Dithiopyr (Dimension) Pre-Emergent Herbicide

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Target Pests / Scope

Crabgrass (pre-emergent AND early post-emergent up to tillering), goosegrass, foxtail, annual bluegrass, spurge, chickweed, henbit, and other annual weeds. The early post-emergent crabgrass activity is the key differentiator from prodiamine and pendimethalin.

Products and Recommendations

Dimension 2EW (Corteva - professional liquid), Dimension Ultra 40WP (professional), Scotts Halts Crabgrass Preventer with Dimension, Bonide Crabgrass and Weed Preventer (some formulations), Lesco Dimension. Available in both sprayable and granular formulations.

Safety

Low mammalian toxicity. Low toxicity to birds, fish, and invertebrates at labeled rates. Does not stain concrete (unlike prodiamine) - a significant advantage for homeowners applying near driveways and sidewalks.

The forgiveness factor: If you applied your pre-emergent a week or two late and tiny crabgrass seedlings are already emerging, dithiopyr can still kill them. No other pre-emergent herbicide can do this. This is why many lawn care professionals recommend Dimension over Barricade for homeowners.

Example

0.5 oz

per gallon

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Detailed Guide

Why Dimension is ideal for homeowners: Timing pre-emergent applications perfectly is stressful for homeowners. Prodiamine (Barricade) has ZERO post-emergent activity - if you miss the window, the crabgrass is through. Dithiopyr (Dimension) gives you a 2-3 week grace period where it can still kill very young crabgrass plants. This makes it significantly more forgiving.

How early post-emergent activity works: Dithiopyr is absorbed by both roots AND young shoots. When a crabgrass seedling has just emerged but has not yet produced its first tiller (side shoot), dithiopyr can still disrupt cell division and kill it. Once the plant reaches the 2+ tiller stage, it has outgrown vulnerability.

Residual comparison: Dithiopyr provides approximately 3-4 months of pre-emergent control, compared to prodiamine at 5-6 months. For most northern climates, this is sufficient for the crabgrass season. In the deep South where crabgrass pressure lasts longer, prodiamine at the high rate or a split application of dithiopyr is preferred.

No staining: Unlike prodiamine (Barricade), dithiopyr does not stain concrete, pavers, or hardscapes. If your lawn borders sidewalks, driveways, or a pool deck, Dimension is the better choice purely for cosmetic reasons.

Overseed timing: Wait at least 8-12 weeks after dithiopyr application before overseeding. Check label for specific rate-dependent intervals.

Key takeaway: Dithiopyr was the first pre-emergent herbicide discovered to have meaningful early post-emergent crabgrass activity. This dual-mode capability made it the default recommendation for homeowner lawn care when it was introduced by Rohm and Haas (now Corteva) in 1991.

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Reviewed by Derek GiordanoContent reviewed by a licensed pest management professional. Last reviewed: April 2026.