Methylated Seed Oil (MSO)

Not a pesticide — this is a spray adjuvant. It's added to a herbicide tank mix to improve how well the active ingredient sticks to and penetrates the leaf. It replaces non-ionic surfactants or crop oil in most post-emergence mixes and generally boosts performance.

Maker: Southern Ag
Active: Methylated seed oil blend + principal functioning agents (100%; exempt from tolerance under 40 CFR 180)
Signal: warning

Methylated Seed Oil (MSO) label — The shed bottle — Methylated Seed Oil (MSO), read straight off the label.

01Usage

What it's for and where it goes.

Purpose: Post-emergent herbicide enhancer. Improves cuticle penetration and coverage.
Pairs with (per label): Accent, Assert, Beyond, Chopper, Classic, Drive, Journey, Plateau, Poast, Pursuit, Raptor, Revolver, Ultra Blazer, and many others — including your Drive XLR8.
Rate: 1 to 4 pints per acre with post-emergent herbicides. Always add last to the spray mix and keep agitating.
Order of operations: Follow the herbicide label first; MSO is the add-on.

02Efficacy

How well it actually works.

University trials cited on-label show MSO improves post-emergence herbicide performance vs. plain surfactant in many cases.
Especially helpful on waxy/hard-to-wet weeds and in dry conditions.
Can increase crop/turf injury risk if over-applied in heat — more uptake cuts both ways.

03Best at killing

What it's genuinely strongest on in real use.

Not a killer — a spray booster. MSO's job is to break the leaf's waxy cuticle so the herbicide it is mixed with gets in. Where it earns its place is on waxy, hard-to-wet weeds and in dry conditions, and paired with Drive XLR8 (quinclorac) it is effectively required for the crabgrass kill. University trials cited on-label show MSO out-performing plain non-ionic surfactant for many post-emergents.
The trade-off: more uptake cuts both ways — over-applied in heat it can raise crop/turf injury.

04Dangers

What it can hurt — read this before you reach for it.

Signal word WARNING — causes skin and eye irritation; harmful if swallowed, inhaled, or in contact with skin.
If on skin: remove clothing, rinse skin 15–20 min. If in eyes: rinse cautiously 15–20 min, remove contact lenses.
Not toxic in the pesticide sense, but treat it as an irritant chemical.
Do not contaminate water when cleaning equipment.

05🐾 Dogs & re-entry

Pet safety — toxicity and how long until a dog can be back on it.

🐾 Pet safety — read before you let the dog out

Toxicity: MSO is not a pesticide, but it carries a WARNING signal word as a skin/eye irritant — "causes skin and eye irritation; harmful if swallowed, inhaled, or in contact with skin" (product label). It has no NPIC pesticide fact sheet because it has no pesticidal active.
The real dog risk is the tank it is in: MSO increases how much of the herbicide penetrates tissue, so re-entry timing should follow whatever herbicide it is mixed with (e.g. Drive XLR8's 12h REI / until-dry). On its own, treat spilled concentrate as an irritant and keep dogs off treated foliage until fully dry.

General guidance. Confirm the label's re-entry interval and ask your vet; when unsure keep dogs off until fully dry.

06Storage

How to keep it, and keep it separate.

Store in original container, cool/dry, away from children.
Oil-based; keep from extreme cold that could thicken it.
Long shelf life sealed.

landscape.gf.cx · chemicals · methylated-seed-oil · filed 2026-07-23 · read off the label — verify every rate against the booklet