Take-All Root Rot in Jacksonville Lawns: How to Fight It

If you've noticed sections of your St. Augustine lawn gradually thinning out, yellowing in irregular patches that resist fertilizer and irrigation, you might be dealing with one of Jacksonville's most frustrating fungal diseases. Take-all root rot, caused by the fungus Gaeumannomyces graminis var. graminis, is becoming increasingly common across Northeast Florida, particularly in newer developments where alkaline fill dirt creates the perfect conditions for this devastating pathogen to thrive.

Unlike many lawn diseases that respond well to standard fungicide treatments, take-all root rot requires a completely different management approach focused on altering soil chemistry. At Jax Sod, we've seen this disease destroy otherwise healthy St. Augustine lawns across Nocatee, Ponte Vedra, St. Johns, and newer neighborhoods throughout Duval and St. Johns County. The good news is that with proper diagnosis and a systematic long-term strategy, you can reclaim your lawn from this persistent disease.

Understanding what you're fighting and why it's become such a problem in Jacksonville is the first step toward effective control. Let's dive into what take-all root rot is, how to identify it, and most importantly, how to treat and prevent it in your Northeast Florida lawn.

What Is Take-All Root Rot?

Take-all root rot is a soil-borne fungal disease caused by Gaeumannomyces graminis var. graminis, a pathogen that specifically attacks the root system of turfgrasses. While this fungus can technically affect several grass species, it shows a particular affinity for St. Augustine grass, which happens to be the most popular lawn grass across Jacksonville, Jacksonville Beach, Mandarin, and surrounding areas.

The fungus attacks the root system, causing roots to rot and darken. Infected roots become short, black, and stubby, losing their ability to absorb water and nutrients effectively. What makes take-all root rot especially insidious is that the damage occurs underground, long before you see significant symptoms in the grass blades above. By the time your lawn shows obvious signs of distress, the root system has already been severely compromised.

The disease earned its dramatic name from wheat farmers, where a related strain can completely destroy entire crops. In turfgrass, take-all root rot doesn't typically kill the grass outright in one season, but it progressively weakens the root system over multiple growing seasons. Affected areas become increasingly thin, unable to compete with weeds, and more susceptible to other stresses like drought, cold damage, and secondary diseases.

Why Take-All Root Rot Is Increasing in Jacksonville

If you've lived in Jacksonville for a few decades, you might remember when take-all root rot was relatively rare. That's changed dramatically over the past 15-20 years, particularly in newer residential developments. Several factors have combined to create ideal conditions for this disease across Northeast Florida.

The single biggest contributor is the widespread use of alkaline fill dirt in new construction. As Jacksonville has expanded into areas like Nocatee, Fruit Cove, and developments along the First Coast, builders have brought in fill dirt to level lots and improve drainage. Much of this fill material has a higher pH than Jacksonville's native sandy, slightly acidic soil. While our natural soils typically range from pH 5.5 to 6.5, these construction sites often have soil pH levels of 7.0 or higher.

Gaeumannomyces graminis thrives in alkaline conditions. When soil pH rises above 6.5, the fungus becomes increasingly active and aggressive. At the same time, St. Augustine grass performs best in slightly acidic conditions, so the higher pH stresses the grass while favoring the pathogen. This creates a perfect storm where your lawn is weakened while the disease organism is strengthened.

Other contributing factors include overwatering, poor drainage, excessive thatch accumulation, and improper fertilization practices. Jacksonville's heavy summer rainfall, combined with homeowners following aggressive irrigation schedules, creates persistently moist soil conditions that favor fungal growth. Many well-meaning homeowners also apply quick-release, high-nitrogen fertilizers that promote lush top growth at the expense of root development, making grass more vulnerable to root diseases.

Identifying Take-All Root Rot Symptoms

Early detection is crucial for managing take-all root rot effectively. Unfortunately, the symptoms can initially mimic other common lawn problems, leading many Jacksonville homeowners to misdiagnose the issue and apply inappropriate treatments. Learning to recognize the distinctive signs of this disease will save you time, money, and frustration.

Above-Ground Symptoms

The first signs appear as irregular patches of grass that seem slightly off-color, taking on a yellowish or light green appearance. Unlike the distinct circular patterns you'd see with brown patch or dollar spot, take-all root rot typically creates irregular, elongated patches that may follow contours of the landscape or areas where soil conditions vary.

