Identifying and Treating Common Lawn Diseases
After all the hard work of mowing and watering, seeing strange brown circles, yellowing patches, or fuzzy spots on your lawn can be incredibly frustrating. Most of these issues are caused by common fungal diseases, which are especially prevalent in Central Virginia thanks to our high heat and humidity.
These diseases can spread quickly if left untreated, but the first step is a correct diagnosis. This guide will help you identify the most common culprits. Keep in mind, a strong, healthy lawn is the best defense. To learn how to build that strong foundation, be sure to visit our main Lawn Care 101: Your Ultimate Guide to a Lush, Healthy Yard.
The #1 Culprit in Virginia: Brown Patch
This is, by far, the most common disease we see in our area, especially on Tall Fescue lawns.
What It Looks Like: Brown Patch appears as circular or irregular patches of brown, tan, or yellowing grass that can range from a few inches to several feet wide.
Key Identifier: The most telling sign is a dark, grayish-black "smoke ring" that borders the patch, which is most visible in the early morning when there's dew on the grass.
When It Appears: It's a summer disease. It thrives in high temperatures (80-90°F) and high humidity, especially when the lawn stays wet for long periods (like from watering at night).
The Cobweb-Like Disease: Dollar Spot
Dollar Spot is another very common disease, and its appearance is distinct.
What It Looks Like: It starts as small, silver-dollar-sized, straw-colored circles on the lawn. If left unchecked, these small spots can merge into large, irregular, blighted areas.
Key Identifier: In the early morning dew, you will often see white, "cobweb-like" mycelium (the body of the fungus) stretching between the grass blades within the affected spot.
When It Appears: Dollar Spot is most active in the spring and fall. It's often a sign that the lawn is under-fertilized and lacking nitrogen.
The Pink/Red-Tinged Grass: Red Thread
This disease is easy to spot thanks to its unique color.
What It LooksZ Like: From a distance, you'll see small, irregular, pinkish-red patches on the lawn. Upon closer inspection, you will see the grass blades are being covered by red or pink "threads" (the fungal growth), which can look like tiny antlers on the tips of the blades.
When It Appears: Red Thread is a cool-weather disease, most common during wet and humid spring or fall days. Like Dollar Spot, it is a strong indicator that your lawn is deficient in nitrogen.
What Causes Lawn Diseases?
Fungus is almost always present, but it only takes over and becomes a "disease" when the conditions are right. Most lawn diseases are a symptom of an underlying stressor or poor maintenance habit.
Watering at Night: This is the #1 cause. Watering in the evening leaves the grass blades wet for 10-12 hours, creating a perfect, humid environment for fungus to thrive. (Always water in the early morning!)
Dull Mower Blades: A dull blade tears and shreds the grass, creating a large, jagged wound that is an easy entry point for disease. A sharp blade makes a clean cut that heals quickly.
Compacted Soil: Dense, clay soil (common in our area) holds too much water at the surface and prevents airflow, promoting fungal growth.
Improper Fertilizing: Too much nitrogen in the summer can cause weak, "sugary" growth that is very susceptible to Brown Patch. Too little nitrogen can lead to Dollar Spot and Red Thread.
Let the Pros Handle It
Identifying the specific fungus attacking your lawn can be difficult, and the "cure" (a fungicide) must be applied correctly to be effective. Applying the wrong product or at the wrong time is a waste of money and won't solve the underlying problem.
If you're in the Central Virginia area and are tired of fighting brown patches, Mr. B's Lawn & Garden Care can help. We can correctly diagnose the issue, apply professional-grade treatments, and—most importantly—help you correct the underlying conditions to prevent it from coming back.