the business of maintaining commercial lawns in the Windy City, you know that keeping those green spaces looking pristine is no easy task.From bustling office parks to bustling downtown areas, Chicago's commercial landscapes face their fair share of challenges, including pesky lawn problems like diseases. But fear not. Let’s dive into the world of common lawn diseases found in Chicago's commercial lawns and how to tackle them head-on.

Signs of Lawn Disease

Lawn diseases tend to show up in your lawn in a very aesthetically unpleasing way. They ruin your perfect commercial lawn picture with spots and patches.

Before we jump into specific common lawn diseases, let's talk about the telltale signs that your commercial lawn may be suffering from a disease.

Keep an eye out for:

  • Brown or yellow patches: If your once-green lawn is starting to look a bit patchy and discolored, it could be a sign of disease.
  • Thin or sparse grass: Healthy lawns are lush and full, so if you notice thinning or bare spots, it's time to investigate.
  • Unusual growth patterns: Diseases can cause grass to grow in strange, clumpy patterns or even produce fungal growths like mushrooms.
  • Visible lesions or spots: Some diseases manifest as lesions or spots on the blades of grass.

How to Identify a Lawn Disease

Some common lawn diseases in Greater Chicago attack when certain environmental conditions collide.

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Lawn diseases may be tough to recognize, but here are a few common ones that pop up in Greater Chicago you should watch out for, as well as some insight into what causes them, and how to fight them.

1. Red Thread

Red thread lawn disease is a common fungal infection that can turn a once-lush green lawn into a patchy, red-tinged eyesore. It typically thrives in cool, moist conditions, making it a frequent visitor to lawns in temperate climates like Chicago's.

The disease is caused by the fungus Laetisaria fuciformis, which forms distinctive red or pink threads on the grass blades.


To combat red thread lawn disease, it's essential to improve airflow and reduce moisture levels in the affected area. Achieve this by pruning overhanging branches, aerating the lawn to alleviate compaction, and adjusting watering practices to avoid creating overly damp conditions. Additionally, applying a fungicide specifically formulated to target red thread can help suppress fungal growth and restore your commercial lawn's vibrant green appearance.

Regular maintenance practices, such as proper mowing and fertilization, can also aid in preventing future outbreaks of this troublesome disease.

2. Rust

Rust lawn disease is a fungal infection that can leave your once-lush green lawn looking dull and rusty. It's caused by various fungal species, which thrive in warm, humid conditions often found in late summer and early fall.

The disease manifests as small, yellow to orange-colored pustules on the grass blades, resembling rust spots.

Lawn Rust (puccinia) CC

To address rust lawn disease, it's crucial to improve air circulation and reduce moisture levels in the affected area. Do this by pruning back overgrown vegetation, aerating the lawn to promote better drainage, and adjusting watering practices to avoid excessive moisture buildup.

Additionally, regular lawn maintenance practices, such as mowing at the appropriate height and fertilizing as needed, can help prevent future outbreaks of rust disease.

3. Powdery Mildew

Powdery mildew is a common lawn disease that can wreak havoc on lawns, leaving behind a powdery white coating on the grass blades and foliage. This unsightly disease is caused by various fungal species that thrive in warm, humid conditions with poor air circulation.

Powdery mildew typically occurs during periods of high humidity or when temperatures are mild, making it a frequent visitor to lawns in temperate climates like Greater Chicago's.

Powdery Mildew CC

To combat powdery mildew, it's essential to improve air circulation and reduce humidity levels in the affected area by pruning back overgrown vegetation and thinning out dense areas of grass. To prevent this disease, you also want to water your commercial lawn early in the day so it has time to dry out. Also, water shaded areas infrequently but deeply.

4. Dollar Spot

Dollar spot lawn disease is a common affliction that can turn your once-pristine commercial lawn into a patchy, discolored landscape dotted with small, silver-dollar-sized dead patches. Dollar spot thrives in warm, humid conditions, often making its appearance during the transition from spring to summer or in the early fall.

This pesky disease is caused by a fungus that spreads through airborne spores and can quickly colonize susceptible grass species like Kentucky bluegrass.

Dollar Spot (sclerotinia homoeocarpa) CC

To combat dollar spot, it's essential to maintain proper lawn health and vigor. This includes regular watering in the early morning hours to prevent prolonged leaf wetness, as well as adequate fertilization to promote strong root growth and resilience.

Additionally, improving air circulation by pruning back overgrown vegetation and mowing at the appropriate height can help prevent the spread of the disease. Applying fungicides labeled for dollar spot control can also be effective in suppressing fungal growth.

5. Brown Patch

Brown patch lawn disease is a frustrating fungal infection that can wreak havoc on your commercial lawn, causing circular patches of brown, dead grass to appear seemingly overnight.

Brown patch thrives in warm, humid conditions, often making its presence known during the hot, sticky days of summer. This troublesome disease is caused by the fungus Rhizoctonia solani, which spreads rapidly through grass blades and can quickly take hold in susceptible turfgrass species.

Brown Patch (Rhizoctonia solani) CC

To combat brown patch, it's crucial to implement proper commercial lawn care practices. This includes watering deeply but infrequently to avoid creating overly damp conditions that encourage fungal growth, as well as ensuring adequate airflow and sunlight penetration by pruning back overgrown vegetation and thinning out dense areas of grass.

Additionally, applying fungicides specifically formulated for brown patch control can help suppress fungal growth. Regular lawn maintenance, such as proper mowing and fertilization, is also essential in preventing future outbreaks of brown patch.

Get Rid of Lawn Diseases in Your Greater Chicago Commercial Lawn

You might be asking yourself, “What’s wrong with my commercial lawn?” And the answer could be a common lawn problem or disease.

Now that you know more about some of the most common lawn diseases, you might be able to identify some of the strange spots you’re seeing, as well as make a list of what you need to do to better manage them.

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In addition to boosting overall lawn health with fertilization, aeration, proper watering, and mowing, you might still find you have some spots that are more disease-prone than others. This is totally normal.

In fact, if you have places that have the right disease conditions frequently, your disease pressure will be higher. For instance, places that have shade most of the mornings and only a bit of sun in the evenings don’t get a chance to dry out or cool, so they go into the evening with more humidity than other locations. This is a recipe for diseases to spread.

If you notice spots that could be diseased even after improving your lawn with proper maintenance, you might consider calling KD Landscape. We can tell you what’s really going on in your lawn and offer some lawn care suggestions to get that green, thick grass back.

Are lawn diseases keeping you from having a commercial lawn you can be proud of? We’d love to learn more. Get started today with a free quote. Together, we’ll prepare a customized plan for your Greater Chicago commercial landscape that leads you to the best choice for you and your property.

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Image Sources | Red Thread, Rust, Powdery Mildew, Dollar Spot, Brown Patch