Goodbye July! Scouting for ABW, Brown Patch, Type 1 Fairy Ring and 123rd Western Amateur
Goodbye July! Because if you are a grower of creeping bentgrass at low heights of cut (putting greens) it would have amounted to one of the most challenging 31 days in your golf course superintendent career. But it was the overall pattern of the 2025 growing season up to now that really got us. An especially hot, humid July followed an unusually cool winter and spring. It amounted to holding down the growth of creeping bentgrass. Optimal bentgrass root growth — necessary for normal shear strength and many other physiological benefits we count on like the storage of necessary carbohydrates — had to wait. In total we lost two of our normal four weeks of critical growth that June gives us. Without deep roots then came a hot and furious July. Given preventive measures in place, a majority of issues were abiotic — wear (foot traffic and equipment) injury of golf greens was #1.
The final two weeks of July did bring some diagnostic excitement. Mainly due to a new pest called annual bluegrass weevil (ABW) in Chicago’s northern suburbs. This stem and crown-feeding pest was emerging as a new generation in its life cycle and five new courses were confirmed with ABW damage to fairways, collars and tees. July’s final heat also saw a plethora of fungal disease. One, a foliar blight called brown patch (Rhizoctonia solani) pounced on unprotected creeping bentgrass. But it’s the stuff below ground that’s always the most difficult for us to control. For example type 1 fairy ring — dead rings up to several feet in diameter on putting greens — is a recurring issue during periods of peak heat. But most of the time playing conditions remain just fine; a testament to education, hard work and dedication.
In a week we volunteered at the Western Amatuer at Skokie Country Club, and were reminded of how environmental stewardship and sustainability is now mainstream and continues to be practiced by golf course superintendents. Take walk around Skokie CC and you’ll see monarch butterflies among the milkweed and nests with bluebirds ready to fledge. And then the weather changed. The local Chicago headlines were, “Dangerous heat finally begins to break as scorching July comes to an end.” Golfers, spectators and grounds and greens crew members were happy in Glencoe — not to mention the ‘007’ creeping bentgrass greens. As forecast we all got a break — cool weather.
Weather
Scouting for ABW— Annual Bluegrass Weevil (Listronotus maculicollis)
The month of July saw a lot of turfgrass injury. But what was the causal agent? Sometimes the answer isn’t straight forward or is caused by several factors which can be abiotic or biotic.
Diagnostic possibilities that we must rule out
- Physiological (abiotic)
- Fungal Disease
- Insect Pest — ABW is new
- Nematodes
A new reality in the upper Midwest is that we now need to rule out damage from a recently introduced pest called annual bluegrass weevil (ABW). It was first identified in Chicago’s north suburbs in 2023 and has begun to spread to golf courses there — 5 new courses saw outbreaks last week.
ABW can rapidly cause fairways, tees or green collars look thinned and off color. In the not-so-distant future additional inputs (and timings) are going to be required to address ABW. This additional cost will need to be budgeted for by golf course superintendents. At an 18 hole golf course early estimates range anywhere from $10,000 to $20,000. In part the amount of product needed to treat for ABW depends on the how vulnerable you are or how much annual bluegrass (Poa annua) exists from tee to green.
References
Emergence of a new Illinois turf pest: The annual bluegrass weevil, University of Illinois
Annual Bluegrass Weevil, Penn State University
Scouting for Disease — Brown Patch (Rhizoctonia solani)
When you have a period of leaf wetness that lasts at least 10 hours along with warm nighttime temperatures (70s) you're going to recieve a quick lesson in epidemiology of the turfgrass-kind. Rhizoctonia solani is a soilborne fungus that can survive both as a saprophyte (feeds on organic matter in the upper thatch layer of turf) and, when conditions are right, as a parasite (causes a foliar blight of most cool season turfgrasses).
