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Understanding and Preventing Take-All Root Rot

Maintaining a vibrant, healthy lawn is a top priority for many Texans who take pride in their outdoor spaces. However, for those with St. Augustine, Bermuda, or Zoysia grass, there’s a lurking threat: take-all root rot (TARR). This fungal disease is often found in warm-season lawns across the Lone Star State and causes unsightly patches and turf decline.

In this guide, we’ll explore the causes, symptoms, and most importantly, effective strategies for the prevention and treatment of TARR. Let’s ensure your lawn stays green, lush, and thriving all season long.

What is Take All Root Rot (TARR)?

Take-all root rot (TARR) is a fungal disease primarily affecting warm-season lawns in Texas. St. Augustine, Zoysia, and Bermuda grass are common targets. It is even referred to as “bermudagrass decline” because of its prevalence in Bermuda grass.

The culprit behind the demise of warm-season lawns is Gaeumannomyces graminis var. graminis. This fungus thrives in thatch, which comprises plant roots, stolons (horizontal shoots), and decomposing plant material.

Although the fungus can produce spores, it primarily spreads through roots and stolons. TARR isn’t typically transmitted by mowers or foot traffic. Instead, it’s more likely to spread when infected grass, thatch, or soil is relocated.

This fungus is found across much of Texas and can be sneaky because it sometimes lurks in lawns that otherwise look healthy. However, knowing the common symptoms can help you identify TARR.

Environmental Conditions That Lead to Take-All Root Tot

TARR is most prevalent during the spring and fall months in Texas due to specific environmental conditions:

  • High humidity: Above-average rainfall in the past winter and spring increases soil moisture, creating a humid environment ideal for fungal growth.
  • Mild temperatures: The optimal soil temperature range for TARR development is approximately 77° to 85° Fahrenheit. Spring and fall temperatures in Texas typically fall within this range, providing favorable conditions for the fungus.
  • Soil pH: Alkaline soils with pH levels above 6.5 promote TARR development, creating an environment where the fungus can flourish.
  • Improper mowing height: Mowing the grass too short can stress the turf and weaken its natural defenses against diseases like TARR.
  • Excessive thatch buildup: Thatch accumulation creates a hospitable environment for TARR-causing fungi to thrive.

Understanding these conditions is crucial for homeowners to take proactive steps to prevent TARR.

How do I know if my lawn has it?

For the average gardener, distinguishing TARR from other common diseases that cause turf to turn yellow or brown can be challenging. To the untrained eye, TARR may resemble grey leaf spot, chinch bug damage, or brown patch. Knowing the specific signs to look for will better equip you to make an informed diagnosis.

Signs & Symptoms of Take-All Root Rot

The first indicator of TARR is the presence of yellow-brown patches on the turf. Take a few grass blades and closely observe them; you’ll notice that the tips appear almost neon yellow. The unique yellowing of the tips distinguishes TARR from other fungal diseases that are similar in appearance.

Southern Botanical agronomist Tyler Breed emphasizes, “The yellowing of the grass is crucial because it’s distinct from brown patch, where different types of fungus cause orange blades.”

The areas of yellow and brown turf will gradually expand, but ideally, you want to treat the disease before it spreads. To check for TARR, you can pull the affected grass from the ground and examine the roots.

Healthy roots should be pearly white, while infected roots will appear greyish-black once the soil is cleaned off. Additionally, the root zone may be overly saturated. Thinning grass is another indicator to look out for. The below shows a sample of sympton development from a st augustine lawn.

Identifying Take All Root Rot

If your lawn shows signs of TARR, it is important to identify it promptly. Identifying it quickly means you can treat it before it spreads further.

The first indicator of TARR is the presence of yellow and brown patches on the turf. Take a few grass blades and closely observe them; you’ll notice that the tips appear almost neon yellow. The unique yellowing of the tips distinguishes TARR from other fungal diseases like grey leaf spot or chinch bug damage, which share a similar appearance.

Since TARR is a fungal disease that spreads through soil, a soil sample can be sent to a lab for testing. Though this may take up to a few weeks, the results will show whether you have TARR or a different issue.

Treatment & Prevention

An array of treatment and preventative measures are available against TARR. Prevention is always the best defense, but if you notice symptoms of TARR developing on your lawn, various fungicide applications can be used to treat it.

Cultural Controls

Several cultural controls can help prevent and treat take-all root rot from forming:

  • Water management: Overwatering can promote fungal growth and expansion. Regularly check your irrigation controls to keep from overwatering your lawn.
  • Dethatching: Regular dethatching is essential for proper lawn maintenance and can significantly reduce the risk of TARR. This practice helps remove the buildup of organic matter, allowing for better airflow and moisture penetration into the soil.
  • Lawn aeration: Compacted soil can create an environment conducive to fungal growth by restricting oxygen flow. Aerating the soil helps alleviate compaction and promotes better soil structure, reducing the risk of TARR.
  • Fertilizing: Proper fertilization is crucial for maintaining healthy soil conditions. Avoid overusing nitrogen, as excessive nitrogen can fuel fungal growth. Instead, opt for a balanced fertilizer that provides essential nutrients without promoting fungal growth.

Chemical Controls

Chemical controls offer another avenue for TARR treatment, complementing cultural practices. Fungicides play a crucial role in managing this fungal disease. High-quality fungicides, specifically formulated to target TARR, are recommended.

These fungicides should be applied at regular intervals, typically every 14 days, to affected areas. This consistent application helps combat the spread of the fungus and promotes turf recovery. It’s important to follow the manufacturer’s instructions carefully when applying fungicides to ensure effectiveness and safety.

Additionally, consult with a lawn care professional for guidance on selecting the most appropriate fungicide for your specific situation. Breed notes that despite the prevalence of TARR in Dallas lawns this spring, there are no signs of the disease at properties where preventative fungicide is regularly applied.

Key Takeaways

Take-all root rot (TARR) is a common fungal disease affecting warm-season lawns in Texas, particularly St. Augustine and Bermuda grass.

Environmental Conditions

Specific environmental conditions, including high humidity, mild temperatures, alkaline soils, improper mowing practices, and excessive thatch buildup, promote TARR development. Understanding these conditions can help homeowners take proactive steps to prevent TARR.


Recognizing the signs and symptoms of TARR is crucial for early diagnosis and treatment. Yellow-brown patches on the turf, neon yellow tips on grass blades, greyish-black roots, and thinning grass are indicators of TARR infection.

Treatment and Prevention

Various cultural and chemical controls are available to manage TARR:

  • Cultural controls: Proper water management, dethatching, lawn aeration, and balanced fertilization help prevent TARR formation.
  • Chemical controls: Fungicides play a crucial role in managing TARR. High-quality fungicides, specifically formulated to target TARR, should be applied at regular intervals to affected areas.

Combining these strategies effectively manages TARR and maintains healthy lawns throughout the year.