The label is the law. Rates and restrictions below are taken from the product labels listed under Sources. Your product's own label governs; read it before you mix or apply. Mixing calculator · Disclaimer
- Active ingredient
- Chlorsulfuron
- Chemical class
- Sulfonylurea; WSSA Group 2 acetolactate synthase (ALS) inhibitor.[2][1]
- Mode of action
- WSSA Group 2: Acetolactate synthase (ALS) / AHAS inhibitors (sulfonylureas)[2][1]
- Signal word
- Telar XP Herbicide (also sold as Marshal Chlorsulfuron): Caution[1]
Keep it away from lawns and tree roots
The label forbids use on lawns, walks, driveways, golf courses, athletic fields, sod farms or other fine turf. It also bars spraying or flushing equipment anywhere desirable tree or shrub roots may reach.[1]
Treated soil that blows or washes onto cropland can injure most crops except small grains. Don't spray dry, powdery or sandy soil when wind erosion is likely.[1]
Waiting to reseed grass
On industrial turf, wait 6 months before planting grass seed. For pasture species the label lists waits of about 1 to 6 months, depending on the grass, the rate and soil pH; late-season sprays start that clock the next spring.[1]
Where it is used
Treat perennial weeds at the bud-to-bloom stage or as fall rosettes, and annual weeds while they are small. Warm, moist weather after spraying speeds it up; cold or drought slows it.[1]
Expect a slow kill. Growth slows and growing points turn reddish-purple in 2 to 3 weeks, and the weeds die within 4 to 6 weeks.[1]
Fill the tank a quarter to a third with water, add the product with agitation for at least 5 minutes, then finish filling. Spray within 24 hours and avoid acidifying adjuvants.[1]
Clover, alfalfa and other broadleaf forage will be badly stunted. Ryegrass can be severely injured and fescues may yellow, so test a small area first on unfamiliar grass.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| Telar XP Herbicide (also sold as Marshal Chlorsulfuron)[1] | Environmental Science U.S., LLC | 101563-176 | 75.0% | dry flowable | Caution |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Telar XP Herbicide (also sold as Marshal Chlorsulfuron) | Permanent pasture, rangeland and Conservation Reserve Program land | Musk thistle, henbit, field pennycress, wild parsnip, whitetop and other listed broadleaf weeds | 0.25–1.0 oz product per acre[1] Lower rates give shorter control of the easiest weeds; tougher weeds are listed at higher rates. No more than 1.33 oz per acre per year, up to 3 applications at least 14 days apart. |
| Telar XP Herbicide (also sold as Marshal Chlorsulfuron) | Non-crop sites: roadsides, rights-of-way, fence rows, farmyards, industrial sites | Canada thistle, bull thistle, poison-hemlock, common mullein, curly dock, Dalmatian toadflax and other listed weeds | 0.25–2.6 oz product per acre[1] Broadcast use is capped at 2.6 oz per acre per year. Dalmatian toadflax takes 2 to 2.6 oz in at least 24 gallons of water per acre. |
| Telar XP Herbicide (also sold as Marshal Chlorsulfuron) | Spot treatment in pasture, range and CRP land | Labeled broadleaf weeds | 1 g product per gallon of water[1] Use the measuring guide packed with the container, add a surfactant, and wet the whole weed; that works out to roughly 35 gallons of solution per acre. |
Safety and environmental hazards
People
Signal word CAUTION: harmful if swallowed. Anyone mixing or spraying it wears a long-sleeved shirt, long pants, shoes, socks and waterproof chemical-resistant gloves.[1]
Pets
Keep people and pets out of the area while spraying, and don't let them back in until the spray has dried.[1]
Bees and pollinators
There is no direct bee toxicity statement. The label warns that killing plants near the target can reduce forage and habitat for pollinators, so keep drift on target.[1]
Fish and water
Don't apply to water or wet ditches. The label says chlorsulfuron can leach to groundwater in permeable soils and run off to surface water for weeks; skip spraying if rain is expected within 48 hours.[1]
Common questions
- Can I use chlorsulfuron on my lawn?
- No. Telar XP's label specifically prohibits lawns and other high-maintenance turf, and warns against use where roots of desirable trees or plants extend.[1]
- Do animals need to stay off a pasture sprayed with Telar XP?
- No. At up to 1.33 oz per acre per year there are no grazing or haying restrictions for any livestock, including lactating animals.[1]
- How long does chlorsulfuron take to kill weeds?
- Several weeks. Leaves slow and growing points redden within 2 to 3 weeks, and plants die in 4 to 6 weeks.[1]
Sources
- U.S. EPA Pesticide Product Label System, “Telar XP Herbicide label, EPA Reg. No. 101563-176 (EPA-stamped, June 25, 2026).” www3.epa.gov/pesticides/chem_search/ppls/101563-00176-20260625.pdf (accessed 2026-10-06)
- Weed Science Society of America, “Summary of Herbicide Mechanism of Action According to the Weed Science Society of America.” wssa.net/wp-content/uploads/WSSA-Mechanism-of-Action.pdf (accessed 2026-10-06)