“Brown patch (caused by various Rhizoctonia and Rhizoctonia-like species) is a major summer disease for several cool-season turfgrass species, including creeping bentgrass (Agrostis stolonifera), colonial bentgrass (Agrostis capillaris), perennial ryegrass (Lolium perenne) and turf-type tall fescue (Schedonorus arundinaceus). This destructive summer disease can impact seasonal appearance, uniformity, density and green color, potentially requiring reseeding. Preventive fungicide applications can effectively suppress this disease, but implementing cultural management practices such as planting a resistant host or adapting optimized fertilization programs could reduce the overall need for fungicide applications.”
New research on brown patch in tall fescue has reinforced the known truth that the best way to prevent certain fungal diseases is by actively selecting for resistance during turfgrass breeding. At Purdue University researchers showed that newer turf type tall fescue cultivars selected for resistance to brown patch were able to decrease brown patch by 61% versus cultivars of other turfgrass species representing creeping bentgrass, colonial bentgrass and perennial ryegrass.
References
Jada Powlen et al. May, 2024. Brown patch severity as affected by cool-season turfgrass species, cultivar, and nitrogen rate. Crop Science
Jada Powlen et al. Sep, 2024. Brown patch severity among turfgrass species, cultivars and nitrogen rates. Golf Course Management (GCM)
Scouting for Disease — Type 1 Fairy Ring (various Basidiomycetes)
Without a doubt one of the most damaging turfgrass diseases that can set its foot on a golf course property is called fairy ring. During periods of peak heat during midsummer an aggressive form occurs. It is called type 1 fairy ring and differs from others visually because it kills the turf and causes dead rings. The other types which are less damaging are called type 2 (green rings) and type 3 (mushrooms or puff ball fruiting structures). You can have one type or a combination of the three depending on visual symptoms.
Solutions
- Wetting agents are very helpful to help reduce hydrophobicity in the soil which is associated with build up of fungal mycelium.
- Curative control of fairy ring is possible with SDHI fungicides but complete control is rarely observed — Pedigree, Velista, Xzemplar
- Newer DMIs are preferred because they will have less impact on plant growth when recovery is needed — Densicor, Maxtima, Rayora
- Fungicides must be watered-in immediately following application to the depth of the mycelium — waiting later in the day or evening to water-in may mean that a fungicide targeting fairy ring may not work at all.
Cultural and Chemical Recommendations for Fairy Ring
See page 18 in Chemical Control of Turfgrass Diseases 2024
123rd Western Amateur at Skokie Country Club
“The field features 156 invited players from across the world. They play 18 holes of individual stroke play on Tuesday and Wednesday, after which the field is cut to the low 44 scores and ties. The remaining players play 36 holes of individual stroke play on Thursday to determine the low 16 finishers. The “Sweet Sixteen” compete in match play on Friday and Saturday to decide a champion.”
The Western Amateur’s Sweet Sixteen represent
- 95 major championships since 1956
- 24 PGA TOUR Player of the Year Awards since 1990
- 11 FedExCup titles
- 14 PGA TOUR Rookie of the Year Awards since 2000
- 11 participants in the 2023 Ryder Cup
Behind the Scenes — Preparing Never Stops
Education & Communication by CDGA’s Green Committee
Milkweed and Monarchs by James Weisiger
“Over the years golf courses have taken the role of environmental conservation very seriously, and they continue to play and important part in supporting local ecosystems. One way they have done this is by incorporating milkweed into the golf course landscaping. “
Final Photos
“Asclepias is a genus of herbaceous, perennial, flowering plants known as milkweeds, named for their latex, a milky substance containing cardiac glycosides termed cardenolides, exuded where cells are damaged. Most species are toxic to humans and many other species, primarily due to the presence of cardenolides. However, as with many such plants, some species feed upon milkweed leaves or the nectar from their flowers. A noteworthy feeder on milkweeds is the monarch butterfly, which uses and requires certain milkweeds as host plants for its larvae.” for more on over 200 species see Wikipedia
