Your Neighborhood Lawn Care Provider.
The 2 Common Fungal Diseases Invading Maryland and Virginia Lawns
- On June 09 2025
Lawn fungal diseases aren't just a winter issue - they're a year-round hassle for homeowners. When there's moisture, there are fungal problems, especially during the warm Virginia and Maryland months. According to the University of Maryland Extension, red thread and brown patch are two of the most common lawn diseases in the state. Homeowners should be familiar with these two lawn diseases before they impact their lawns.
Common Diseases in Maryland and Virginia Lawns: Red Thread and Brown Patch
What makes these two diseases worthwhile to know? They're two of the most common diseases in Virginia and Maryland lawns. Red thread and brown patch are highly prevalent in the warmer months, causing aesthetic and health issues. Many conditions can encourage fungal issues to develop, including poor soil drainage, seasonal weather patterns, and soil infertility.
What is Red Thread Disease?
Caused by the fungus Laetisaria fuciformis, Red thread is a disease that primarily affects cool-season turfgrasses in the spring and fall. While unsightly, it's a cosmetic issue that doesn't affect your lawn's health. As the temperatures increase in the summer, the appearance of red thread will naturally disappear on its own. Our fertilizer treatments will grow out the disease and your weekly lawn mowing will remove all affected leaf blades.
How to Identify Red Thread Disease
The fungal disease is distinguishable from other infections by its color. Red thread creates reddish-pink, threadlike strands called stromata on the canopy of the turfgrass in two stages of development. The first stage develops thin strands within the turfgrass, and the second stage produces pink, wool-like mycelium. A more developed red thread fungal infection may also produce a pink gelatinous substance on the surface of turfgrass. Red thread is most visible in the morning in the presence of morning dew.
Conditions Promoting Red Thread Disease
Like most fungal infections, red thread thrives in damp lawns and cool-temperatures. It develops particularly in wet, cool climates like those in Maryland's spring and fall. These conditions create the ideal environment for the fungus to spread across turfgrass, especially when the grass is already stressed or undernourished.Environmental Conditions:
- Cool, wet weather (often during the spring or fall seasons)
- Shaded lawn areas with minimal sunlight
- Long periods of rain
Lawn Conditions:
- Susceptible turfgrass varieties
- Poor soil drainage
Managing Red Thread Disease
As previously mentioned, the visible effects of red thread disease will disappear as the temperatures increase. However, if the red thread is affecting your lawn repeatedly, following lawn care best practices can alleviate the severity of the disease. Applying a water-soluble nitrogen fertilizer can reduce the appearance of red thread by helping your grass outgrow the affected areas. For a more permanent solution, aerating and overseeding with a disease-resistant turfgrass type will naturally shield your lawn from future infections.
What is Brown Patch Disease?
Brown patch, or Rhizoctonia solani, is a common hot-weather disease that generally affects cool-season turfgrasses, especially tall fescue and perennial ryegrass, in wet summers. Unlike red thread disease, brown patch disease yields both cosmetic and health issues within lawns. Brown patch targets the grass blades and causes them to die back, leaving them brittle and yellow.
How to Identify Brown Patch Disease
Brown patch disease can be identified with a quick look and an up-close examination. From a broader view, brown patch appears as uneven, thin, yellow-brown areas of affected turfgrass. Occasionally, these patches may be encircled by a blue-black “smoke ring.” However, a closer look at individual grass blades reveals dark brown horizontal streaks and yellow, straw-like damage across the foliage. You may also notice fluffy, white mycelium on the grass's surface, indicating the presence of brown patch fungus.
Conditions Promoting Brown Patch Disease
The effects of brown patch disease are the most severe during hot, humid summers. Additionally, poorly maintained lawns with low-quality soil are also susceptible to brown patch infections. Under the right conditions, the disease can spread rapidly.Environmental Conditions:
- Temperatures above 65°F at night and 85°F during the daytime
- Dewey, damp mornings
- Warm, wet summer weather
Lawn Conditions:
- Susceptible turfgrass varieties
- Poor soil drainage
- Excessive thatch growth
Managing Brown Patch Disease
Left untreated, brown patch can affect your lawn, so managing it quickly is crucial. Best practices include always mowing with sharp blades, reducing blade tearing, and leaving the foliage vulnerable to infection. Additionally, water your lawn early in the day to allow grass blades to dry before evening, reducing humidity levels that favor fungal growth. The most effective and long-term method to manage brown patch disease is overseeding with disease-resistant turfgrass varieties.
Fall Aeration and Overseeding for Disease Resistance
Fall aeration and overseeding can prevent fungal diseases like red thread and brown patch from resurfacing. New seed varieties are more resistant to these types of lawn diseases each year. By introducing stronger, resistant turfgrass seed to an existing lawn, we can strengthen its defenses against infections without using fungicides.A fall aeration will lay the foundation for a supportive growth environment for new seeds. Aerating a fungus-prone lawn in the fall will improve drainage, boost air circulation, and allow new grass seeds to settle. Aeration should be followed by overseeding with an advanced disease-resistant seed blend to thicken the lawn and strengthen its immunity.
Aeration and overseeding should be every homeowner's first solution to fungal diseases, not fungicides! A combination of the two lawn care practices benefits your lawn by:
- Improving nutrient, air, and water movement
- Reducing soil compaction and improving drainage abilities
- Enhancing seed germination
