Brown Patch: When Turf has a Winter Cold

PINELLAS COUNTY, FLORIDA

By Rick Orr 01/04/2021
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Active brown patch in St Augustine lawn
Active brown patch in a St Augustine lawn. THe "Yellow Halo" around the perimeter is the active area and indicates the fungus is still active.

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:

  1. Brown Patch generally will not kill your grass – unless it is near death, to begin with.
  2. It is a temporary condition – Brown Patch thrives at moderate soil temperatures and as the soil temperature rises (or lowers) the soil Brown Patch will cease to be a problem.
  3. 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 organic methods to reduce occurrences and treating only severe occurrences with conventional fungicides.

What to expect from Brown Patch

Brown Patch is a cool-season disease occurring on cool 70° nights. Brown patch is inactive at temperatures above 75° or below 65°. 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 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.

Treatment with Fungicides

There is no permanent cure. Curative treatments of fungicide will last about 14 days. To prevent brown patch you must treat the turf with a fungicide every14 days before the symptoms occur. Brown patch is most active from October through February. Prevention requires applying the fungicide every 14 days during brown patch season which is cost-prohibitive for most homeowners.

Organic Control of Brown Patch 

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 I use slow, organic sources for nitrogen in very sparse amounts and high amounts of potassium. Manipulating fertilizer is "organic"  – and organic methods are very "green" in practice but slow to develop and weak in performance. Therefore in severe cases, I will use a commercially available fungicide as a curative measure and then return to the organic methods. In the 700+ or so lawns I service, I only have about 5 that are problematic for Brown Patch and require fungicides, for the remaining lawns, manipulating the fertilizer elements work well for controlling Brown Patch.

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

Since 1995, Rick Orr has worked in Pinellas County providing turf management and pest control. Rick Orr is a graduate of VA Tech in Agronomy (Turf Ecology) and the creator of Iloveturf.com.

Since graduating from VA Tech in 1979, Rick worked in the green industry, mostly with golf courses, resorts, and large communities. Rick has obtained certifications in arboriculture, landscape contractor, and irrigation contractor, and taught Environmental Horticulture at St Petersburg College. 

Currently, Rick is the owner and operator of APL Pest Control. APL Pest Control provides lawn care and pest control for all of Pinellas County.

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