Nebraska Cooperative Extension G84-688-A (Revised June 1999)

A University of Nebraska NebGuide Publication

Brown Patch Disease of Turfgrass

This NebGuide describes the symptoms and disease cycle of brown patch and gives recommendations for its prevention and control through management, including use of fungicides.

John E. Watkins, Extension Plant Pathologist
Robert C. Shearman, Extension Turfgrass Specialist

Brown patch of turfgrass is caused by the fungus Rhizoctonia solani Kuehn. All commonly cultivated turfgrasses in Nebraska are affected by this disease, but differences in susceptibility exist within cultivars of the various turfgrass species. Primary hosts are bentgrass, perennial ryegrass, tall fescue and annual bluegrass. Certain species of Rhizoctonia are capable of attacking turfgrass plants from seedling stage to mature plants and are pathogenic over a wide range of environmental conditions. In some literature, brown patch may be referred to as Rhizoctonia blight. In zoysiagrass, it is referred to as large brown patch. 


Figure 1. Roughly circular patches typical of brown patch on taller-cut turfgrass.
Figure 2. Irregularly-shaped leaf spot of brown patch (right) and bleached leaf spot of dollar spot.
Figure 3. Brown patch symptoms on a bentgrass green.
Figure 4. Spread of brown patch by mowing.
Brown patch symptoms vary, depending primarily on turfgrass species and mowing height. The degree of turfgrass injury depends largely on susceptibility of the cultivar, management practices and weather conditions.

On home lawns, golf course fairways and similar turfs, field expression of the disease is the presence of roughly circular patches of dead and dying grass (Figure 1). Diseased areas may encompass large portions of the turf. Turf with these patches appears somewhat "sunken." The grass in the center of the diseased patches may be less affected, giving the appearance of the "frog-eye" symptom commonly associated with summer patch. However, the presence of the characteristic brown patch leaf spot on individual blades should distinguish it from this disease. Also, the affected turf appears less matted than that affected by summer patch.

Green plants within the affected turf have grayish-colored leaf spots that are long, irregularly shaped and surrounded by a dark brown margin (Figure 2). Diagnosis of brown patch should be made not only on the characteristic leaf spot symptom, but also should include gross symptomatology of the affected turf, and, in some situations, culturing of the pathogen.

On bentgrass greens, symptoms appear as roughly circular, reddish-brown patches that vary in size from 6 to 8 inches to a foot or more in diameter (Figure 3). Infected grass blades first appear water-soaked and purplish-green. They soon die and turn light brown. Occasionally, a grayish "smoke ring" 1 to 2 inches wide and composed of wilting, webbed grass blades marks the advancing margin of the patch. The smoke ring is best observed in early morning while dew is present.

Disease Cycle

Rhizoctonia solani survives from year to year in the form of mycelium or bulbils (resting bodies of the fungus) in plant debris and thatch. As such, it also is capable of existing away from the host as a saprophyte. As average daily temperatures reach the mid-70s, the bulbil germinates and forms fungal hyphae, which spread through the soil surface and thatch. During humid, hot weather, the hyphae grow onto moist grass blades and enter the plant through wounds and stomates (natural leaf pores). Local spread is by mycelium bridging from plant to plant. Longer distance spread is by mycelium clinging to wet mower wheels during early morning mowing. This sometimes causes symptoms to appear in a wheel track pattern (Figure 4), rather than in the characteristic circular pattern.

Factors Favoring Brown Patch

Brown patch occurs on dense, heavily fertilized and watered turf in hot (above 85°F), humid weather when night temperatures remain above 60°F. Poorly drained soils, thick thatch and night irrigation lengthen the period of leaf wetness and promote greater infection. High levels of nitrogen and low levels of phosphorous or potassium may contribute to increased disease severity. Mowing with a dull mower blade frays leaf blade tips and causes excessive wounding that enhances infection through those frayed blade tips.

