Brown ring patch / Waitea patch

What to look for

• Separate or overlapping yellow rings, sometimes with greener grass remaining inside the affected edge.
• Ring margins becoming light brown or reddish as affected plants deteriorate.
• A slightly sunken ring where underlying thatch has broken down; damage can extend beyond the leaf.

Check the grass and site

Primarily wintergrass (Poa annua) on closely mown golf greens, with reports on creeping bentgrass and rough bluegrass. This guide is for professional managers assessing these grasses on fine-turf greens.

Confirm it before you treat it

Check the grass species, recent weather and whether the ring is depressed. Yellow patch favours cooler conditions, but the appearance overlaps. Photograph the whole pattern and affected plants, and obtain a turf diagnosis if rings persist or spread.

What to do next

1. Review nitrogen nutrition and correct genuine shortages without forcing excessive growth.
2. Plan thatch reduction and aeration while turf is growing actively, with the intensity matched to its condition.
3. Ease mowing stress where playing requirements allow, and track whether the affected margins recover.

Conditions matter more than dates.

Moist, overcast or foggy periods favour outbreaks across a fairly broad temperature range. Low nitrogen and excessive thatch are associated with greater risk. Closely cut turf is more vulnerable than turf maintained at a higher cut.