We all take for granted the fact that our very skilled superintendents prepare each spring to battle the usual summer turf issues. For example, fungal diseases require planned preventative applications every year and the usual contenders will include dollar spot, fairy ring and several root rots. If left unchecked, these turf maladies can negatively impact playability just like an unwanted divot ruining your lie…and fun.
However, a new challenge has emerged in recent years. Superintendents in the northern suburbs have faced a new and increasingly serious insect adversary known simply as ABW (annual bluegrass weevil). First identified in Manhattan, New York in 1957, ABW was first reported in Illinois in 2023 damaging putting green collars and approaches at two north suburban Chicago courses. ABW comes with real consequences for the closely mown turf and playing conditions you love – not to mention the budgets of our superintendents.
ABW is Unique to Golf Courses
This insect is a tiny oval-shaped beetle known as a weevil. ABW is a problem in turfgrass maintained at low mowing heights (half an inch or less), which means it is a unique problem for golf courses. It turns out that fairways, tees, green collars and green surrounds are all vulnerable to damage. Putting greens themselves are usually not negatively impacted by ABW because their intensive maintenance of daily mowing provides protection.
ABW Damage is Confusing
Aboveground turf damage occurs because ABW larvae feed inside a plant’s most vulnerable point – the crown and stem base. ABW turf damage, yellow-to-tan colored patches, can be easily confused with abiotic stress, like localized dry spot as well as fungal diseases, which often appear in patches. Though 2–3 generations can occur each year, damage is usually from first generation larvae feeding activity during June, July and August.
ABW Identification
Scouting is important because turf loss by ABW is during peak golf play. Superintendents and staff must consider ABW when patchy off-color symptoms quickly progress to patchy, thin, dead turfgrass. Although Poa annua is the preferred host, significant damage is documented in situations thought to be pure creeping bentgrass in Chicago. A simple soil flush with soapy water is the best field technique to scout for ABW adults. Additional sampling for larval enumeration requires shipping soil cores to a university laboratory.
ABW Control
Newer treatment options exist and their use lessens risk of insecticide resistance by ABW given older chemistries (e.g., pyrethroids) are known to be problematic. Rotation of chemistries designed with a unique mode of action is critical in the management of ABW. Timing is also very important for efficacious ABW control and relies on both a growing degree day (GDD) weather model and plant phenology. For example, overwintering ABW adults become active around late April, which coincides with a specific period of border forsythia bloom (½ yellow bloom and ½ leaf out).
Additional Expense
Golfers should know that ABW is not just another garden variety turf issue; it can be expensive and time intensive to manage. A 2017 peer-reviewed survey estimated that additional cost to control ABW at an 18-hole facility was $9,270. However, that survey is almost 10 years old and did not include additional labor for necessary repair work.
What to Expect
ABW isn’t going anywhere. As of 2025, ABW has increased to about 25 courses that have confirmed turf damage. The CDGA Turfgrass Program will continue to track ABW movement in the Chicago District. At this time, only golf courses in Chicago’s north suburbs, spanning an area of 40 miles, need to apply treatments for ABW.
Behind the Scenes
For the everyday player, discussion about ABW may not be interesting, but it is quietly becoming one of this area’s most talked-about pests among superintendents and turf professionals. As of 2023, they began to get up to speed on the lifecycle and behavior of ABW with an eye out for areas of turf decline.
We should appreciate the work behind the scenes because it just doesn’t stop with ABW. For golf course superintendents, it’s also about professionalism and commitment to the science of keeping our golf courses healthy, visually appealing, and ultimately play able for our continued enjoyment.
Robert Thies is chair of the CDGA Green Committee. He has been a CDGA Blue Coat since 2018.