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
- Flumioxazin
- Chemical class
- Protoporphyrinogen oxidase (PPO) inhibitor, WSSA Group 14; seedlings die when they meet the treated soil and are exposed to sunlight.[1][2]
- Mode of action
- WSSA Group 14: Protoporphyrinogen oxidase (PPO/Protox) inhibitors[2][1]
- Signal word
- BroadStar Herbicide: Caution[1]
Plants to keep it away from
The label lists butterfly bush, summersweet clethra, winterberry holly, hydrangea, Japanese spirea and cape plumbago among sensitive species not to treat. It also warns of severe injury to many bedding plants and some herbaceous perennials such as hosta.[1]
Skip plants that are stressed, newly transplanted for less than 6 weeks, grown from seed less than a year ago, or shaped so leaves funnel granules to their base.[1]
Who may apply it
In residential and commercial landscapes, the label says BroadStar must be applied only by licensed commercial applicators. It also says not to use or store it in or around the home.[1]
Where it is used
Spread it on clean, weed-free soil or mulch before weeds germinate, then water in with ½ to ¾ inch within an hour. That activates it and washes granules off leaves.[1]
Apply only to dry foliage. Granules that stick to wet leaves or soft new growth can cause leaf spotting, so rub a hand over plants first to check for dew.[1]
Leave the soil surface undisturbed after treatment, since disturbing it can reduce control. Remove existing weeds first; it has only limited effect on emerged seedlings.[1]
Keep it off turfgrass, which it can injure, and away from bedding plants or beds that will be planted within three months.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| BroadStar Herbicide[1] | Valent U.S.A. LLC | 59639-128 | 0.25% | granule | Caution |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| BroadStar Herbicide | Established container, field and landscape shrubs, trees, ground covers, Christmas trees, non-bearing fruit and nut trees and vines, and bare ground non-crop areas | Annual grasses and broadleaf weeds from seed, including crabgrass, spotted spurge, bittercress, chickweed, oxalis and annual bluegrass | 3.4 lb product per 1,000 sq ft[1] The single labeled rate is 150 lb per acre, about 3.4 lb (2.4 quarts) per 1,000 sq ft or 1 cup per 100 sq ft. No more than 300 lb per acre a year, and the same plants no more than once every 8 weeks. |
Safety and environmental hazards
People
Signal word CAUTION: harmful if absorbed through the skin. Avoid breathing dust and spray mist; handlers wear long sleeves, long pants, chemical-resistant gloves, and shoes and socks.[1]
Pets
The skin-absorption warning covers people and domestic animals. Outside farm settings, keep others out of treated areas until the dust has settled.[1]
Bees and pollinators
The label has no bee-specific warning; its environmental statements focus on aquatic invertebrates and harm to nontarget plants from drift and runoff.[1]
Fish and water
Toxic to aquatic invertebrates. Do not apply to water or where runoff is likely, and don't apply in weather that favors drift.[1]
Common questions
- How much BroadStar per 1,000 square feet?
- About 3.4 pounds, or 2.4 quarts, which matches the label's single rate of 150 pounds per acre.[1]
- Does flumioxazin kill weeds that are already up?
- Not reliably. The label describes only limited postemergence activity on newly germinated seedlings and says to apply before weeds germinate.[1]
- How long does BroadStar last?
- With soil moisture maintained, the label gives 8 to 12 weeks of preemergence control, longest in cooler weather.[1]
Sources
- U.S. EPA Pesticide Product Label System, “BroadStar Herbicide label, EPA Reg. No. 59639-128 (EPA-stamped, May 27, 2020).” www3.epa.gov/pesticides/chem_search/ppls/059639-00128-20200527.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)