Host Bluegrass, bentgrass, and annual bluegrass have shown infections.
Cause The fungus Ceratobasidium cereale (formerly Rhizoctonia cerealis). The disease also is often referred to as cool-season Rhizoctonia. Because it is active at relatively cool temperatures, it is likely to be more common in the Pacific Northwest than brown patch (R. solani). Prolonged periods of leaf wetness, poor drainage, thatch accumulation, cloudy weather, and over-fertilization favor disease development.
Symptoms Symptoms first appear in fall and can be seen throughout a mild winter and in spring if weather conditions are favorable (prolonged moisture at 40°F to 60°F). Light brown to yellow patches and rings form on affected turf. Patches usually recur in the same locations.
Microscopic examination reveals abundant R. cerealis hyphae on affected sheaves and leaves. Generally, under good management turf will recover rather quickly when weather becomes unfavorable (too dry, warm, or cool) for disease.
Cultural control
- Provide good management to ensure deep rooting.
- Maintain moderate N-P-K rates with consistent applications all year.
- Avoid excessive irrigation.
- Sweep greens to encourage drying.
- Reduce thatch by mechanical means.
Chemical control Fungicides effective against R. solani (brown patch) are not consistently effective against yellow patch.
- Disarm 480 SC at 0.36 fl oz/1,000 sq ft. Group 11 fungicide. 12-hr reentry.
- Fame SC at 0.2 to 0.4 fl oz/1,000 sq ft. Group 11 fungicide. 12-hr reentry.
- Heritage at 0.2 to 0.4 oz/1,000 sq ft. Group 11 fungicide. 4-hr reentry.
- Medallion SC at 2 fl oz/1,000 sq ft. Tank-mix with another fungicide. Using with oils or adjuvants may damage plant. Group 12 fungicide. 12-hr reentry.
- Mirage at 1 to 2 fl oz/1,000 sq ft. Group 3 fungicide. 12-hr reentry.
- PropiMax EC at 0.37 to 0.73 fl oz/1,000 sq ft. Group 3 fungicide. 12-hr reentry.
- ProStar 70 WG at 1.5 oz/1,000 sq ft. Group 7 fungicide. 12-hr reentry.
- Tourney EZ at 0.37 to 0.44 oz/1,000 sq ft. plus other fungicides. 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.
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.
- Exteris Stressgard at 2 to 6 fl oz/1,000 sq ft. Group 7 + 11 fungicide. 12-hr reentry.
- Headway at 1.5 to 3 fl oz/1,000 sq ft. Do not use with silicone-based surfactants or EC formulations. Group 3 + 11 fungicide. 12-hr reentry.
- Heritage Action at 0.2 to 0.4 oz/1,000 sq ft. Group 11 + P1 fungicide. 12-hr reentry.
- Instrata at 8 to 11 fl oz/1,000 sq ft. Do not use on fine fescue. See label for tank mix incompatibilities. Group 3 + 12 + M5 fungicide. 12-hr reentry.
- Premion at 6 to 8 fl oz/1,000 sq ft. Group 3 +14 fungicide. Reentry when sprays have dried.
- Renown at 2.5 to 4.5 fl oz/1,000 sq ft. Group M5 + 11 fungicide. 12-hr reentry.
Reference Burpee, L., and Martin, B. 1992. Biology of Rhizoctonia species associated with turfgrasses. Plant Disease 76:112-117.