The label is the law. Read your product's label before you mix or apply; the rates here come from the labels listed under Sources.
- Active ingredient
- Dithiopyr (CAS 97886-45-8)
- Chemical class
- Pyridine; WSSA Group 3 microtubule assembly inhibitor.[2][1]
- Mode of action
- WSSA Group 3: Microtubule assembly inhibitors (pyridines)[2][1]
- Signal words
- Dimension Ultra 40WP Specialty Herbicide: Caution[1]
Dimension 0.25G Turf and Ornamental Herbicide (residential sub-label; also sold under distributor brand names): Caution[3]
Reseeding after dithiopyr
Reseeding, overseeding or sprigging within 3 months of a single application, or 4 months after a heavier sequential program, may keep desirable grass from establishing. The exception is overseeding bermudagrass with perennial ryegrass 8 weeks after application.[1]
Which grasses tolerate it
Tolerant turf includes Kentucky bluegrass, tall and fine fescue, perennial ryegrass, bermudagrass, St. Augustinegrass, zoysiagrass, centipedegrass and others, but some fine fescue and creeping bentgrass varieties are injured, it isn't for colonial bentgrass or putting greens, and it will prevent annual bluegrass from germinating.[1]
Where it is used
Activate it with at least ½ inch of rain or irrigation before most weeds germinate. For young crabgrass that's already up, wait 6 hours before irrigating so the spray can work on the leaves.[1]
In cool-season regions, early postemergence control works when crabgrass is still under 5 leaves, before it starts to tiller; in warm-season regions the full rate has controlled crabgrass through the 3- to 5-tiller stage.[1]
Turf must be well established, with at least two mowings after seeding, sodding or sprigging; don't apply to new sod until it has rooted and the edges have filled in.[1]
Do core aeration or verticutting before applying, not after, and don't use clippings from treated turf as mulch around vegetables or fruit trees.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| Dimension Ultra 40WP Specialty Herbicide[1] | Corteva Agriscience, LLC | 62719-445 | 40.0% | wettable powder in water-soluble pouches | Caution |
| Dimension 0.25G Turf and Ornamental Herbicide (residential sub-label; also sold under distributor brand names)[3] | Corteva Agriscience LLC | 62719-429 | 0.27% | granules | Caution |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Dimension Ultra 40WP Specialty Herbicide | Established lawns, sports turf, golf fairways and roughs, sod farms, landscape ornamentals | Crabgrass, goosegrass, Poa annua, spurges, oxalis, henbit and other annual weeds | 0.23–0.46 oz product per 1,000 sq ft[1] That is 2 to 4 water-soluble pouches (0.25 to 0.5 lb dithiopyr) per acre, single or sequential applications 5 to 10 weeks apart, in at least 0.5 gallon of water per 1,000 sq ft. No more than 1.5 lb dithiopyr per acre per year. |
| Dimension 0.25G Turf and Ornamental Herbicide (residential sub-label; also sold under distributor brand names) | Established lawns (Dimension 0.25G granules) | Crabgrass (including young emerged crabgrass) and other listed annual grasses and broadleaf weeds | 1.1–4.3 lb product per 1,000 sq ft[3] North: 1.1 lb for 2 to 3 months of crabgrass control, 1.5 lb for 3 to 4. South: 1.6 lb, or 1.9 to 2.2. Young emerged crabgrass: 1.9 to 4.3 lb. No more than 12.9 lb a year. |
| Dimension 0.25G Turf and Ornamental Herbicide (residential sub-label; also sold under distributor brand names) | Established landscape ornamental beds (Dimension 0.25G granules) | Listed annual grasses and broadleaf weeds, before they sprout | 4.3 lb product per 1,000 sq ft[3] About 6.9 oz per 100 sq ft, all at once or split into two applications 5 to 10 weeks apart. |
How to apply it, step by step
1. Protective gear
- It carries the CAUTION signal word and causes moderate eye irritation: keep the granules out of your eyes and off your clothing.[3]
- Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, using tobacco or using the toilet.[3]
2. Before you spray
- It prevents crabgrass and other listed annual grasses and broadleaf weeds before they sprout, and it also kills crabgrass seedlings up to 4 weeks after they germinate, about the 3-leaf stage. It won't control crabgrass that has started to spread (tiller) or other weeds that are already up.[3]
- Use it only on established lawns of the listed grasses: creeping bentgrass, Kentucky bluegrass, fine and tall fescue, perennial ryegrass, bahiagrass, bermudagrass, buffalograss, carpetgrass, centipedegrass, St. Augustinegrass and zoysiagrass. A new lawn needs a vigorous root system and at least two mowings first, though Kentucky bluegrass, perennial ryegrass and tall fescue can be treated two weeks after the first sign of germination.[3]
- Do any core or spike aeration or verticutting before you apply it, and let the turf recover from that work first.[3]
