W244 Common Herbicides for Ornamental Weed Control Greg Armel, Extension Horticultural Weed Specialist Beth Babbit, Extension Urban Horticulture Area Specialist

This chart provides recommendations for the best treatments available for weed control in most ornamental plants. The rates and recommendations for these herbicides are specific for ornamental plants and the chart should be used in accordance with the label. Herbicides listed in this chart are common and often easy for consumers to find; there are many other acceptable herbicides on the market that may suit a similar purpose. Always consult the label before applying any pesticide on a specific ornamental plant or variety.

Products applied for burndown of existing vegetation prior to planting and/or post-directed for weed control around existing ornamental plants. Extreme care should be taken to avoid spray contact on the foliage of desired vegetation. • Preemergence and/or pre-plant applied herbicides for residual control of weeds in selected ornamental plants. • Postemergence selective weed control in specific ornamental plants. • Products applied for burndown of existing vegetation prior to planting and/or post-directed for weed control around existing ornamental plants in organic production systems. Extreme care should be taken to avoid spray contact on the foliage of desired vegetation. •

1 • Chemical Ornamentals appearing on label Weeds controlled Timing of Application Application Rates

Burndown

Glyphosate Many plants, see label for specifics A non-selective herbicide Pre-plant applications 1 to 5 pints/acre or Trade name: Roundup®, that controls many allowed in most plants. 1 to 10% solutions other weeds. Post-directed and spot depending on the crop spray treatments are allowed for certain Surfactant requirements ornamentals as long as are based upon care is taken to avoid formulation of contact with any foliage or glyphosate selected. green tissue. Consult label Please consult product labels for more label for specific specific information. recommendations.

Glyphosate has no soil residual activity.

Pelargonic acid All landscape trees, bedding plants, A non-selective herbicide Post-directed (avoiding 3 to 10% solution (spot Trade name: Scythe®, other flowers and other ornamentals that controls many spray on foliage or spray): weeds. green bark) and pre- plant applications in all 3-5%- solution for landscape trees, bedding annual weeds plants, flowers and other 5-7%- solution for ornamentals. perennial weeds 8-10%- solution for Pelargonic acid has no soil maximum burndown of residual activity. mature weeds

No additional adjuvant required.

Diquat dibromide Around all types of ornamental plants in A non-selective Post-directed (avoiding 0.75 fl oz plus labeled Trade name: Reward®, gardens and landscapes. herbicide that controls spray on foliage or rate of a 75% active other many weeds; however, green bark) and pre- nonionic surfactant in broadleaf weeds are plant applications in all 1 gallon of water (spot more susceptible than landscape trees, bedding spray) grass species. In general, plants, flowers and other grasses are most ornamentals. susceptible when 1 inch or less in height. Diquat dibromide has no soil residual activity.

2 Glufosinate For use around trees and shrubs in Broadleaf weeds: Post-directed (avoiding 2 to 6 quarts/acre Trade name: Finale®, other residential gardens and landscapes. annual sowthistle, spray on foliage or green broadcast or 2 to 4 fl oz bindweed, buffalobur, bark) around trees and per 1 gallon of water for burdock, Canada thistle shrubs. spot spray applications (suppression), curly dock, dandelion, fleabane, Glufosinate has no soil goldenrod, hemp residual activity. dogbane (suppression), horsetail, lambsquarters, mugwort (suppression), musk thistle, nettle, nightshade, redroot pigweed, plantain, prickly lettuce, ragweed, mustard species, velvetleaf, Virginia copperleaf, white heath aster, wild buckwheat, wild onion, woodsorrel and others

Grasses: Annual bluegrass, bermudagrass (suppression), crabgrass, dallisgrass, fescue, Kentucky bluegrass, ryegrass, sandbur and others

3 Preemergence and/or Pre-plant

Trifluralin For use on several established Several annual grasses, Preemergence weed 1 oz / 10 sq ft Trade name: Preen™ ornamental plantings. carpetweed, chickweed, control when applied to Garden Weed Preventer, Florida pusley, goosefoot, established ornamental other henbit, knotweed, plants before weeds lambsquarters, pigweed have emerged. This spp. and purslane. product needs immediate incorporation after application with irrigation, rainfall or light tillage.

