Soil-applied

DCPA (Dacthal)

Rate 4.5 to 10.5 lb ai/a (6 to 14 lb/a) depending on soil type and target weeds.

Time Apply to weed-free soil in early spring or late summer for control of susceptible winter weeds for annual weed control.

Remarks Performs erratically west of the Cascades. Sprinkler-irrigate after application to activate herbicide. Inhibits mitosis in roots and shoots.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Phthalic acid

dichlobenil (Casoron 4G)

Rate 4 to 6 lb ai/a (100 to 150 lb/a granular product)

Time Apply midwinter immediately before a cold rain to reduce volatility and enhance weed suppression.

Remarks Weigh and distribute uniformly and exactly over precisely measured areas to ensure accurate applications. Oregon results over 9 years suggest perennial weeds can be suppressed with 4-, 3-, and 2-lb ai/a rates applied in 3 consecutive years. Grazing livestock is prohibited. Inhibits cellulose and cell wall formation.

Caution Some groundcovers may not be tolerant; consult label. Pine species are sensitive to injury from Casoron 4G if applied within two years after transplanting. Do not use on trees that have been established for less than 6 months. Do not allow granules to stick to foliage or to accumulate at the soil line around the base of the tree.

Site of action Group 20: inhibits cell wall synthesis Site A

Chemical family Nitrile

dimethenamid-p (Tower 6.0 or Freehand 1.75G)

Rate 0.98 to 1.5 lb ai/a (21 to 32 oz Tower/a)

Time Apply to established plantings prior to weed emergence.

Remarks Does not control emerged weeds. Wait 2 to 4 weeks after planting for soil to settle before application. Irrigation or rainfall is needed to activate herbicide.

Caution Do not apply to seedbeds. Do not apply to sensitive ornamental plants listed on the label such as purple coneflower or ornamental grasses. Do not apply to newly transplanted ornamentals until plants have been watered and soil has been thoroughly packed and settled around roots. Use the low-labeled rate and repeat applications for extended landscape weed control. Do not apply at bud break.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Chloroacetamide

dithiopyr (Dimension 2EW, EC or 40SP and several others)

Rate 0.5 lb ai/a (2 pints/a Dimension 2EW)

Time Apply before weeds emerge around bases of ornamental plants in landscape.

Remarks For best results, prepare a weed-free surface with minimal clods and leaf debris. In the spring when buds are rapidly growing and expanding, over the top application of Dimension 2EW may temporarily injure new growth of desirable plants.

Caution Do not exceed 1.5 fl oz/1,000 sq ft every 3 to 4 months (2 pt/a), or 4.5 fl oz/1,000 sq ft per year (6 pt/a). Do not apply to plant roots or weakened ornamental plants, or when drift potential is moderate to high. Do not use in enclosed structures. Dithiopyr is toxic to fish and highly toxic to oysters, shrimp, and other aquatic organisms.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Pyridine

EPTC (Eptam 7E)

Not for use in roses

Rate 5 to 14.9 lb ai/a (5.75 to 17 pints/a) depending on target species

Time Apply and immediately incorporate 2 to 3 inches deep with a rototiller 2 weeks before transplanting balled or canned stock; or, spray postplant and incorporate with tillage. In spring, apply around established plants after growth and incorporate.

Remarks Use higher rates for perennial weed control and incorporate to a depth of 6 inches with a rototiller. Note sensitive flowers listed on label. Primarily for grass control including quackgrass suppression.

Site of action Group 8: lipid synthesis inhibitor but not an ACCase inhibitor

Chemical family Thiocarbamate

flumioxazin (SureGuard SC (51%), BroadStar G (0.25%), and others)

Rate 8 to 12 oz (0.25 to 0.38 lb ai/a) of SureGuard; 0.375 lb ai/a (150 lb/a BroadStar)

Time Apply to weed-free surface. Flumioxazin should only be applied by commercial licensed applicators. SureGuard application near ornamental plants is limited to directed sprays around well-established woody shrubs and trees. BroadStar may be applied over the top of listed species; Foliage of desirable crops must be dry at the time of application. Wet foliage will trap granules on the leaf surface or channel granules to the base of growing plants and burn the foliage

Caution Avoid sensitive crops such as buddleia (butterfly bush) and hydrangea.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family N-phenylphthalimide

halosulfuron-methyl (Sedgehammer)

Nutsedge control around established woody ornamentals in landscapes; not for use on roses or ground covers

Rate 0.031 to 0.062 lb ai/a (2/3 to 1 1/3 oz product/a)

Time After nutsedge has reached the 3- to 8-leaf stage of growth.

