Brown Patch is a Cool Weather Disease in St Augustine Lawns


By Rick Orr 01/04/2021


Brown Patch damaged St Augustine Lawn
A St Augustine lawn with a severe case of brown patch, Circular patterns of damage are a signature of brown patch.

Brown Patch

Those brown circular patches in your St Augustine turfgrass lawn are probably brown patch. Brown Patch forms distinct circles or joined lobed circles of dead leaves with a “halo” of yellow grass. It does not kill the turfgrass, it only affects the leaves. The results are a patchwork of crop circles.

What to expect from Brown Patch

Brown Patch is a cold season disease of fall and spring. Brown Patch forms circles and/or lobed circles of tan/green weak turf that is flattened – like a round weight had been placed on the turf. The rings start out fist size and can grow to be 20 feet in diameter or larger. The outer edge of the ring (active area) is a multi-colored, mainly yellow in color, and is very distinct. Brown Patch responds to fertilizer - especially readily available nitrogen – by getting worse and to potassium by declining.

Also, expect St Augustine to fully recover when cultural conditions change – i.e. the weather warms or cools.

Cause and Cure

The fungus that causes brown patch is natural part of the turf ecosystem recycling matter and cannot be eradicated. During the cooler weather of fall and spring, the fungi will attack living tissue - usually just the leaves.  The Good News: Except for the worse cases, Brown Patch can be controlled with good cultural practices!

Cold vs. Deadly Disease

My experience with Brown Patch has me categorizing it as a “cold” as opposed to a “deadly disease”. I think the “cold analogy” is a good one because:

  • Brown Patch generally will not kill your grass – unless it is near death, to begin with.

  • It is a temporary condition – Brown Patch thrives at moderate soil temperatures and as the soil temperature rises (or lowers), Brown Patch will cease to be a problem.

  • Many lawns are not effected by Brown Patch, and others have chronic problems with Brown Patch (not everyone catches a cold).

The causal agent is part of the environment – it is a soil born disease and cannot be eliminated. Since it is not life-threatening, I manage the Brown Patch with biological methods to reduce occurrences and treating only severe occurrences with commercially manufactured fungicides.


Since the disease responds to fertilizers and is not lethal, manipulating fertilizers is the best management practice for controlling Brown Patch. To reduce the impact of Brown Patch during the cool season months, APL Pest Control uses slow release organic sources for nitrogen in very sparse amounts and high amounts of potassium to keep nitrogen levels low and potassium levels high, This is safer then applying chemical fungicides.  However, in severe cases, I will use a commercially available fungicide as a curative measure. In the 700 or so lawns I service, I only have about 5 that are problematic for Brown Patch and require fungicides; therefore the manipulating of the fertilizer elements is a good management practice for controlling Brown Patch.

Rick Orr Owner-Operator APL Pest Control/Creator of ILOVETURF.COM
APL Pest Control

Rick Orr is the creator of, Owner/Operator of APL Pest Control, and a graduate of VA Tech in Agronomy (Turf Ecology).  

Since 1980, Rick worked in the green industry, mostly with golf courses, resorts, and large communities. Rick worked as a Golf Course Superintendent of Fripp Island Resort, agronomist for Seaside, FL, and the spray tech for Vinoy Golf Course. Rick has been certified as an arborist, landscape and irrigation contractor, and adjunct professor for Environmental Horticulture (SPC) in Pinellas County.  

Home Pest Control came naturally. Entomology (bug science) was part of agronomy studies. Nearly every indoor pest problem starts outdoors. Crossing over to home pest control from lawn spraying was a natural process – the technology, methods, and materials used for home pest control are modifications of the ones used for lawn spraying. 

The result of that work is one of the top-rated pest control companies in Pinellas County – APL Pest Control. APL Pest Control is a family-owned business serving residential and commercial properties in Pinellas County, FL. 

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Speaking Engagements - Does it seem like you are only hearing one side of water restrictions, fertilizer bans, plant restrictions, and many other urban landscape hot topics? Rick Orr is available for speaking engagements for your HOA, Community or Professional Association, or Garden Club about a variety of subjects. To contact Rick you can find him on FacebookTwitterLinkedIn, and Instagram for booking information.