Mini ring

Rings or partial rings (quarter, half, or full circles) of yellow-to-bronze, thinned turf roughly 3-24 inches in diameter on bermudagrass putting greens, most visible in the lower canopy. Leaf blades themselves rarely show distinct lesions.

Yellowing or bronzing of turf in patches and/or thinned rings ranging from about 3 to 24 inches in diameter. Lower, older leaves may appear bleached or damaged. In severe cases the leaf sheaths, stolons, and nodes become necrotic, though distinct spots on the leaf blades themselves are uncommon. Symptoms peak from late July through October and can linger into spring.

Diagnosis typically requires lab culturing to confirm Waitea circinata var. zeae, since above-ground signs such as mycelium or sclerotia are not consistently visible in the field.

Mini ring is caused by the basidiomycete Waitea circinata var. zeae, long known as Rhizoctonia zeae. Unlike many foliar Rhizoctonia diseases, this pathogen colonizes leaves and sheaths as well as roots and other below-ground tissue, which is part of why fungicide applications must be watered in to reach the infection site. Its complete disease cycle and epidemiology are still not fully understood.

Most active during the heat of summer (July-September) when canopy temperatures reach 83-97 F, with symptoms often becoming most visible as growth slows in late summer and fall. Mechanical damage and low nitrogen fertility amplify symptom expression; the disease can persist at low levels into spring.