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Hosts Annual bluegrass, creeping bentgrass, and rough bluegrass. The pathogen does not appear to affect perennial ryegrass, fescues, or Kentucky bluegrass.
Cause A fungus, Waitea circinata (asexual Rhizoctonia sp.), that lives in soil and on diseased vegetation of nearly any kind. First confirmed as a disease in western Washington in 2003 and then characterized from annual bluegrass putting greens in California, Nevada, and Washington. The fungus colonizes the foliage, crowns, upper roots, and thatch in affected areas. Cultural conditions associated with brown ring patch include low nitrogen fertility and thatch accumulation. Extent of the problem in the Pacific Northwest is unknown.
Symptoms Thin yellow rings or semicircles, several centimeters to one meter in diameter, that can turn brown or necrotic and often have a sunken appearance. Turfgrass is slow to recover. Symptoms are typically observed at a range of 60°F to 95°F maximum daytime air temperature.
Cultural control
- Maintain an adequate, balanced nutritional program.
- Remove thatch and aerify compacted areas.
- Mow higher in periods of stress such as dry or hot weather.
Chemical control Focus on cultural control tactics. Control is difficult as multiple fungicide applications are often needed to eradicate the pathogen from the crowns, upper roots, and thatch for complete control. Tolerant strains of many fungal pathogens can become troublesome when some fungicides are used exclusively in a spray schedule. To prevent developing resistant fungi, alternate or tank-mix materials from different groups with different modes of action. Limit the use of any one group during crop production.
Products available in home packaging:
- Infuse Systemic Disease Control at 5 fl oz/1 gal water/250 sq ft of lawn. Group 3 fungicide. H
- Spectracide Immunox Multi-Purpose Fungicide Spray Concentrate for Gardens at 7 fl oz/gal water over 500 sq ft. Group 3 fungicide. H
Products available for commercial use:
- Affirm WDG at 2.4 lb/A. Do not irrigate for 12 hours after application. Group 19 fungicide. 4-hr reentry.
- Densicor at 8.5 fl oz/A or 0.196 fl oz/1,000 sq ft. Do not use hand held equipment. Group 3 fungicide. Reenter when sprays have dried.
- Disarm 480 SC at 0.18 to 0.36 fl oz/1,000 sq ft. Group 11 fungicide. 12-hr reentry.
- Endorse WP at 11 lb/A. Group 19 fungicide. 4-hr reentry.
- Fame SC at 0.2 to 0.4 fl oz/1,000 sq ft. Group 11 fungicide. 12-hr reentry.
- Insignia SC at 0.7 fl oz/1,000 sq ft. Do not use with organosilicate adjuvants. Group 11 fungicide. 12-hr reentry.
- Maxtima at 0.6 fl oz/1,000 sq ft followed by 0.25 in irrigation. Group 3 fungicide. 12-hr reentry.
- Medallion SC at 1 to 2 fl oz/1,000 sq ft. Apply after mowing. Use with oils or adjuvants may cause plant damage. Group 12 fungicide. 12-hr reentry.
- Mirage at 1 to 2 fl oz/1,000 sq ft. Group 3 fungicide. 12-hr reentry.
- Monsoon Turf at 0.6 fl oz/1,000 sq ft. Group 3 fungicide. 12-hr reentry.
- ProStar 70 WG at 2.2 to 4.5 oz/1,000 sq ft. Water in applications lightly. Group 7 fungicide. 12-hr reentry.
- Tebuzol 3.6F at 0.6 fl oz/1,000 sq ft. Group 3 fungicide. No reentry interval listed.
- Torque at 0.6 to 1.1 fl oz/1,000 sq ft. Do not mix with growth regulators during hot weather as injury may develop. Group 3 fungicide. 12-hr reentry.
- Tourney EZ at 0.37 oz/1,000 sq ft. Do not apply to Poa annua putting greens. Group 3 fungicide. 12-hr reentry.
- Trinity at 1 to 2 fl oz/1,000 sq ft. Do not mix with growth regulators during hot weather as injury may develop. Group 3 fungicide. 12-hr reentry.
- Turfcide 400 at 5 to 6 fl oz/1,000 sq ft. Irrigate with 0.25 inch water immediately after application. Do not use hand application equipment or mow for 1 day after application. Under certain growing conditions a temporary discoloration of the grass may occur. Group 14 fungicide. 12-hr reentry.
- Velista at 0.5 oz/1,000 sq ft. Group 7 fungicide. 12-hr reentry.
Combination Fungicides
- Briskway at 0.5 to 1.2 fl oz/1,000 sq ft. Can be used in hot weather. Group 3 + 11 fungicide. Reentry when sprays have dried.
- Concert at 3 to 5.5 fl oz/1,000 sq ft. Do not use on fine fescue turf. Group 3 + M5 fungicide. 12-hr reentry.
- Heritage Action at 0.2 to 0.4 oz/1,000 sq ft. Group 11 + P1 fungicide. 12-hr reentry.
- Lexicon at 0.34 to 0.47 fl oz/1,000 sq ft. Group 7 + 11 fungicide. 12-hr reentry.
- Navicon at 0.7 fl oz/1,000 sq ft followed by 0.25 in irrigation. Group 3 + 11 fungicide. 12-hr reentry.
- Pillar G at 3 lb/1,000 sq ft. Group 3 + 11 fungicide. 12-hr reentry.
- Premion at 6 to 8 fl oz/1,000 sq ft. Group 3 +14 fungicide. Reentry when sprays have dried.
Reference Chen, C., de la Cerda, K.A., Kaminski, J.E., Douhan, G.W., and Wong, F.P. 2009. Geographic distribution and rDNA-ITS region sequence diversity of Waitea circinata var. circinata isolated from annual bluegrass in the United States. Plant Disease 93:906-911.