The herbicides listed in this section are intended for controlling weeds in ornamental landscape areas (not turfgrass) by commercial landscapers. These areas may include established trees, shrubs, rose and ground cover landscapes, bulbs, flower beds, and native wildflowers, and general maintenance around ornamental plantings. For homeowner use, please refer to other Extension guides https://extension.oregonstate.edu/catalog/pub/em8742.
Consult the herbicide label for information about the proper personal protective equipment, application timing and rate, tolerant desired landscape plants and susceptible weeds.
The following is a quick outline of the various herbicide types (non-selective, selective, pre-emergence and post-emergence) and group numbers.
Non-selective herbicides kill any plant after it is established (post-emergence). Some non-selective products have both pre- and post-emergence effects.
Selective herbicide target specific weeds while leaving desired plants unharmed. Selective herbicides can be used to target unwanted broadleaf plants, grasses, sedges, and annuals. Selective herbicides are typically used for post-emergence control.
Post-emergence herbicides kill plants after they have established. These herbicides can be non-selective which are often used for spot treatments (not broadcast application) in landscaping areas. Selective post-emergence herbicides are also available.
Pre-emergence herbicides kill plants as they are germinating and shortly after germination. Generally, these herbicides must be applied before weeds germinate in the spring or fall. Plants seeded in areas treated with pre-emergence herbicides typically will not germinate.
Site of action group numbers for the herbicides listed in this section: 0: unknown, 1:, 2: ALS inhibitor, 3: microtubule assembly inhibitor, 6: photosystem II inhibitor, 9: EPSP synthesis inhibitor 10: glutamine synthesis inhibitor, 14: PPO inhibitor, 15: very long-chain fatty acid inhibitor, 22: HPPD enzyme inhibitor, 29: Cellulose biosynthesis inhibitor. In the event of herbicide resistance apply products with a different site of action (group number).
Caution! Information provided in this handbook is not intended to be a complete guide to herbicide use. Before using any chemical, read the recommendations on the label. Before a chemical can be recommended for a specific use, it must be thoroughly tested.
The recommendation on the manufacturer’s label, when followed, can prevent many problems from arising from the wrong use of a chemical.
Note Herbicides must be applied at the correct rate and time to selectively control weed growth with minimal chance for injury to landscape plants. Obtain more consistent results by reading the herbicide label and other information about the proper application and timing of each herbicide. Calibrate your equipment precisely and verify exact application rates, especially to irregular landscape sites.
Non-selective Post-emergence Herbicides
|
Common name |
Trade Name |
Chemical family |
Site of action (group) |
|
diquat |
Reglone |
Bipyridilium |
22 |
|
EPTC |
Eptam 7E |
Thiocarbamate |
15 |
|
glufosinate ammonium |
Finale |
Phosphinic acid |
10 |
|
glyphosate |
numerous |
Organophosphate |
9 |
|
pelargonic acid |
Scythe |
Carboxylic acid |
0 (unknown) |
Selective Post Emergence Herbicides
(see label for appliable areas and affected weeds)
|
Common name |
Trade Name |
Chemical family |
Site of action (group) |
Selectively controlled weed(s) |
|
bentazon |
Basagran |
Benzothiadiazole |
6 |
Annual broadleaf weeds and yellow nutsedge |
|
clethodim |
Envoy Plus and others |
Cyclohexanedione |
1 |
Perennial and annual grasses |
|
fenoxaprop ethyl |
Acclaim Extra |
Aryloxyphenoxy propionate |
1 |
Annual grasses |
|
fluazifop P-butyl |
Fusilade and Ornamec |
Aryloxyphenoxy propionate |
1 |
Annual and perennial grasses |
|
halosulfuron- methyl |
Sedgehammer |
Sulfonylurea |
2 |
Nutsedge |
|
sethoxydim |
Segment |
Cyclohexanedione |
1 |
Perennial and annual grasses |
Pre-emergence Herbicides
(see label for appliable areas and affected weeds)
|
Common name |
Trade Name |
Chemical family |
Site of action (group) |
Commonly controlled weed(s) |
|
|
benefin |
Balon |
Dinitroaniline |
3 |
Annual grasses and broadleaf weeds |
|
|
benefin + oryzalin |
XL |
Both Dinitroaniline |
Both 3 |
Annual grasses and broadleaf weeds |
|
|
dichlobenil, |
Casoron |
Nitrile |
29 |
Nonselective preemergence control |
|
|
dimethenamid-p |
Tower |
Chloroacetamide |
15 |
Annual grasses, sedges and broadleaf weeds |
|
|
dithiopyr |
Dimension, Ultra and others |
Pyridine |
3 |
Summer annuals |
|
|
flumioxazin |
SureGuard, BroadStar and others |
N-phenylphthalimide |
14 |
Nonselective preemergence control |
|
|
indaziflam |
Marengo and Specticle |
Alkylazine |
29 |
Annual grasses, broadleaf weeds, and sedges |
|
|
isoxaben |
Gallery |
Benzamide |
29 |
Broadleaf weeds |
|
|
isoxaben + trifluralin |
Snapshot |
Benzamide + Dinitroaniline |
29 and 3 |
Broadleaf weeds and annual grasses |
|
|
napropamide |
Devrinol |
Acetamide |
15 |
Annual grasses and some broadleaf weeds |
|
|
oryzalin |
Surflan and others |
Dinitroaniline |
3 |
Annual grasses and some broadleaf weeds |
|
|
oxadiazon |
Ronstar and others |
Oxadiazole |
14 |
Annual grasses and broadleaf weeds |
|
|
pendimethalin |
Pendulum and others |
Dinitroaniline |
3 |
Annual grass and some broadleaf weeds |
|
|
prodiamine |
Barricade and others |
Dinitroaniline |
3 |
Grass and broadleaf weeds |
|
|
pronamide |
Kerb |
Benzamide |
3 |
Winter annual grassy weeds |
|
|
S-metolachlor |
Pennant Magnum |
Chloroacetamide |
15 |
Annual grasses and certain broadleaf weeds |
|
|
trifluralin |
Trifluralin |
Dinitroaniline |
3 |
Annual grasses and broadleaf weeds |