Golf courses have reported a new and likely growing disease during humid summers and early autumns in recent years: Waitea patch, which is often mistaken for fairy ring.  Henry Bechelet, Technical Manager, ICL Turf and Landscape, explains how to diagnose the disease, what it does, how to avoid it and how to treat it.

Waitea patch is an emerging turf disease in the UK, caused by the fungal pathogen Waitea circinata var. circinata. While more commonly associated with warm-season regions, it is now being observed on golf courses and stadium turf across the UK and Ireland, particularly during humid summer and early autumn periods. In the US and Japan, where it was first reported in the early 2000s, it is known as Brown Ring Patch.

Even experienced turf professionals may be unfamiliar with the name and unsure how to pronounce it. Technically, it is “WAY-tee-uh” for Waitea, and “sir-SIN-uh-tuh” for circinata. Whether or not you choose to correct your colleagues is another matter.

Recognising Waitea patch on turf

Waitea patch usually appears as yellow to light-brown rings that expand in scalloped or uneven patterns. These symptoms are most common on closely mown turf such as greens and can resemble Type I fairy ring at a glance.

However, unlike fairy ring, Waitea does not develop deep in the soil profile. It colonises the thatch and upper rootzone, breaking down crown tissue and weakening turf from the base. Affected areas may become sunken, thin or necrotic, with ring diameters ranging from a few inches to over a metre.

A simple in-field diagnostic is to remove a turf plug and seal it in a plastic bag overnight. If active, white or buff-coloured mycelium may be visible on thatch or crown tissue by the next morning.

When and where it thrives

Waitea patch favours mild to warm conditions with persistent surface moisture. It becomes active around 10°C and continues developing into the mid-20s, with an optimum near 25 to 30°C. In UK terms, this places the disease risk squarely in humid summer and early autumn periods.

Key triggers include:

• Prolonged leaf wetness or dew

• High humidity and poor airflow

• Moisture stress or compacted soils

• Low nitrogen nutrition

• Excessive thatch.

Shaded, sand-based greens with tight surfaces and poor thatch control are especially vulnerable.

Why it matters

Although not yet widespread, Waitea patch in serious cases has the potential to cause lasting disruption to playing surfaces. The disease can persist for weeks and leaves sunken rings that affect ball roll and visual quality.

Recovery is slow because crown tissue is the primary target. Unlike foliar diseases, Waitea’s damage cannot be removed through mowing. If left unmanaged, patches may coalesce and lead to extensive thinning or surface instability.

Cultural management strategies

Good agronomic practice is the first line of defence. Focus on reducing turf stress and managing leaf wetness.

Key strategies include:

• Maintain balanced nitrogen nutrition (for example, 2-3 kg N/ha/week during the growing season)

• Reduce thatch and compaction through aeration and sand topdressing

• Remove morning dew and improve airflow through pruning or use of turf fans

• Apply moisture management products such as H2Pro TriSmart or Qualibra to help reduce surface water holding and improve consistency.

• Avoid stressing turf during risk periods by holding back on aggressive mowing.

Chemical control options

At present, no fungicides in the UK or Ireland are approved specifically for Waitea circinata. However, international research shows that several broad-spectrum actives are effective in reducing symptoms when used preventively:

• QoI (strobilurin): such as azoxystrobin

• DMI (triazole): such as difenoconazole

• SDHI: such as Solatenol

• Phenylpyrrole: such as fludioxonil

Although Waitea may not be listed on UK product labels, fungicides effective against Rhizoctonia solani and other brown patch-type diseases may offer cross-protection. Examples include Heritage or Ascernity, applied in advance of symptom development. Always consult the label and a technical advisor before making off-label applications.

Looking ahead

With hot and humid summer conditions becoming more common, Waitea patch may become a more consistent challenge for turf managers. Monitoring for symptoms, managing surface moisture and maintaining plant health will be key to reducing impact.

For more information, visit icl-growingsolutions.com