Orzyalin For use on several field and container- Several annual grasses, Preemergence weed 2 to 4 quarts/acre or 1.5 Trade name: Surflan® AS grown ornamentals. Injury has been bittercress, carpetweed, control when applied to to 3 fluid oz/1000 sq ft reported on the following species: chickweed, filaree, established ornamental slender deutzia, Douglas fir, Techny groundsel, henbit, plants before weeds arborvitae, eastern hemlock, begonia and knotweed (prostrate), have emerged. This coleus lambsquarters, pigweed product performs better spp., puncturevine, with incorporation after purslane, shepherd’s application with irrigation, purse, spurge (prostrate) rainfall or light tillage. and yellow woodsorrel.

DCPA Use on more than 120 different Several annual grasses, Pre-plant or preemergence 1 pint in 3 to 7 gallon Trade name: Dacthal®, ornamental plants. Do not use on lambsquarters, weed control treats 3000 sq ft other Dichondra, bugleweed, button pink, carpetweed, chickweed, carnation, geum, germander, ice plant, purslane, field pansy pansy, phlox, Sweet William, Telanthera. and suppression of other Consult label for specific details. broadleaf weeds.

4 Postemergence Selective Weed Control

Sethoxydim Several bedding plants, groundcovers, Provides selective Provides selective 2.25 pints/acre or 0.8 Trade name: Segment, shrubs, trees and wildflowers. postemergence postemergence contact fluid oz / 1000 square other contact control of grass control only. feet on grasses up to 6 several grass species, inches in height including, but not limited Sethoxydim has little to no to, bermudagrass, soil residual activity. 3.75 pints/acre or 1.4 broadleaf signalgrass, fluid oz / 1000 square crabgrass spp., foxtail feet on grasses 6 to12 spp., goosegrass and inches in height johnsongrass. No additional adjuvant required.

Fluazifop-p-butyl Several ornamental plants. Warning: Provides selective Provides selective 64-96 fluid oz/acre Trade name: Ornamec®, Post-directed applications may be safest postemergence contact postemergence contact plus 0.25% nonionic other for certain ornamental plants. Consult control of several grass grass control only. surfactant label. species including, but not limited to, bermudagrass, Fluazifop-p-butyl has little Spot spray: 2.5 fl oz/gal broadleaf signalgrass, to no soil residual activity. plus surfactant crabgrass spp., foxtail spp., goosegrass and johnsongrass.

Clethodim Several ornamental trees, groundcovers, Provides selective Provides selective 16-32 fl oz/acre or Trade name: Envoy Plus™, garden flowers and plants and shrubs. postemergence contact postemergence contact 0.4-0.8 fl oz/1000 sq other control of several grass grass control only. ft plus 0.25% nonionic species including but not surfactant limited to bermudagrass, Clethodim has little to no broadleaf signalgrass, soil residual activity. Spot spray: 1/2 to 1% crabgrass spp. foxtail (0.65 to 1.3 fl oz/gal) plus spp. and johnsongrass. surfactant Does not always adequately control goosegrass.

