Unusual yellow ring symptoms are being observed on putting greens and fairways across New England. Multiple diseases that display a similar appearance are active, making accurate diagnosis critical. One or more of the following could be at work:
1. Yellow Patch (“Cool-Season Brown Patch”)
Causal agent: Rhizoctonia cerealis
Hosts: Bentgrass, Poa annua, ryegrass
Conditions: Cool, wet weather (≈40–60°F; early spring/late fall)
Key symptoms:
- Yellow to light tan patches (circular or irregular)
- Turf appears chlorotic (yellowed) rather than blighted
- No smoke ring
- Leaf lesions: tan with darker margins
Takeaway: Occurs in cooler conditions; primarily yellowing, not severe necrosis.
2. Brown Ring Patch (Waitea Patch)
Causal agent: Waitea circinata var. circinata
Hosts: Primarily Poa annua greens
Conditions: Cool–moderate temps (≈60–75°F), often low nitrogen
Key symptoms:
- Distinct rings (yellow/orange/brown), often “frog-eye” (green center)
- Rings range from inches to >1 ft
- Turf inside ring often remains green
Takeaway: Well-defined rings and green centers, often linked to low N fertility.
3. Another, emerging “yellow ring” disease (under investigation, based on Dr. John Inguagiato, University of Connecticut, 2024 Extension update)
Status: Newly observed, not fully identified
Observed in: Connecticut and broader New England
Hosts: Primarily Poa annua greens
Key symptoms:
- Thin yellow rings (1–2 in. wide; 4–24 in. diameter)
- Often with green centers
- Symptoms at stem base and older leaves
Important findings:
- Microscopy shows clamp connections → indicates a basidiomycete, not Waitea or typical Rhizoctonia
- Genetic testing suggests a previously unidentified fungus
Management:
- Control is uncertain at this time
- Fungicides targeting basidiomycetes (QoIs, flutolanil, penthiopyrad, fluoxapyroxad) may provide suppression
- Field trials ongoing
Takeaway: Looks like brown ring patch, but different pathogen—diagnosis required.
Practical Guidance
- Multiple diseases can produce similar yellow ring symptoms right now
- Visual diagnosis alone is not reliable
- Lab confirmation (microscopy + molecular testing) is recommended
- If symptoms are present, submit samples for diagnosis (Dr. Geunhwa Jung, #206 Paige Lab, 161 Holdsworth Way, University of Massachusetts Amherst, MA 01003). For other turf issues, UMass Extension’s Plant Diagnostic Lab is always an option.
Bottom Line
Not all yellow rings are the same this spring. Distinguishing between yellow patch, brown ring patch, and the emerging “yellow ring” disease is essential for effective management.
Submitted by: graduate student GwangJae Lim & Dr. Geunhwa Jung