Reflections on managing annual bluegrass

The Super Science research article highlights 20 journal articles on annual bluegrass, housed in a virtual issue titled Annual Bluegrass (Poa annua): A Troublesome Weed: Crop, Forage and Turfgrass Management. The online virtual issue was first published in March 2024 and was last updated in April 2025. Aaron Patton, Ph.D., at Purdue University, is the guest editor.

“Annual bluegrass is widely considered the most troublesome weed in managed turfgrass,” Patton explains. “Turf managers have relied for decades on cultural practices — things like mowing, fertility management and irrigation strategies — to try to give the desired turf species a competitive edge. The problem is that Poa annua is incredibly adaptable.”

According to Patton, those non-chemical approaches often fall short because annual bluegrass can thrive under a wide range of environmental conditions and because of its prolific seed production. “It produces enormous quantities of viable seed,” he says. “That seedbank allows it to reinfest turf year after year, even when managers think they’ve made progress.”

Because of that persistence, herbicides and plant growth regulators have become essential tools in many turf programs. “In lawns, golf courses and sports fields, chemical control is often necessary just to maintain acceptable playing quality,” Patton notes. “Plant growth regulators can help suppress seedhead production, while herbicides are used to selectively removePoa annua from desirable turf.”

But those tools come with their own challenges. “In some cases, repeated herbicide use has led to resistance,” Patton says. “That adds another layer of difficulty to managing a weed that’s already hard to control.”

Patton points to the value of pulling the science together in one place. “This collection of papers brings together both research and practical management guidance on annual bluegrass,” he explains. “The work spans everything from seed biology and ecology to plant growth regulator use, herbicide efficacy trials and large-scale surveys documenting herbicide resistance.”

Taken together, Patton says, the message is clear: Managing annual bluegrass isn’t about a single product or practice. “It’s a systems problem,” he concludes, “and understanding the biology and long-term behavior of Poa annua is critical to developing sustainable management strategies.”