Remarks Wait 3 months after transplanting ornamentals, before application, and allow soil to settle around plant. A second treatment may be required 6 to 10 weeks later. Do not exceed 0.25 lb ai/a total or four applications per season. Use 0.5% nonionic surfactant concentration for broadcast applications.

Caution Do not apply as an over-the-top spray to desirable flowers, ornamentals, vegetables, shrubs or trees. Avoid contact of this product to leaves of desirable plants since foliar injury, discoloration or death may result. Apply to actively growing nutsedge that is not stressed.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Sulfonylurea

indaziflam (Specticle 20 WSP and Specticle G (0.0224 %)

Rate 0.031 to 0.062 lb ai/a (2.5 to 5 oz/a Specticle)

Time Apply in fall to early spring, prior to weed seed germination, to firmed soil that does not have cracks.

Remarks Existing vegetation must be controlled with glyphosate or burndown herbicides such as glufosinate or paraquat. Controls annual broadleaf and grass weeds, and perennial weeds from seed only. Existing perennial/biennial weeds growing from roots will not be controlled. Rainfall or irrigation of 0.25 inch or more within 3 weeks of application is required for maximum efficacy.

  • Caution Read label thoroughly to understand situations that should be avoided. This product has a long residual. Avoid direct contact with foliage, green bark, or roots of desired species. Clean spraytanks thoroughly after use. Do not apply around bedding plants.Do not apply around bearing fruit trees, unless beyond the tree drip line. Applications over heavily mulched areas may not control weeds adequately. It is best to apply the product before the mulch is applied. Avoid applications to newly seeded grasses.

Site of action Group 29: inhibits cellulose biosynthesis

Chemical family Alkylazine

isoxaben (Gallery 75 DF)

Rate 0.495 to 0.998 lb ai/a (0.66 to 1.33 lb/a)

Time Apply late summer to early fall, in early spring, or immediately after cultivation. Apply to debris-free soil surface.

Remarks Identify weeds; adjust rates according to charts on label. Activate with 0.5 inch water or shallow cultivation before weeds emerge. Chemical stability remains adequate when left on soil surface for 21 days. Primarily controls broadleaf weeds.

Caution Do not apply to newly transplanted crops until soil settles. See label for 14 sensitive ornamental species for which isoxaben is not recommended, including hydrangea, purple coneflower, and yucca. Use untreated soil to fill around transplants if isoxaben has been applied within 1 year.

Site of action Group 21: inhibits cell wall synthesis Site B

Chemical family Benzamide

napropamide (50DF)

Not for use in roses

Rate 4 to 6 lb ai/a (200 to 300 lb/a 2G)

Time Apply any time to weed-free soil, then sprinkler irrigate to wet soil 1 to 2 inches deep, or apply during midwinter rains in western Oregon for annual weed control.

Remarks Use higher rates with severe weed populations, or when broadleaf weeds are present. Primarily grass control including crabgrass and annual bluegrass. Inhibits root growth.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Acetamide

oryzalin (Surflan AS)

Rate 2 to 4 lb ai/a (2 to 4 quarts/a) depending on length of control

Time Apply any time to weed-free soil, then sprinkler irrigate with 0.5 inch if no rain falls within 1 week, or cultivate 1 inch deep to activate herbicide for annual weed control.

Remarks Consult label for tolerant ornamental species. Both grass and broadleaf control. Suppresses but will not control mustards, prickly lettuce, horseweed, and mallow. Inhibits mitosis, primarily in roots.

Caution Applications of Surflan AS over the top of plants with newly forming buds may cause injury. Use is not recommended on slender deutzia, Douglas-fir, Techny arborvitae, eastern hemlock, begonia, or coleus.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

oxadiazon (Ronstar 2G, Ronstar Flo and others)

Rate 2 to 4 lb ai/a (100 to 200 lb/a) depending on target weed species

Time Apply any time to weed-free soil and irrigate with 0.25 to 0.33 inch water immediately after applying for annual weed control.

