General Information

It is a violation of federal law to use this product in a manner inconsistent with its labeling.
Westar Herbicide must be used only in accordance with instructions on this label, or in separately published Bayer CropScience LP instructions.

Bayer CropScience LP will not be responsible for losses or damages resulting from the use of this product in any manner not specifically instructed by the label. User assumes all risks associated with such non-labeled use.

Do not apply more than 6.0 ounces (0.375 pounds active) active ingredient sulfometuron methyl per acre per year when using this product or any other product containing sulfometuron methyl.

Do not apply more than 3.18 ounces active ingredient (0.199 pounds active) sulfometuron methyl per acre per single application to an Agricultural site when using this product alone or in combination with any other product containing sulfometuron methyl.

Do not apply more than 4.5 ounces active ingredient (0.281 pounds active) sulfometuron methyl per acre per single application to a Non-Agricultural site when using this product alone or in combination with any other product containing sulfometuron methyl.

Westar Herbicide contains hexazinone. When applied alone or in combination with other products containing hexazinone: (1) For forestry use, do not apply more than 5 pounds of active ingredient per acre per year (2) For noncrop use, do not apply more than 8 pounds of active ingredient per acre per year.

Do not use on food or feed crops.

Do not apply this product in a way that will contact workers or other persons, either directly or through drift. Only protected handlers may be in the area during application. For any requirements specific to your state or tribe, consult the agency responsible for pesticide regulation.

The correct use rates by crop and geographical area, specified on the label, and proper mixing/loading site considerations and application procedures must be followed to minimize potential for hexazinone movement into ground water. Users are encouraged to consult with their state Department of Agriculture, Extension Service, or other pesticide lead agency for information regarding soil permeability, aquifer vulnerability, and best management practices for their area.

Westar Herbicide is a dispersible granule that is mixed in water and applied as a spray. Westar Herbicide may be used for weed control in terrestrial non-crop sites and for the control of certain weeds in conifers grown for forestry and Christmas tree production.

Westar Herbicide is an effective herbicide providing both contact and residual control of many annual and perennial weeds.

Westar Herbicide can be tank mixed with other herbicides registered for use in forestry, Christmas tree and non-crop sites. Read and follow the Directions for Use for both products.

Westar Herbicide is non-corrosive to spray or mixing equipment, non-flammable and non-volatile.

Precaution must be exercised when applying Westar Herbicide near desirable trees or shrubs as they can absorb Westar Herbicide through roots extending into treated areas.

This product may be applied on forestry, Christmas tree and non-crop sites that contain areas of temporary surface water caused by collection of water between planting beds, in equipment ruts, or in other depressions created by management activities. It is permissable to treat intermittently flooded low lying areas, seasonally dry flood plains and transitional areas between upland and lowland sites when no water is present. It is also permissible to treat marshes, swamps and bogs after water has receded, as in seasonally dry flood deltas.

A drift control agent may be used at the manufacturer's listed rate in the application of WESTAR HERBICIDE.

Westar Herbicide is absorbed through roots and foliage. Once absorbed, Westar Herbicide controls susceptible weeds by two different mechanisms. The sulfometuron methyl component inhibits the biosynthesis of the essential amino acids valine and isoleucine. The hexazinone component inhibits photosynthesis. Several factors influence the effectiveness and duration of weed control, including use rates, weed spectrum and size, degree of weed infestation, soil pH and organic matter content, precipitation, and growing conditions during and following herbicide treatment.

Moisture is required to activate Westar Herbicide in the soil. Best results are obtained when the soil is moist at the time of application and 1/4 to 1/2 inch of rainfall occurs within 2 weeks after application.

For best results, apply Westar Herbicide preemergence or early postemergence when weeds are less than 2 inches in height or diameter. Herbicidal activity is most effective under conditions of high temperature (above 80 °F), high humidity, and good soil moisture. Herbicidal activity may be reduced when vegetation is dormant, semi-dormant, or under stress(e.g. temperature or moisture).

Herbicidal activity will usually appear within 2 weeks after application to susceptible weeds under warm, humid conditions; while 4–6 weeks may be required when weather is cool or dry, or when susceptible weeds are under stress. If rainfall after application is inadequate to activate Westar Herbicide in the soil, weeds may recover from contact effects and continue to grow.

This product may be considered for use on public, private, and tribal lands to treat certain weed species infestations that have been determined to be invasive, consistent with the Federal Interagency Committee for the Management of Noxious and Exotic Weeds (FICMNEW) National Early Detection and Rapid Response (EDRR) System for invasive plants. Effective EDRR systems address invasions by eradicating the invader where possible, and controlling them when the invasive species is too established to be feasibly eradicated. Once an EDRR assessment has been completed and action is recommended, a Rapid Response needs to be taken to quickly contain, deny reproduction, and if possible eliminate the invader. Consult your appropriate state extension service, forest service, or regional multidisciplinary invasive species management coordination team to determine the appropriate Rapid Response provisions and allowed treatments in your area.

