Reference
Active ingredients
Every guide here tells you to buy for the active ingredient rather than the brand. This is the other half of that advice: 17 actives, what each one controls, what it does not, and the 50 products we have read labels for that contain them.
An active only gets a page when two things are true — someone has written the chemistry, and at least two products whose label we actually opened contain it. Actives we hold products for but have not written up yet are absent rather than thin.
Broadleaf and woody weeds
Synthetic auxins — the class behind almost every selective lawn weed killer.
- Triclopyr11 products
Pyridine carboxylic acid (synthetic auxin)
A synthetic auxin — it mimics a plant growth hormone, so the plant grows itself to death rather than being burned.
- 2,4-D7 products
Phenoxy (synthetic auxin)
The oldest selective broadleaf herbicide still in wide use, and the backbone active of nearly every three-way lawn product.
- Dicamba6 products
Benzoic acid (synthetic auxin)
A synthetic auxin that partners 2,4-D in most three-way products, covering weeds the phenoxy alone handles poorly.
Grasses, selectively
Kill a grass inside something you want to keep, which is the hardest job in turf.
- Fluazifop-P-butyl5 products
Aryloxyphenoxypropionate (ACCase inhibitor, Group 1)
A grass-selective herbicide that blocks an enzyme only grasses depend on, which is what lets it kill a grass inside a broadleaf planting.
- Clethodim2 products
Cyclohexenone oxime — a DIM (ACCase inhibitor, Group 1)
A grass-selective herbicide from the DIM family, and both labels we read print GROUP 1 on the front panel. It blocks an enzyme grasses depend on and broadleaf plants do not.
- Mesotrione2 products
Triketone (HPPD inhibitor, Group 27)
A bleaching herbicide — it blocks pigment synthesis, so treated weeds turn white before they die.
Before the weed appears
Soil residual. One is a pure barrier; the other also works on what has already come up, and both are dated by the soil rather than the calendar.
- Prodiamine3 products
Dinitroaniline (mitotic inhibitor, Group 3)
A long-residual pre-emergent that forms a barrier in the top layer of soil and kills seedlings as they germinate through it.
- Atrazine2 products
Triazine (photosystem II inhibitor, Group 5)
A residual triazine herbicide with an unusual property for a lawn product: it works both before and after a weed emerges, which is why the Southern weed-and-feed bag is built around it.
Everything green
Non-selective. One kills to the root and takes its time; the other burns fast and reaches nothing.
- Glyphosate6 products
Glycine (EPSP synthase inhibitor)
A non-selective systemic herbicide that blocks an enzyme pathway plants have and animals do not.
- Glufosinate-ammonium2 products
Phosphinic acid (glutamine synthetase inhibitor, Group 10)
A non-selective herbicide that is not glyphosate and does not behave like it. The label we read names the mechanism itself: a Group 10 herbicide, a glutamine synthetase inhibitor, which makes ammonia accumulate in the tissue the spray wets.
- Diquat dibromide2 products
Bipyridylium (photosystem I inhibitor)
A fast contact herbicide, and in home products always a minor partner rather than the headline active — the two we review carry it at 0.073% and 0.12%.
Fungal disease
Two classes, and owning both is a resistance strategy rather than an upsell.
- Azoxystrobin4 products
Strobilurin (QoI, FRAC 11)
A systemic fungicide that interrupts fungal respiration, sold to homeowners mostly as a granular.
- Propiconazole4 products
Triazole (DMI, FRAC 3)
A systemic fungicide from a different class to the strobilurins, which is what makes the two a usable rotation pair.
Insects and animals
Where the gap between what a bag says and what it reaches is widest.
- Bifenthrin4 products
Pyrethroid (sodium channel modulator)
A contact insecticide, and the cheapest and most widely sold active in lawn insect control.
- Lambda-cyhalothrin2 products
Pyrethroid (sodium channel modulator)
A second-generation pyrethroid with the same reach and the same limits as bifenthrin.
- Bromethalin5 products
Neurotoxicant rodenticide
A rodenticide, sold for moles in a bait shaped and scented as an artificial earthworm rather than as grain.
Legume and food-plot use
Selective over clover and alfalfa, which is why these never appear on a lawn label.
- Imazethapyr2 products
Imidazolinone (ALS inhibitor, Group 2)
A selective herbicide used over legumes — the reason it appears in food-plot rather than lawn products.
Same active does not mean same product. Concentration, labelled sites and species tolerances all vary between two bottles of the same chemistry, and a three-part registration number means a label that has been narrowed. Reading a label takes two minutes and settles all three.