Controlling Weeds in Nursery and Landscape Plantings

Rate of absorption: Allow 1 hour between application and rainfall.

Mode of action: Absorbed through leaves and translocated to growing points above and below ground, where it stops growth, resulting in death of the plant.

Crop uses: Established turfgrass; ornamental trees and shrubs; herbaceous and flowering plants.

Weed control strengths: Postemergence control of most annual and a few perennial grasses.

Weed control weaknesses: Does not control broadleaf weeds, sedges, or some perennial grasses.

Notes: May be used over the top of many ornamentals. The addition of a surfactant will improve coverage of treated foliage. Do not use Acclaim Extra on Bar Harbor juniper, salvia, podocarpus, or pittosporum.

Rate of absorption: Allow 8 hours between application and irrigation or rainfall.

Mode of action: Effective mainly through contact action, so weeds must be thoroughly covered with spray solution.

Crop uses: Apply as a directed spray to nonbearing fruit and nut trees, turf, and selected field-grown ornamental trees, shrubs, and ground covers. Over-the-top applications can be made on English ivy, liriope, and pachysandra.

Weed control strengths: Controls annual sedges, yellow nutsedge, and some other broadleaved weeds. It suppresses Canada thistle.

Weed control weaknesses: Does not control grasses or many broadleaved weeds.

Notes: Avoid contact with crop foliage, especially conifers. The oil concentrate may cause a slight burn of ornamentals, but new growth following application should be normal, and vigor is not reduced. Injury to ornamentals is more likely to occur under hot, humid conditions.

Mode of action: Penetrates cuticle and results in plant desiccation.

Crop uses: Use inside greenhouses on growing containers, benches, patios, tree trunks, and lawns.

Weed control strengths: Postemergence control of mosses, algae, lichens, and liverworts.

Weed control weaknesses: Do not use for general weed control.

Notes: Prevent overspray or runoff from contacting plant foliage. Treated surfaces may be temporarily slippery. Do not apply to moss or algae in lawns or turf when air temperature exceeds 85 degrees F; do not use on fruit trees.

Rate of absorption: Do not apply if rainfall is expected within 1 hour of application.

Mode of action: Absorbed through leaves and translocated to growing points above and below ground, where it stops growth, resulting in the death of the plant.

Crop uses: Ornamental trees, shrubs, ground covers, and vines; garden flowers; nonbearing fruit trees; and greenhouses.

Weed control strengths: Controls most annual and perennial grasses.

Weed control weaknesses: Does not control sedges, broadleaved weeds, or fine fescues (red, chewings, hard, sheeps).

Notes: 7 to 14 days are required for control of grasses.

Rate of absorption: Allow 4 hours between application and rainfall.

Mode of action: Absorbed into the leaves, but there is little translocation. Kills primarily through contact activity, so thorough coverage of the foliage is necessary.

Crop uses: Landscape, field, and container-grown established woody ornamentals. One of the few herbicides labeled for use in greenhouses, even with plants present.

Weed control strengths: It is a nonselective herbicide that controls a broad spectrum of emerged annual and perennial grasses, broadleaved weeds, and sedges.

Weed control weaknesses: As a contact herbicide, it does not control the underground portions of perennial weeds.

Notes: Avoid all contact with foliage or green tissue of desirable vegetation. The bark of thin-barked trees can be injured if directly sprayed. Do not use to control suckers. When used in greenhouses, air circulation fans must be turned off, and large droplet, low-pressure type nozzles should be used.

Rate of absorption: Allow 1 hour between application and rainfall.

Mode of action: Absorbed through leaves and translocated to growing points above and below ground, where it stops growth, resulting in the death of the plant.

Crop uses: Landscape, field, and container-grown woody ornamentals; ground covers; flowers; and Christmas trees. Can be used in greenhouses.

Weed control strengths: Postemergence control of annual and perennial grasses.

Weed control weaknesses: Does not control broadleaved weeds, sedges, rushes, lilies, and other nongrasses. Bluegrass has shown considerable tolerance. Does not control fine fescues (red, chewings, hard, and sheeps).

Notes: Make applications to grasses 2 to 8 inches tall, but before tillering or heading. May be applied over the top of many ornamentals, but a directed spray is specified for some. Injury symptoms of treated grasses develop slowly (7 to 14 days). Do not tank mix with other pesticides or fertilizers.

Rate of absorption: Allow 4 hours between application and rainfall.

Mode of action: An auxin-type herbicide that is believed to act similar to 2,4-D.

Crop uses: Christmas tree plantings-site preparation prior to planting and directed spray applications after planting; around buildings and in noncrop areas.

Weed control strengths: Postemergence directed spray for hard to control herbaceous annual and perennial broadleaved weeds and woody species such as poison ivy. Is the best nonresidual, postemergence herbicide for controlling woody species.

Weed control weaknesses: Does not control grasses or sedges.

Notes: Apply only in well-established plantations planted at least one full year before application; do not apply when conifers are actively growing. Injury potential is greatest to white pine and Douglas fir. To control unwanted woody species, mix a 10% solution of Garlon 4 in oil (diesel or an oil especially formulated for 'basal bark' applications) and apply to the lower 12 to 18 inches of the woody plants in the dormant season.

Solubility: at pH 5, 15 ppm (low); at pH 7, 1630 ppm (high).

