The Growing Threat of Herbicide Resistant Weeds in Turf: A Global Overview
10 March 2026, Chicago: The battle against weeds in golf courses, sports fields, and residential lawns is becoming increasingly complex. Across the globe, turf managers are facing a formidable foe: herbicide-resistant weeds. The over-reliance on specific chemical treatments has accelerated the evolution of superweeds that can survive standard applications.
According to data tracking resistance in turf systems, a significant number of species—from the ubiquitous Annual Bluegrass to stubborn sedges—have developed immunity to multiple herbicide sites of action. Below is a comprehensive look at confirmed cases of herbicide-resistant weeds in turfgrass systems around the world.
Key Trends in Turf Resistance
- The Dominance of Poa annua: Annual Bluegrass is the most prevalent resistant weed on the list, appearing in Japan, Australia, and across the United States. It has developed resistance to at least seven different herbicide groups, including PSII inhibitors (Group 5), EPSP synthase inhibitors (Group 9/Glyphosate), and Microtubule inhibitors (Group 3).
- Geographic Hotspots: The United States has the highest number of documented cases, particularly in the Southeast (Tennessee, Georgia, Alabama, Mississippi, and the Carolinas). However, resistance is a truly global issue, with documented cases in Japan, New Zealand, and Australia.
- Multiple Resistance: One of the most alarming trends is the development of “Multiple Resistance.” In Tennessee (2013), a population of Poa annua was confirmed to be resistant to both ALS inhibitors (Group 2) and PSII inhibitors (Group 5), severely limiting chemical control options.
Herbicide Resistant Weeds in Turf
Below is the full dataset of confirmed herbicide-resistant weeds in turfgrass environments globally. The table is sortable by clicking on the column headers.
| # | Species | Common Name | Country | First Year | Site of Action / HRAC Group |
|---|---|---|---|---|---|
| 1 | Poa annua | Annual Bluegrass | Australia (Victoria) | 2009 | Unknown HRAC Group 27 (Legacy Z) |
| 2 | Poa annua | Annual Bluegrass | Japan | 1982 | PSII inhibitors – Serine 264 Binders HRAC Group 5 (Legacy C1 C2) |
| 3 | Soliva sessilis | Lawn Burweed | New Zealand | 1999 | Auxin Mimics HRAC Group 4 (Legacy O) |
| 4 | Poa annua | Annual Bluegrass | New Zealand | 2020 | Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A) |
| 5 | Poa annua | Annual Bluegrass | United States (Alabama) | 2012 | Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B) |
| 6 | Poa annua | Annual Bluegrass | United States (Alabama) | 2012 | Inhibition of Microtubule Assembly HRAC Group 3 (Legacy K1) |
| 7 | Cyperus compressus | Annual Sedge | United States (Alabama) | 2015 | Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B) |
| 8 | Eleusine indica | Goosegrass | United States (Georgia) | 1992 | Inhibition of Microtubule Assembly HRAC Group 3 (Legacy K1) |
| 9 | Digitaria sanguinalis | Large Crabgrass | United States (Georgia) | 2008 | Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A) |
| 10 | Chamaesyce maculata | Spotted Spurge | United States (Georgia) | 2014 | Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B) |
| 11 | Eleusine indica | Goosegrass | United States (Hawaii) | 2003 | PSII inhibitors – Serine 264 Binders HRAC Group 5 (Legacy C1 C2) |
| 12 | Plantago lanceolata | Buckhorn Plantain | United States (Indiana) | 2016 | Auxin Mimics HRAC Group 4 (Legacy O) |
| 13 | Poa annua | Annual Bluegrass | United States (Mississippi) | 1996 | PSII inhibitors – Serine 264 Binders HRAC Group 5 (Legacy C1 C2) |
| 14 | Poa annua | Annual Bluegrass | United States (Missouri) | 2010 | Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G) |
| 15 | Digitaria ischaemum | Smooth Crabgrass | United States (New Jersey) | 1996 | Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A) |
| 16 | Poa annua | Annual Bluegrass | United States (North Carolina) | 1995 | PSII inhibitors – Serine 264 Binders HRAC Group 5 (Legacy C1 C2) |
| 17 | Poa annua | Annual Bluegrass | United States (North Carolina) | 1997 | Inhibition of Microtubule Assembly HRAC Group 3 (Legacy K1) |
| 18 | Eleusine indica | Goosegrass | United States (Tennessee) | 1988 | Inhibition of Microtubule Assembly HRAC Group 3 (Legacy K1) |
| 19 | Poa annua | Annual Bluegrass | United States (Tennessee) | 2007 | Inhibition of Microtubule Assembly HRAC Group 3 (Legacy K1) |
| 20 | Poa annua | Annual Bluegrass | United States (Tennessee) | 2011 | Inhibition of Enolpyruvyl Shikimate Phosphate Synthase HRAC Group 9 (Legacy G) |
| 21 | Poa annua | Annual Bluegrass | United States (Tennessee) | 2013 | Multiple Resistance: 2 Sites of Action Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B) PSII inhibitors – Serine 264 Binders HRAC Group 5 (Legacy C1 C2) |
| 22 | Poa annua | Annual Bluegrass | United States (Virginia) | 2001 | PSII inhibitors – Serine 264 Binders HRAC Group 5 (Legacy C1 C2) |
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