Halosulfuron Apply in landscaped areas with Certain broadleaf weeds, Use as a spot spray 0.9 grams in 1 to 2 Trade name: established woody ornamentals. Do yellow and purple around established woody gallons of water will treat Sedgehammer™, other not apply over-the-top of flowers, nutsedge and kyllinga ornamentals. 1000 sq ft ornamentals, shrubs or trees. spp. Add 1/3 oz of nonionic surfactant per gallon of water

5 Bentazon Liriope (common, green), Ajuga, Provides selective Provides selective 1 to 2 pints/acre or 0.375 Trade name: Basagran® Boxwood ‘Winter Gem’, Holly (‘Bufordii,’ postemergence contact postemergence contact to 0.75 fl oz/1000 sq ft T/O, other ’Compacta,’ ‘Dwarf Burford’), Impatiens control of certain broadleaf and sedge ‘Balsam,’ English Ivy, Marigold broadleaf weeds such control. Spot spray: 0.75 fl oz per ‘Aurora Gold,’ Mugo pine, Red oak, as ballonvine, coffee 1 to 2 gallons of water Pachysandra, Ornamental cabbage senna, galinsoga, pansy, Ornamental cabbage ‘Colorup,’ groundsel, ladysthumb, A non-phytotoxic oil Petunia (‘Madness Plum,’ ‘Ultra white’), lambsquarters, mustard, concentrate may be Snapdragon ‘L. Scarlet,’ and Yew Pennsylvania smartweed, added at 0.75 fluid oz / (Japanese ‘Densiformis,’ ‘Hatfieldii’ and prickly sida, purslane, 1000 sq ft (2 pints/acre). ‘Hicks’) ragweed (common, giant), redweed, sesbania, shepherd’s purse, spurred anoda, lawn burweed, wild buckwheat, wild poinsettia, wild sunflower and yellow nutsedge.

Bentazon has no soil residual activity.

Imazaquin Indian hawthorne, Dwarf yaupon holly, Provides selective Apply postemergence to Apply 0.2 to 0.26 Trade name: Image®, other Blue Pfitzer Juniper, Helleri holly, Red control of black medic, established landscape oz / 1000 sq ft as a tip photinia, Yucca, Wax Myrtle, Burford buttercup, Carolina ornamentals for selective broadcast application. Holly, Gardenia, ‘Miami Supreme,’ ‘Flame geranium, carpetweed, contact and residual weed of the Woods,’ Confederate jasmine, common chickweed, control. Spot spray: dissolve 0.5 Parsons Juniper, Blue pacific juniper, cutleaf eveningprimrose, oz in 3 gallons of water Blue rug juniper, Red crape myrtle, eclipta, field sandbur, Asiatic jasmine, Giant liriope, Variegated green kyllinga, hairy Add 0.25% v/v liriope, Mondo grass, Pachysandra, bittercress, henbit, nonionic surfactant Hosta ‘Lancifolia,’ Society garlic. knawel, mouseear for postemergence chickweed, perennial applications. * Do not apply to food-producing vines, ryegrass, pigweed trees or berries; vegetable gardens; species, purple container ornamentals; nursery liners; deadnettle, purple seedlings; or tree nurseries. nutsedge, red sorrel, white clover, wild garlic, wild onion and yellow nutsedge

6 Organic Burndown*

Vinegar - active ingredient: All ornamental plants Certain broadleaf weeds Organic post-directed At least a 20% solution acetic acid with grass suppression (avoiding spray on for the most consistent foliage or green bark of performance ornamental plants) contact control. Multiple applications are often needed for long- Vinegar has no soil term control. residual activity.

Boiling water All ornamental plants Many weeds Organic post-directed Pour until plant foliage (~212° F) (avoiding contacting becomes wilted. foliage or green bark of ornamental plants). Multiple applications are often needed for long- term control.

Flame/ torch All ornamental plants Many broadleaf weeds Organic post-directed Flame applications will with some grass (avoiding contacting require approximately suppression; broadleaf foliage or green bark of 5 to 15 gallons/ weeds that are larger ornamental plants). propane per acre. or have a waxy cuticle Use with caution in (i.e., purslane) will not be Some heat stress may accordance with local controlled adequately. be noted on ornamental fire regulations. plants even if vegetation does not come in direct contact with the flame.

* Organic weed control products listed here can cause human harm such as chemical- or heat-related burns, if used improperly.

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