Stability on soil: High; very low photodegradation or volatilization. Subject to hydrolysis in moist soils. Medium to low leaching potential, depending on soil pH.

Mode of action: Absorbed by roots and germinating plant shoots; inhibits synthesis of amino acids.

Crop uses: Used as a directed spray around established woody ornamentals.

Weed control strengths: Controls yellow nutsedge and horsetail (Equisetum).

Weed control weaknesses: It is labeled for nutsedges and horsetail only.

Notes: Used at extremely low rates-measure carefully. Use 0.5% nonionic surfactant with Manage (1 qt/50 gal; 2 tsp/gal).

Rate of absorption: Allow 1 to 2 hours between application and rainfall.

Mode of action: Contact. Rapidly absorbed by green tissue and interacts with light to produce superoxides which destroy plant cells.

Crop uses: Preplant cleanup for conventional planting and postemergence directed spray in orchards, vineyards, and ornamentals and beneath greenhouse benches. Can be used in industrial, recreational, golf course, commercial, residential, and public areas. Aquatic uses include edges of ponds, lakes, and ditches that have little outflow and are totally under the control of the user.

Weed control strengths: A nonselective postemergence contact herbicide used to control most small annual broadleaved and grassy weeds and to suppress perennial weeds in production nurseries.

Weed control weaknesses: Does not kill below-ground parts of perennial weeds. Some annuals listed on the label are considered difficult to kill.

Notes: Reward kills through contact activity, so thorough coverage of the weed foliage is necessary. Do not allow spray to contact thin bark or green stems of woody ornamentals.

Rate of absorption: Allow 6 hours between application and rainfall.

Mode of action: Absorbed through foliage and green stems and translocated throughout the plant in association with carbohydrates. Since carbohydrate movement is upward during the early stages of regrowth of perennial weeds, best control of perennial weeds is achieved if application is made near the time of flowering, when carbohydrate movement is downward into roots and rhizomes. Interferes with growth, often resulting in death of the plant.

Crop uses: Roundup Pro and Roundup Ultra are used in noncropland, preplant weed cleanup, postplant directed spray in many established woody plants and perennial crops including Christmas trees. Rodeo and Accord can control weeds in or around waterways, including irrigation ponds.

Weed control strengths: Broad spectrum, postemergence control of most herbaceous and woody plants.

Weed control weaknesses: Few.

Notes: Avoid contact with foliage and thin-barked or green stems of desired crops because severe injury or death may result. Bark splitting may occur 1 to 2 years after improper application(s). Foliar injury may be expressed for as long as 5 years after a treatment. Do not use more than 25 gallon spray solution per acre. Do not use to control suckers. Use a surfactant that has an aquatic label with Accord or Rodeo for aquatic weed control.

Mode of action: A contact herbicide that disrupts cell membranes, causing rapid cell desiccation. Thorough coverage of weed foliage is necessary to obtain control.

Crop uses: In and around walks, driveways, flower beds, trees, and shrubs. One of the few materials labeled for use in greenhouses.

Weed control strengths: Postemergence contact herbicide for control of most young, succulent, actively growing weeds.

Weed control weaknesses: Does not control mature or woody weeds; older annual and perennial weeds may only be suppressed.

Notes: Do not apply using hose-end sprayers. Keep people and pets off treated areas until dry to avoid transfer to desirable vegetation; avoid contact with eyes and skin as irritation can occur. Its odor in enclosed areas is objectionable.

Rate of absorption: Allow at least 6 hours between application and rainfall.

Mode of action: Absorbed through leaves and translocated to growing points, where it has auxin hormone herbicide-type activity.

Crop uses: Christmas trees and conifer nurseries for the following species: balsam, fraser, noble, grand, and Douglas fir; blue spruce, Scotch pine, and white pine.

Weed control strengths: Selective postemergence control of certain broadleaf weeds, especially those in the legume (clover, crownvetch) and composite (Canada thistle) families.

Weed control weaknesses: Does not control grasses, sedges, or many broadleaved weeds such as lambsquarter and pigweed.

Notes: Apply before weeds are fully developed. Do not use a surfactant or tree injury may occur.

Rate of absorption: Allow 6 hours between application and rainfall.

Mode of action: Absorbed by foliage and translocated to above and below ground growing points.

Crop uses: Conifer seedling establishment, nursery beds, and Christmas tree plantings; noncrop areas and nonbearing orchards or vineyards to within 1 year of harvest.

Weed control strengths: Nonselective systemic postemergence control of most annual and perennial grasses and broadleaved weeds.

Weed control weaknesses: Control of weeds in excess of 6 inches in height may be reduced, except for bermudagrass and johnsongrass, which should be allowed to reach the seedhead stage before application.

Notes: Avoid contact with foliage and thin bark, or green stems of desirable plants.

Rate of absorption: Allow 1 hour between application and rainfall.

Mode of action: Absorbed through leaves and translocated to growing points above and below ground, where it stops growth, resulting in the death of the plant.

Crop uses: Field and container-grown woody ornamentals, ground covers, flowers, and Christmas trees.

Weed control strengths: Postemergence control of annual and perennial grasses.

Weed control weaknesses: Does not control broadleaved weeds, sedges, annual bluegrass, or fine fescues (red, chewings, hard, and sheep).

Notes: May be applied over the top of many ornamentals. Injury symptoms on treated grasses develop slowly (7 to 14 days). Can be used for growth suppression of tall fescue used as a cover crop.