When herbicides that affect the same biological site of action are used repeatedly over several years to control the same weed species in the same field, naturally-occurring resistant biotypes may survive a correctly applied herbicide treatment, propagate, and become dominant in that field. Adequate control of these resistant weed biotypes cannot be expected. If weed control is unsatisfactory, it may be necessary to retreat the problem area using a product affecting a different site of action.

To better manage herbicide resistance through delaying the proliferation and possible dominance of herbicide resistant weed biotypes, it may be necessary to change cultural practices within and between crop seasons such as using a combination of tillage, retreatment, tank-mix partners and/or sequential herbicide applications that have a different site of action. Weed escapes that are allowed to go to seed will promote the spread of resistant biotypes.

It is advisable to keep accurate records of pesticides applied to individual fields to help obtain information on the spread and dispersal of resistant biotypes. Consult your agricultural dealer, consultant, applicator, and/or appropriate state agricultural extension service representative for specific alternative cultural practices or herbicide recommendations available in your area.

This product may be used as part of an Integrated Pest Management (IPM) program that can include biological, cultural, and genetic practices aimed at preventing economic pest damage. IPM principles and practices include field scouting or other detection methods, correct target pest identification, population monitoring, and treating when target pest populations reach locally determined action thresholds. Consult your state cooperative extension service, professional consultants or other qualified authorities to determine appropriate action treatment threshold levels for treating specific pest/crop systems in your area.

Understanding the risks associated with the application of Westar Herbicide is essential to aid in preventing off-site injury to desirable vegetation and agricultural crops. The risk of off-site movement both during and after application may be affected by a number of site specific factors such as the nature, texture and stability of the soil, the intensity and direction of prevailing winds, vegetative cover, site slope, rainfall, drainage patterns, and other local physical and environmental conditions. A careful evaluation of the potential for off-site movement from the intended application site, including movement of treated soil by wind or water erosion, must be made prior to using Westar Herbicide. This evaluation is particularly critical where desirable vegetation or crops are grown on neighboring land for which the use of Westar Herbicide is not labeled. If prevailing local conditions may be expected to result in off-site movement and cause damage to neighboring desirable vegetation or agricultural crops, do not apply Westar Herbicide.

Before applying Westar Herbicide the user must read and understand all label directions, precautions and restrictions completely, including these requirements for a site specific evaluation. If you do not understand any of the instructions or precautions on the label, or are unable to make a site specific evaluation yourself, consult your local agricultural dealer, cooperative extension service, land managers, professional consultants, or other qualified authorities familiar with the area to be treated. If you still have questions regarding the need for site specific considerations, please call 1-800-331-2867.

- Do not apply this product through any type of irrigation system.
- Do not use in nurseries, seed beds or ornamental plantings.
- Poor weed control may occur when applications are made to saturated soil and rain occurs within 24 hours.
- Do not drain or flush equipment on or near desirable trees or other plants, or on areas where their roots may extend, or in locations where the chemical may be washed or moved into contact with their roots as injury or loss of desirable trees and other plants may result.
- Applications made where runoff water flows onto agricultural land may injure crops. Applications made during periods of intense rainfall, to soils saturated with water, surfaces paved with material such as asphalt or concrete, or soils through which rainfall will not readily penetrate may result in runoff and movement.
- Leave treated soil undisturbed to reduce the potential for Westar Herbicide movement by soil erosion due to wind or water.
- Do not apply when the soil is frozen or covered with snow or standing water.
- Treatment of powdery, dry soil or light, sandy soil when there is little likelihood of rainfall soon after treatment may result in off target movement and possible damage to susceptible crops when soil particles are moved by wind or water. Injury to crops may result if treated soil is washed, blown, or moved onto land used to produce crops. Exposure to Westar Herbicide may injure or kill most crops. Injury may be more severe when the crops are irrigated. Do not apply Westar Herbicide when these conditions are identified and powdery, dry soil or light or sandy soil are known to be prevalent in the area to be treated.
- Applications may not be made to soil that is subject to wind erosion when less than a 60% chance of rainfall is predicted to occur in the treatment area within 48 hours. Soils that are subject to wind erosion usually have a high silt and/or fine to very fine sand fractions. Soils with low organic matter also tend to be prone to wind erosion.
- Do not use Westar Herbicide on lawns, driveways, tennis courts, or residential or recreational areas.
- If the treated site is to be converted to an agricultural (food, feed or fiber) or horticultural crop, do not plant the treated site(s) for at least one year after the Westar Herbicide application. A field bioassay must then be completed before planting to crop. To conduct a field bioassay, grow to maturity test strips of the crop you plan to grow the following year. The test strips should cross the entire field including knolls and low areas. Crop response to the bioassay will indicate whether or not to plant the crop grown in the test strips. In the case of suspected off-site movement of Westar Herbicide to crop-land, in addition to conducting the above described bioassay, soil samples should be taken and quantitatively analyzed by an analytical laboratory for Westar Herbicide or any other herbicide which could have an adverse effect on the crop.
- Do not use this product in the following counties of Colorado: Saguache, Rio Grande, Alamosa, Costilla and Conejos.
- Do not apply in or on irrigation ditches or canals including their outer banks.
- If tank mixing this product with other pesticides, follow the directions for determining compatibility with tank mix partners prior to tank mixing them. Follow instructions for determining compatibility given under MIXING WITH OTHER HERBICIDES in the SPRAY PREPARATION section of this label.