Integrated Disease Management

Table I. Fungicides for the management of Rhizoctonia brown patch.*

Common Name Some Trade Names Professional (P)/
Homeowner (H) Use

Azoxystrobin Heritage (Zeneca) P
Benomyl Benomyl (Hi Yield) H
Benomyl Lawn Fungicide (Bonide) H
Benomyl Systemic Fungicide (American) H
Benomyl Spray (Security) H
Chloroneb Chloroneb (Andersons) P
Fungicide V (Scotts) P
Teremec SP (PBI/Gordon) P
Terraneb SP (Kincaid) P
Chlorothalonil** Daconil 2787 (Zeneca) P
Daconil 2787 Weather Stik (Zeneca) P
Daconil Ultrex (Zeneca) P
Manicure (LESCO) P
Thalonil (Terra) P
Turf Fungicide (Lebanon) P
Chlorostar (Regal) P
Cyproconazole Sentinel (Novartis) P
Fenarimol Rubigan A.S. (Dow AgroSciences) P
Patchwork (Riverdale) P
Flutolanil ProStar (AgrEvo) P
Iprodione Chipco 26019 (Rhone-Poulenc) P
Chipco 26GT (Rhone-Poulenc) P
Fungicide X (Scotts) P
Maneb Pentathlon (Griffin) P
Mancozeb Fore (Rohm and Haas) P/H
Dithane (Rohm and Haas) P
Mancozeb (LESCO) P
Protect T/O (Cleary) P
Junction (Griffin) P
Mancozeb Flowable (Bonide) H
Maneb Plus (Green Light) H
Fore Lawn & Ornamental Fungicide Spray (Acme) H
Myclobutanil Eagle WSP (Rohm and Haas) P
Golden Eagle (Scotts) P
PCNB Defend 2F (Cleary) P
PCNB 75WP (Cleary) P
Engage (United Horticultural Supply) P
Penstar 15G, FLO (Scotts) P
Revere (LESCO) P
Terraclor, Turfcide, Turfcide 400 (Uniroyal) P
Propiconazole Banner MAXX (Novartis) P
Banner GL (Novartis) P
Spectracide Immunex Fungicide Concentrate (Spectrum) H
Quartenary Ammonium Compounds Physan 20 (Maril) P
Thiophanate-methyl 3336 (Cleary)
Cavalier 2G, 50WSB, 4.5 F (LESCO) P
Fungo Flo, 50WSB Systemic Fungicide (Scotts) P
SysTec 1998 (Regal) P
Halt Systemic (Ferti-lome) H
Lawn Fungus Control (Scotts) H
Systemic Fungicide 3336 (Dragon) H
Bonomyl System Fungicide (Bonide) H
Thiram Spotrete 75WDG, F (Cleary) P
Lawn Disease Control (Bonide) H
Defiant (UCB) P
Triadimefon Bayleton (Bayer, Anderson, Lebanon) P/H
Granular Turf Fungicide (LESCO) P
Fungicide VII (Scotts) P
1% Turf Fungicide with Bayleton (Rockland, Bonide) P/H
Accost (United Horticultural Supply) P
Bayleton Systemic Fungicide (LESCO) P
Fungi-Fighter (Monterey) P
Fungisol (Opti-Gro) P
Lawn Fungicide, Bayleton 1G (Howard Johnson's) H
Fung-Away (Green Light) H
Vinclozolin Curalan (BASF) P
Touch, (LESCO) P
Vorlan DF (Scotts) P
Chloroneb+thiophanate-methyl Fungicide IX (Scotts) P
Chloroneb+fenarimol TwoSome Flowable Fungicide (LESCO) P
Chlorothalonil+thiophanate-methyl ConSyst (Regal) P
Spectro 90WDG (Cleary) P
Propamocarb+chlorothalonil LescoPar (LESCO) P
Thiophanate-methyl+iprodione Fluid Fungicide (Scotts) P
Turf Builders plus Fungicide H
Thiophane-methyl+mancozeb Duosan WP, WSB (Scotts) P
Thiram+triadimefon Fluid Fungicide III (Scotts) P
Triadimefon+metalaxyl Fluid Fungicide II (Scotts) P

*Fungicides listed in Table I represent the best information available. No criticism is intended of products not listed, nor is endorsement by the University of Nebraska given to those listed. Read and follow all product label directions.
**Cannot be used on home lawns.

File G688 under PLANT DISEASES

F-5, Turf, 5,000 printed
Revised June 1999

Electronic version issued August 1999

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Elbert C. Dickey, Director of Cooperative Extension, University of Nebraska, Institute of Agriculture and Natural Resources.

University of Nebraska Cooperative Extension educational programs abide with the non-discrimination policies of the University of Nebraska-Lincoln and the United States Department of Agriculture.