As the disease progresses, these patches thin out considerably. The grass blades may turn yellow, then tan, but often don't die completely right away. Instead, you'll notice that the turf becomes progressively thinner, with more soil visible between grass plants. Affected areas feel spongy underfoot and lack the dense, resilient quality of healthy St. Augustine.

One telltale sign is that these problem areas don't respond to fertilizer. In fact, applying quick-release nitrogen fertilizer often makes the symptoms worse. Irrigation doesn't help either. Unlike drought stress, which improves quickly when you water, take-all root rot symptoms persist regardless of moisture levels because the damaged roots can't absorb the water anyway.

Below-Ground Symptoms

The diagnostic confirmation comes when you examine the root system. Grab a handful of grass in an affected area and gently pull upward. With take-all root rot, the grass often lifts up easily because the root system is so compromised. Healthy St. Augustine should resist pulling and have extensive white or tan roots extending 4-6 inches into the soil.

Inspect the roots closely. Take-all root rot produces characteristic short, black, stubby roots that look distinctly different from healthy roots. These darkened roots may only extend an inch or two into the soil, compared to the much deeper root system of healthy grass. The roots may also appear rotted, breaking apart easily when you handle them.

Use a knife or trowel to cut and lift a section of affected sod. If the root system is sparse, dark, and shallow, with extensive root death evident, you're looking at classic take-all root rot symptoms.

Conditions That Favor Take-All Root Rot

Understanding what conditions promote this disease helps you make management decisions that tilt the balance back in favor of your lawn. Take-all root rot doesn't appear randomly; it develops when specific environmental and cultural factors align.

High soil pH is the primary driver. As mentioned earlier, pH levels above 6.5 create increasingly favorable conditions for Gaeumannomyces graminis. If you're in a newer Jacksonville neighborhood, particularly in areas like Nocatee, Julington Creek, or developments in Clay County, there's a strong likelihood your soil pH is higher than ideal. Testing your soil pH is an essential first step in diagnosing and treating this disease.

Persistent soil moisture promotes fungal activity. Jacksonville receives approximately 52 inches of annual rainfall, with the heaviest precipitation from June through September. When this natural moisture is supplemented with frequent irrigation, particularly in poorly drained areas, the soil remains wet enough to favor root rot fungi. Following SJRWMD watering restrictions, which limit irrigation to two days per week, can actually help by allowing soil to dry between waterings.

Lawn stress from any source makes grass more vulnerable. Compacted soil, excessive thatch, improper mowing height, and aggressive fertilization with quick-release nitrogen all stress grass and increase susceptibility to take-all root rot. St. Augustine grass that's maintained at 3.5-4 inches with sharp mower blades, fertilized with slow-release products, and not subjected to heavy foot traffic will show much better resistance.

Treatment Strategies for Take-All Root Rot

Successfully managing take-all root rot in Jacksonville lawns requires a comprehensive strategy that addresses soil chemistry, cultural practices, and in some cases, fungicide applications. This isn't a quick fix—expect to invest 1-2 years in systematically improving conditions and rebuilding your lawn's health.

Lowering Soil pH

The foundation of take-all root rot treatment is acidifying your soil to create conditions that favor your grass over the fungus. Begin by testing your soil pH at a UF/IFAS Extension office or using a reliable home test kit. If your pH is 6.5 or higher, you need to lower it to the 5.5-6.2 range where St. Augustine thrives and Gaeumannomyces graminis is suppressed.

Acidifying fertilizers are your primary tool. Products containing ammonium sulfate or sulfur-coated urea gradually lower soil pH over time while providing nutrients. Look for fertilizers specifically labeled for acid-loving plants or those designed for use in high-pH soils. Apply these according to label directions, typically 3-4 times per year during the growing season.

Elemental sulfur is another option for more aggressive pH reduction. Apply 5-10 pounds of elemental sulfur per 1,000 square feet, working it into the top inch of soil if possible. Be patient—sulfur takes 2-3 months to significantly affect soil pH. Test regularly and adjust application rates based on results. Jacksonville's sandy soils allow sulfur to work relatively quickly compared to clay soils, but you still need multiple applications over 1-2 years to reach and maintain your target pH.

