Short Answer: Take-all root rot is a soil-borne fungal disease (Gaeumannomyces graminis) that attacks the root system of St. Augustine lawns and shows up as irregular yellow or thinning patches that most homeowners mistake for drought stress. The early sign in North San Antonio is yellow blades along the edges of an irregular patch, easy stolons that pull up with no resistance because the roots are short and rotten, and slow or no recovery after watering. Treatment requires more than fungicide. You need to lower the soil pH at the root zone with elemental sulfur or peat moss top-dressing, switch to deeper less frequent watering, reduce nitrogen, and apply a labeled fungicide (azoxystrobin or propiconazole) at the right depth. Caught early, most lawns recover. Caught late, you are looking at sod replacement.
If you have a North San Antonio St. Augustine lawn that started June looking thin in patches along the front sidewalk, and watering on your SAWS day is not bringing those patches back, you are not just looking at drought stress. We see this every June across Stone Oak, Shavano Park, Hollywood Park, and the Hill Country Village corridor. The homeowner watches the same spots get worse week after week, increases the watering, and the spots keep growing. By August they are calling us with half the yard yellow and brown, asking if they need new sod.
What they actually have, almost every time, is take-all root rot. It is the disease that pretends to be a watering problem. And it is one of the few St. Augustine diseases where the timing of your response matters more than the product. Here is what to look for, why North San Antonio caliche makes it worse, and what we do about it.
What Take-All Root Rot Actually Is
Take-all root rot is caused by Gaeumannomyces graminis var. graminis, a soil-borne fungus that lives in the thatch and upper soil layer and attacks St. Augustine roots and stolons. It thrives in warm, moist soil with a high pH. North San Antonio’s caliche-influenced soils sit at pH 7.5 to 8.2, which is exactly the range the fungus prefers. We are basically a take-all root rot incubator if conditions go wrong.
The fungus does not kill the lawn the way a lot of homeowners assume. It does not eat the blades. It attacks the roots. By the time you see blade yellowing or thinning above ground, the root system below has already lost 40 to 70 percent of its mass. That is why the disease moves slowly for weeks, then seems to explode in a single hot stretch when the roots can no longer pull water out of the soil fast enough to keep up.
What It Looks Like Versus Drought
This is where most North San Antonio homeowners get fooled. Take-all and drought stress look similar from the porch. Here is how to tell them apart in 60 seconds:
- Patch shape: Take-all makes irregular blobs and ribbons that follow the contour of your watering pattern (because the fungus moves with the water). Drought stress hits high spots and edges near hard surfaces first.
- Color progression: Take-all yellows the blades from the base up, often with bright yellow at the leaf base and green at the tip. Drought stress curls and grays the blade from the tip down.
- Stolon pull test: This is the easy one. Reach into a thinning patch and tug on a runner. A healthy St. Augustine stolon resists you. A drought-stressed stolon resists too, just less. A take-all stolon comes up like a piece of string, with short black or brown roots that snap off cleanly.
- Watering response: Drought patches green back within 4 to 7 days of a deep watering. Take-all patches do not improve no matter what you do. Some get worse with more water.
Do the stolon pull test on three suspect spots before you do anything else. If two of three pull up with rotted short roots, you have take-all, not drought.
Why North San Antonio Is a Hotspot
Three things make our zone especially friendly to take-all. First, the alkaline soil. The fungus loves a pH above 7.0, and most of our caliche-influenced soils run higher than that naturally. Second, the warm winters. Many years the soil never drops below 50 degrees, which means the fungus stays alive in the thatch year-round instead of dying back over winter like it does in cool-season regions. Third, the late spring rain pattern. May tends to dump 4 to 6 inches in a few days, then turns dry, which is the exact moisture pulse that wakes the fungus up just as soil temperatures cross 70 degrees.
The neighborhoods we see this in most are the ones with established St. Augustine lawns 15 years or older, where the thatch has built up and the soil has had years to settle into its native pH. Newer construction lawns on imported topsoil are usually safer in year one and two. They start showing the disease around year four or five as the thatch and pH come back to baseline.
The Treatment That Actually Works
A lot of homeowners reach for a single fungicide application and expect the patches to fill in. That almost never works because the fungus is in the root zone, not on the blades, and a sprayer cannot push the active ingredient deep enough. The protocol we use combines four pieces, and skipping any of them slows recovery to a crawl.
Step 1, lower the soil pH at the root zone. This is the most important and most overlooked step. Top-dress the affected areas with peat moss at a rate of one bale per 50 square feet, raked in lightly. Or apply elemental sulfur at 5 pounds per 1,000 square feet (split into two applications a month apart). The goal is to bring the soil pH in the top 3 inches down to around 6.5, which the fungus does not like. This change alone slows the disease meaningfully even before you apply any fungicide.
Step 2, change the watering. Take-all loves frequent shallow water. Switch to deep, infrequent watering aligned with your SAWS day. One soak that gets water 4 to 6 inches deep, no light interim waterings, no evening cycles. This works against the fungus’s preferred moisture pattern.
Step 3, drop the nitrogen. High nitrogen pushes top growth that the damaged root system cannot support. Stop applying nitrogen on affected lawns through June and July. Resume a modest fall application only after recovery is clear.
Step 4, apply a labeled fungicide at the right depth. Azoxystrobin (Heritage) or propiconazole (Banner Maxx) are the two active ingredients with the best track record on take-all in St. Augustine. The application matters. Spray at high water volume (at least 5 gallons per 1,000 square feet), then water it in lightly so the product moves into the root zone. A surface-only spray will not reach the fungus.
How Long Recovery Takes
Be realistic. A take-all lawn caught in early June, treated correctly, usually shows new stolon growth into the patches by late July and substantial fill-in by September. Full visual recovery often takes into October or even the following spring on heavily affected lawns. The pace depends on how much root mass was lost before treatment.
If half the lawn is already brown and the stolons come up in long ribbons everywhere you test, sod replacement is on the table. We are honest with customers about this. Throwing fungicide at a lawn that has already lost 80 percent of its root mass is wasted money. We will tell you when treatment makes sense and when patching with new sod is the better call.
What You Can Do This Week
Walk the lawn this weekend. Do the stolon pull test on three suspect spots. If even one comes up easy with rotted roots, get a soil pH test (Lowe’s and most garden centers sell a $15 probe kit, or your county extension will test for free). If the pH is above 7.0 and you have thinning patches, you are almost certainly dealing with take-all and the clock matters.
Skip the temptation to drown the lawn. More water makes take-all worse, not better. Skip the urge to fertilize the brown spots green. Nitrogen makes take-all worse. The right moves are pH correction, controlled watering, and the right fungicide at the right depth.
What to Do Next
If your North San Antonio lawn has yellow or thinning patches that are not responding to watering, we would rather you call us in early June than in mid-August. The disease is treatable when it is identified early, and the protocol is specific enough that getting it wrong wastes a season.
Lawn Squad of North San Antonio serves homeowners across the North San Antonio area, including the Stone Oak, Hollywood Park, Shavano Park, Castle Hills, and Hill Country Village neighborhoods.
Call us at 210-588-0275 or request a free quote at lawnsquad.com. Our VitaminLawn program is built specifically for North San Antonio’s St. Augustine, Bermuda, and Zoysia lawns growing on alkaline caliche, and our disease protocols are tuned to the pathogens that actually hit this region. We will diagnose the issue on-site, not over the phone, and give you a straight answer on whether treatment or sod replacement is the smart play.