- In beds, use it only around established ornamentals, on soil free of weeds, clods and leaves; pull or kill existing weeds first.[3]
- Spread it in spring before crabgrass germinates (or up to 4 weeks after), or from late August through November for winter weeds, followed by a spring application for season-long crabgrass control.[3]
3. Mixing
- There's nothing to mix. Calibrate a drop or rotary spreader made for granular herbicides; for the most even coverage, spread half the amount in one direction and the other half at a right angle to it.[3]
4. Applying
- Lawns in the North: 1.1 lb per 1,000 sq ft for 2 to 3 months of crabgrass control, or 1.5 lb for 3 to 4 months. In the South: 1.6 lb, or 1.9 to 2.2 lb for longer control. To kill young crabgrass that has already come up, use 1.9 to 4.3 lb.[3]
- Ornamental beds: 4.3 lb per 1,000 sq ft (about 6.9 oz per 100 sq ft), in one application or split into two 5 to 10 weeks apart. Never exceed 4.3 lb per 1,000 sq ft in one application or 12.9 lb a year; in New York, lawns are limited to 2.1 lb a year.[3]
- Apply within a few days after mowing and wait a few days before mowing again. Avoid streaks, skips and overlaps, and don't spread it when wind could carry granules onto sensitive plants.[3]
5. After you spray
- Water it in: about ½ inch of rain or sprinkler irrigation activates it, and weed control can be erratic if it isn't activated within 30 days. In beds, irrigate right away to wash granules off ornamental foliage.[3]
- Keep people and pets off the area until the dust has settled. Don't use the clippings as mulch around vegetables or fruit trees, don't disturb treated bed soil, and don't apply another herbicide to the beds within 4 weeks.[3]
- Wait 10 weeks before reseeding, overseeding or sprigging after a single application, 16 weeks after a split program totaling 4.3 lb or more, and 12 weeks after a fall application.[3]
First aid
- The label's first aid covers the eyes: hold them open and rinse slowly and gently with water for 15 to 20 minutes, taking out contact lenses after 5 minutes, then call a poison control center or doctor. For emergency medical treatment information it lists 1-800-992-5994, day or night.[3]
Storage, spills and disposal
Safety and environmental hazards
People
Signal word CAUTION: causes eye irritation and is harmful if absorbed through the skin. Avoid breathing dust; applicators wear chemical-resistant gloves.[1]
Pets
The label's hazards to humans and domestic animals are eye irritation and skin absorption; avoid contact with skin, eyes and clothing. The granule label adds: keep people and pets off the treated area until the dust has settled.[1][3]
Bees and pollinators
The Dimension Ultra 40WP label's environmental warnings concern fish and aquatic life rather than bees; the Dimension 0.25G granule label adds that the product is toxic to plants and can harm forage and habitat for pollinators next to the treated site.[1][3]
Fish and water
Toxic to fish and highly toxic to other aquatic organisms including oysters and shrimp. Take care on turf next to water, and don't apply when weather favors drift.[1]
Common questions
- Can dithiopyr kill crabgrass that's already up?
- Yes, while it is young. The label gives early postemergence control before tillering in cool-season areas and through the 3- to 5-tiller stage in warm-season areas at the full rate.[1]
- How long after dithiopyr can I overseed?
- The label warns that seeding within 3 months of a single application, or 4 months after sequential applications, may inhibit new grass.[1]
- Does dithiopyr need to be watered in?
- Yes, for preemergence control: at least ½ inch of rain or irrigation activates it.[1]
- How much Dimension 0.25G per 1,000 square feet?
- In the North, 1.1 lb for 2 to 3 months of crabgrass control or 1.5 lb for 3 to 4 months; in the South, 1.6 lb or 1.9 to 2.2 lb. Killing young crabgrass that has already come up takes 1.9 to 4.3 lb, and a year's total can't exceed 12.9 lb.[3]
- How long after Dimension granules can I reseed?
- The residential granule label says to wait 10 weeks after a single application, 16 weeks after a split program totaling 4.3 lb or more, and 12 weeks after a fall application.[3]
Sources
- U.S. EPA Pesticide Product Label System, “Dimension Ultra 40WP Specialty Herbicide label, EPA Reg. No. 62719-445 (EPA-stamped, Apr. 18, 2017).” www3.epa.gov/pesticides/chem_search/ppls/062719-00445-20170418.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)
- U.S. EPA Pesticide Product Label System, “Dimension 0.25G Turf and Ornamental Herbicide (residential sub-label) label, EPA Reg. No. 62719-429 (EPA-stamped, Apr. 15, 2022).” www3.epa.gov/pesticides/chem_search/ppls/062719-00429-20220415.pdf (accessed 2026-11-08)