Peat moss topdressing provides both acidification and physical benefits. Apply a quarter-inch layer of peat moss over affected areas, then lightly rake it into the turf. The peat moss gradually lowers pH while improving soil structure and encouraging new root growth. For severely affected areas, consider applying peat moss topdressing every 4-6 weeks during the growing season.

Fungicide Applications

While correcting soil pH is the long-term solution, fungicides can help suppress take-all root rot in the short term, particularly during the establishment phase of your treatment program. The most effective active ingredient is fenarimol, a systemic fungicide that's absorbed by roots and moved throughout the plant.

Fenarimol-based products must be watered in immediately after application to move the active ingredient into the root zone where the fungus resides. Apply according to label directions, typically every 30 days during active growing season. Be aware that fenarimol is a preventive and suppressive fungicide—it won't cure advanced infections, but it can slow disease progression while you work on correcting underlying soil conditions.

Other fungicides labeled for take-all root rot include propiconazole and azoxystrobin. These are most effective when combined with cultural practices that reduce soil pH and improve overall turf health. Fungicide applications alone, without addressing soil chemistry, provide only temporary relief.

Jacksonville Pro Tip: Apply fungicides in early spring, just as St. Augustine begins active growth, and continue monthly applications through October for best disease suppression during the growing season.

Cultural Practices

Adjusting your maintenance practices is crucial for managing take-all root rot successfully. Start by raising your mowing height to 3.5-4 inches. Taller grass produces deeper roots and more carbohydrates through photosynthesis, helping the plant overcome root damage. Keep mower blades sharp to avoid tearing grass blades, which creates additional stress.

Reduce irrigation frequency while increasing duration. Instead of watering 3-4 times per week, follow SJRWMD restrictions and water only on your designated days (odd addresses Wednesday and Saturday, even addresses Thursday and Sunday). When you do water, apply 0.5-0.75 inches to encourage deep rooting rather than shallow, frequent watering that keeps surface soil constantly moist.

Switch to slow-release fertilizers with controlled-release nitrogen. Quick-release nitrogen promotes excessive top growth at the expense of root development, exactly the opposite of what you need when fighting root disease. Look for products with at least 50 percent slow-release nitrogen. Reduce total nitrogen applications to 2-3 pounds per 1,000 square feet annually, split across 3-4 applications.

Core aeration in spring and fall improves soil drainage, reduces compaction, and allows acidifying amendments to penetrate more effectively. For Jacksonville's sandy soils, aeration isn't always necessary, but if you have heavy traffic areas or imported fill dirt with higher clay content, aeration helps significantly.

Rebuilding Affected Areas

Severely damaged areas may need complete renovation once you've corrected the underlying soil conditions. If pH testing confirms you've achieved the 5.5-6.2 target range and maintained it for at least 6 months, but certain areas remain thin and unproductive, it's time to consider replacement.

For small patches (less than 20-30 square feet), you can cut out damaged sod and replace it with fresh, healthy St. Augustine. Remove 4-6 inches of soil depth, backfill with new soil amended with peat moss to ensure slightly acidic conditions, and install fresh sod. Water daily for 2-3 weeks until roots establish, then transition to normal irrigation schedule.

Larger areas may require more extensive renovation. If take-all root rot has affected 30 percent or more of your lawn, consider a complete lawn replacement after correcting soil pH. This allows you to start fresh with healthy sod installed in improved soil conditions. At Jax Sod, we've helped dozens of Jacksonville homeowners through this process, and when done correctly with proper pH management, the results are dramatic and long-lasting.

Choose disease-resistant varieties when replanting. While no St. Augustine variety is completely immune to take-all root rot, Palmetto and CitraBlue show better tolerance than older varieties like Floratam. If your property is suitable for alternative grasses, Bermuda varieties like TifTuf or Celebration, or Zoysia varieties like Empire show excellent resistance to take-all root rot.

Long-Term Management and Prevention

Once you've gotten take-all root rot under control, maintaining control requires ongoing attention to soil pH and cultural practices. Think of this as a long-term management strategy rather than a one-time fix.

