By J. Scott McElroy – Professor, Turfgrass Management and Weed Science, Auburn University and James D. McCurdy – Professor and Extension Specialist, Turfgrass Management, Mississippi State University

Given the current climate surrounding federal funding discussions, we want to provide detailed information about research outcomes from the ResistPoa project. Our goal is transparency about what taxpayer dollars accomplished when this project received funding. For information regarding this project, please see http://resistpoa.org/.

Project Background

ResistPoa launched in 2018 as a nationwide initiative to tackle the growing problem of herbicide-resistant annual bluegrass (Poa annua) in turfgrass systems. This four-year, $5.7 million project, funded by the USDA Specialty Crop Research Initiative brought together 16 scientists from 15 universities across the country.

The project had clear objectives: develop better management practices for annual bluegrass control, map the extent of herbicide resistance nationwide, and create decision-support tools for turf practitioners. Essentially, we needed to understand how bad the resistance problem really was and give golf course superintendents, sports field managers, and other turf professionals the tools to fight back.

Annual bluegrass might seem like a small problem, but it’s not. This weed costs the turfgrass industry millions of dollars annually in control measures and lost playability. When herbicides stop working, managers face expensive reseeding, overseeding, and intensive maintenance schedules that strain budgets and resources.

Major Research Discoveries

Nationwide Resistance Survey

Our team’s biggest accomplishment was conducting the first comprehensive national survey of herbicide resistance in annual bluegrass. We collected and tested over 1,300 populations from turf sites across five different climate zones. The results were sobering—by 2023, we documented populations resistant to up to nine different herbicide modes of action.

This wasn’t just academic research. These findings gave turf managers concrete data about what to expect in their regions. Instead of guessing whether an herbicide might work, superintendents could now reference our maps and data to make informed decisions about their control programs.

Understanding Resistance Mechanisms

We dug deep into the science behind why annual bluegrass develops resistance. Through molecular analysis of dozens of populations, we identified specific genetic mutations that allow the weed to survive herbicide treatments. For example, we discovered a novel mutation in the β-tubulin gene that helps annual bluegrass resist popular pre-emergence herbicides like prodiamine.

Read the full project update in the Summer 2025 issue of Alabama Turf Times magazine – https://theturfzone.com/ata/?ascat=71&sub=issue&issue_id=9389&rti=true&rel=3