Noticing your lawn start to thin out or grass blades developing tiny dark spots? That could be more than just a cosmetic issue — it might be a fungal disease known as Leaf Spot. While it often starts small, Leaf Spot can spread quickly under the right conditions, leaving your lawn looking patchy, stressed, and unhealthy.

What Is Leaf Spot?

Leaf Spot is a common lawn disease caused by a group of fungi including Bipolaris, Drechslera, and Helminthosporium. It primarily affects cool-season grasses such as Kentucky bluegrass, perennial ryegrass, and fine fescue.

The disease starts with small lesions or “spots” on individual grass blades, but if environmental conditions are right and it’s left untreated, it can lead to more serious damage. In severe cases, the grass crown becomes infected, and the entire plant may die — this is known as the melting out phase of the disease.

What Causes Leaf Spot?

• Cool to warm temperatures (60–85°F)
• High humidity or extended periods of moisture
• Heavy dew, frequent rain, or watering in the evening
• Excessive nitrogen fertilization
• Scalping or mowing too short
• Poor air circulation and compacted soil

What Does Leaf Spot Look Like?

• Small brown, purple, or black lesions on grass blades
• Lesions often have a light tan center with a dark border
• Tips may turn straw-colored or shrivel
• Grass dies from the tip downward
• Patchy thinning or browning in advanced stages
• In severe cases, complete plant death during melting out

How to Prevent and Treat Leaf Spot

• Mow High: Set your mower at 3–4 inches to reduce stress on the lawn.
• Water Smart: Water early in the morning, deeply but infrequently.
• Improve Airflow: Aerate to reduce compaction and promote circulation.
• Fertilize Properly: Avoid heavy spring nitrogen—balance is key.
• Apply Fungicide: Use professionally applied fungicide if conditions favor disease spread.

Can Leaf Spot Kill Your Lawn?

Yes. If it progresses to the melting-out phase, the entire grass plant can die, leading to bare patches that may need seeding or sod.

Let Us Help You Protect Your Lawn

At My Fertilizing Company, we know how to spot Leaf Spot early — and we know how to prevent it before it becomes a problem. Whether it’s part of our fungicide treatment plan or a recommendation for better cultural practices, we’ll create a strategy tailored to your lawn’s needs.

Concerned about spots on your lawn? Contact us today for a free lawn evaluation.