Limitations, Restrictions, and Exceptions


WESTAR herbicide is a dispersible granule that is mixed in water and applied as a spray for weed control in conifers grown for Christmas tree production.


WESTAR is labeled for weed control in plantings. Other species of conifers grown for Christmas tree production may be treated providing the user has prior experience indicating acceptable tolerance to WESTAR. Without prior use experience, treat a small area with WESTAR to determine tolerance of specific conifer species before large-scale treatments are made as unacceptable injury to any conifer species not listed on the label may occur.

To help ensure safety to Grand Fir, use large transplant stock and apply DuPont WESTAR at 1.0 to 1.25 pounds per acre, or use after trees have been established for at least one growing season.

WESTAR herbicide may be applied by ground equipment and where appropriate, aerial equipment (helicopter only). For best results, apply either preemergence to weeds or early postemergence when weeds are small and actively growing.

WESTAR may be used on other conifer species where adequate conifer tolerance has been determined. For best conifer safety on sites with varying soil textures, use rates based on the soil type with the coarsest texture.


For broadcast treatments, apply only when trees are dormant. Applications where the spray comes into direct contact with conifers after dormancy break in the spring or before the final resting bud has hardened in the fall may severely injure or kill the trees. If trees have broken dormancy, treatments should be made using a directed application to prevent the spray from coming in contact with new growth foliage.

For new plantings, delay application until rainfall has settled the soil around the base and root system of seedling transplants.


Low rates of WESTAR can kill or severely injure most crops. Following a WESTAR application, the use of spray equipment to apply other pesticides to crops on which WESTAR or its active ingredients are not registered may result in their damage. The most effective way to reduce this crop damage potential is to use dedicated mixing and application equipment. Alternatively, carefully follow the “Sprayer Clean Up” directions on the label.


Apply WESTAR as a broadcast or directed spray. Select a spray volume and delivery system that provides a uniform spray pattern to help ensure thorough coverage. Be sure the sprayer is calibrated before use. Avoid overlapping treated areas and shut off spray booms while starting, turning, slowing, or stopping to avoid injury to conifers.

WESTAR applications made with backpack or boomless nozzle spray equipment may cause severe injury to conifers and/or poor weed control performance due to the inherent variability (rate and coverage) in the uniformity of application.

Air (Helicopter Only)

Aerial application of WESTAR is permitted where Christmas Trees are grown in a forestry-like setting. Where Christmas Trees are grown in close proximity to other crops, other desirable species, or residential areas, take extreme precautions to avoid drift or apply by ground. Avoiding spray drift is the responsibility of the applicator.


Brackenfern, Fescue, Raspberry: Suppression - a visual reduction in plant population and/or plant vigor as compared to an untreated area and generally not accepted as control.

Catsear, smooth, Catsear, spotted, Ryegrass, Italian: Additional weeds suppressed at 1 pound per acre.


- Do not apply with air-blast spray equipment.

- Do not use WESTAR in Christmas tree seed beds or transplant nurseries.

- Do not apply WESTAR within 14 days before or after an organophosphate insecticide (such as, chlorpyrifos) application as injury to conifers may occur.

- On tracts of land where various soil types occur and rate selection is difficult, Christmas tree damage or reduced weed control may occur due to the different rates required for various soil types.

- Poor weed control may occur when applications are made to soils already saturated and rain occurs while soils are still saturated.

- Christmas tree injury may occur when WESTAR is used on trees that are suffering from loss of vigor caused by insects, diseases, drought, winter damage, animal damage, excessive soil moisture, planting shock, poor planting conditions, over or under fertilization, previous agricultural practices or other stresses. Injury may also occur to Christmas trees growing on gravelly or rocky soils.

- Injury to Christmas trees may occur where drought or poor planting conditions cause the soil to crack and expose roots to air.

- Grand Fir seedlings may be injured (poor color or increased mortality) if transplant stock is small or use rate of WESTAR is higher than 1.25 pound per acre.

- The use of a surfactant in applications made over-the-top of non-dormant Christmas trees is not advised. If a surfactant is used with WESTAR, allowing the spray to contact Christmas tree foliage may injure or kill the trees. The user assumes all responsibility for Christmas tree injury if a surfactant is used with WESTAR applied after planting.

Restricted Entry Interval

48 hours