Test soil pH annually, preferably in early spring before the growing season begins. Jacksonville's irrigation water quality, rainfall, and fertilizer applications all affect pH over time. If you see pH creeping back above 6.5, resume acidifying treatments before disease symptoms reappear.

Continue using acidifying fertilizers even after symptoms resolve. Switching back to non-acidifying products allows pH to drift upward again, recreating conditions that favor the disease. Many Jacksonville homeowners successfully maintain healthy St. Augustine lawns by consistently using ammonium sulfate-based fertilizers as their primary nitrogen source.

Monitor your lawn regularly for early warning signs. If you notice areas beginning to thin or lose color despite adequate irrigation and fertilization, check the roots. Catching take-all root rot early, when root damage is still minimal, makes treatment much more effective than waiting until large areas are severely affected.

Document your treatment program, including application dates, products used, and soil test results. This record helps you see what's working and makes it easier to maintain a consistent program. It's also valuable information if you work with a professional lawn care company or need to explain the situation to a future property owner.

Common Mistakes to Avoid

Having worked with Jacksonville homeowners dealing with take-all root rot for over 37 years, we've seen several common mistakes that delay recovery or make the problem worse.

The biggest error is misdiagnosing the problem and treating it as a nutrient deficiency. When homeowners see yellowing, thinning grass, the instinctive response is to apply more fertilizer, particularly high-nitrogen formulas. With take-all root rot, this makes the problem worse by promoting top growth that the compromised root system can't support.

Overwatering is another frequent mistake. The logic seems sound—if the grass looks stressed, give it more water. But since the roots are damaged and unable to absorb water efficiently, increasing irrigation just creates more favorable conditions for the fungus while doing nothing to help the grass.

Expecting overnight results leads to abandoning treatment too soon. Lowering soil pH and rebuilding root systems takes time. Many homeowners apply acidifying products for 2-3 months, don't see dramatic improvement, and give up. Stick with the program for at least one full growing season before evaluating effectiveness.

Using home remedies or non-specific fungicides wastes money and delays effective treatment. Take-all root rot requires specific management targeting soil pH and the fungal pathogen. Generic fungicides or folk remedies don't address the underlying soil chemistry issues that allow the disease to thrive.

When to Seek Professional Help

While many Jacksonville homeowners successfully manage take-all root rot with the strategies outlined here, some situations benefit from professional expertise. If you've been battling this disease for more than one growing season without improvement, it's time to call in professionals who can assess your specific situation and adjust the treatment program.

Professional lawn care companies have access to commercial-grade fungicides and acidifying products that may be more effective than homeowner-available options. They can also conduct detailed soil testing beyond basic pH to identify other factors that might be contributing to disease severity.

If you're dealing with widespread damage affecting more than 30-40 percent of your lawn, professional consultation can help you decide whether to continue treating or whether complete renovation is the more cost-effective option. At Jax Sod, we provide comprehensive assessments that factor in soil conditions, grass variety, maintenance history, and your budget to develop realistic treatment plans.

For new construction in neighborhoods like Nocatee, Bartram Park, or developments in St. Johns County where alkaline fill dirt is common, working with professionals from the start can prevent take-all root rot from gaining a foothold. Soil amendment before sodding, choosing appropriate grass varieties, and establishing proper pH maintenance from day one is much easier than fighting established disease.

Ready to Win the Battle Against Take-All Root Rot?

Take-all root rot is one of Jacksonville's most challenging lawn diseases, but it's not unbeatable. With proper diagnosis, systematic pH management, appropriate fungicide use, and improved cultural practices, you can restore your St. Augustine lawn to health and keep this disease under control long-term. The key is understanding that you're managing soil chemistry as much as you're treating a disease, and success requires patience and consistency.

Whether you're dealing with early symptoms in small patches or facing widespread damage across your Ponte Vedra, Mandarin, or Southside lawn, starting with soil testing and acidification puts you on the right path. Remember that this is a marathon, not a sprint—most successful recovery programs take 1-2 years to fully restore lawn health.

Ready to tackle take-all root rot in your Jacksonville lawn? Contact Jax Sod today at (904) 901-1457 or visit jaxsod.com for a free estimate. Our team brings 37+ years of experience helping Northeast Florida homeowners diagnose and treat complex lawn problems, and we're here to help you restore your lawn to the thick, healthy turf you deserve.