Remarks Do not cover with soil or mulch, or incorporate, because weed control will desist. Weeds in the pink family (chickweed, mouseear chickweed, and pearlwort) are resistant. Controls a wide range of broadleaves and some grasses. Apply anytime during the year, prior to weed seed germination. Can be applied to both newly transplanted and established ornamentals. Application can be made to actively growing or dormant ornamentals. Rainfall or overhead irrigation after application will improve weed control activity.

Caution Applications of RONSTAR G must be made by a professional applicator only. Do not apply to wet foliage or under conditions in which granules will collect on leaves. For residential properties, do not allow unprotected persons or pets to enter the treated areas until the RONSTAR G Herbicide is watered-in. See label for sensitive ornamentals, including varieties of rhododendron, spruce, hemlock, azalea, viburnum, and cotoneaster. Avoid contaminating water intended for irrigation. Do not use on plants that will produce fruit within 1 year.

Site of action Group 14: protoporphyrinogen oxidase inhibitor

Chemical family Oxadiazole

pendimethalin (Pendulum 2G and 3.3EC, and others)

Rate 2 to 4 lb ai/a (100 to 200 lb/a Pendulum 2G) depending on desired length of weed control

Time Apply at time of planting or before weed seed germinates.

Remarks Controls most annual grasses and some broadleaves. Soil should be loose and free of all established weeds. Water within a few days to activate herbicide before weeds emerge.

Caution Granules may stain stone, wood, or other porous surfaces.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

prodiamine (Barricade 65WG or 4L and several others)

Rate 0.65 to 1.5 lb ai/a (1 to 2.3 lb/a 65WG) depending on desired length of weed control

Time Apply any time to weed-free soil, and incorporate with 0.5 inch water or rain within 14 days.

Remarks May be applied to newly transplanted and established ornamentals as a broadcast, over-the-top spray. Activate with 0.5 inch of rain or irrigation water, or with shallow incorporation. Inhibits germination and root development.

Caution Do not exceed 2.3 lb/a in any 12-month period.

Site of action Group 3: microtubule inhibitor

Chemical family Dinitroaniline

pronamide (Kerb SC T&O and 50 W or WP)

Not for use in roses or groundcovers

Rate 1 to 2 lb ai/a (2.5 to 5 pints/a)

Time Apply in fall before soil freezes.

Remarks Fall applications to woody ornamentals before leaf fall. Preemergence and postemergence control of susceptible winter annual and perennial grasses and chickweed. Requires soil moisture from rain or irrigation to activate; do not incorporate mechanically. Use lower rates for annual grasses and light-texture soils; higher rates for perennial grasses and heavier soils. Control of established grasses is slow. Degraded by microorganisms in warmer weather. Absorbed primarily through roots.

Caution A restricted-use pesticide for non-residential use only.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Benzamide

S-metolachlor (Pennant Magnum)

Rate 1.24 to 2.48 lb ai/a (1.3 to 2.6 pints/a)

Time Apply as direct spray toward base of desired plant, either to established ornamentals or 5 days after transplanting.

Remarks Existing weeds must be removed. Primarily controls grasses, but also some broadleaf weeds, and suppresses nutsedge. 12 month PHI if applying to fruit trees.

Caution Do not apply more than twice per year. Consult label for tolerant ornamentals.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Chloroacetamide

trifluralin (Trifluralin 10G)

Rate 0.4 lb ai/a

Time Apply before weeds emerge.

Remarks Trifluralin must be activated by a single rain or overhead sprinkler irrigation of at least 0.5 inch. If not activated within 3 days, mechanically incorporate trifluralin with equipment that won't damage. Apply before weed seeds germinate; trifluralin will not control established weeds.

Caution Do not apply to ground covers until they are established and well rooted. Do not apply Trifluralin to newly transplanted ornamentals, ground covers, flowers, and non-bearing fruit and nut crops and non-bearing vineyards until soil or potting media has been settled by packing and irrigation or rainfall and no cracks are present or injury may occur.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline