close up of a strawberry crop
product name - Poast Ultra herbicide

Poast Ultra

Group 1


Poast® Ultra is the benchmark for safe, reliable and effective annual grass control.

  •  Choose Poast Ultra for your post emergent grass control in soybeans and dry beans.
  •  Also registered for 50 other crops.

Labels & SDS


Labels & SDS

Additional Resources



Benefits of Poast Ultra

  • Poast Ultra is a contact and systemic herbicide.
  • Uptake is primarily through its leaves.
  • Depending on growing conditions and crop competition, the time required for complete control is 7 to 21 days following treatment.
  • Translocated through the quackgrass plant to the rhizomes and kills actively growing rhizome buds and above ground vegetation.
  • Dormant rhizome buds will remain unaffected and regrowth can occur from these buds.
  • Applied according to label directions, re-growth of the quackgrass will not be significant until 6 to 8 weeks after treatment, depending on growing conditions, crop cultivation practices and crop competition.

Product Info & Application Guide

Weeds Controlled

Poast Ultra will control the following grasses:

  • Barnyard grass
  • Crabgrass, large
  • Fall panicum
  • Foxtail barley (suppression only)
  • Foxtail, green
  • Foxtail, yellow
  • Persian darnel
  • Proso millet
  • Quackgrass
  • Volunteer barley
  • Volunteer corn
  • Volunteer wheat
  •  Wild oats
  • Witchgrass


Poast Ultra is labeled for use on 50 crops, including soybeans

When to Apply

  • Poast Ultra can be applied when annual grasses are between 1 to 6-leaf stage.
  • For the most effective control of annual grasses, apply when weeds are in the 2 to 5-leaf stage, when plants are small and actively growing, soil moisture is good and the crop is small enough to permit thorough spray coverage.
  • Most effective at controlling wild oats and volunteer cereals if applied before tillering.
  • For quackgrass control, apply when the plant is actively growing, up to the 3-leaf stage (8 to 12 cm in height).
  • Use only on cultivated land where preplant tillage operations have been carried out to break up quackgrass roots.
  • Where quackgrass is well established, thorough preplant cultivation to a depth of 10 cm is recommended to break up roots and provide uniform grass emergence for improved control.
  • Apply for suppression of foxtail barley before the weed has tillered.

How Much to Apply

  • Each case contains two 7.7 L containers of Poast Ultra.
  • One case treats 120 acres if used at the lower rate of 0.13 L/ac and 80 acres if used at the higher rate of 0.19 L/ac.
  • Controls a full range of annual grasses at varying leaf stages and volunteer cereals when applied at a rate if 0.13 L/ac.
  • 0.19 L/ac controls the same annual grasses and volunteer cereals and also suppresses quackgrass at the 2 to 5-leaf stage. Use this rate if any one of the above mentioned conditions are not present at the time of application.
  • 0.44 L/ac controls the same annual grasses and volunteer cereals, as well as quackgrass, at the 1 to 3-leaf stage.
  • Also suppresses foxtail barley at the 1 to 6-leaf stage.

Note: Don’t forget to purchase Merge® surfactant.


Mixing Instructions

  1. Fill clean spray tank half full with clean water. Start agitation system.
  2. Add the correct amount of Poast Ultra. Continue to agitate.
  3. Add the correct amount of Merge along with the remaining amount of water necessary to fill the spray tank.
  4. Continue to agitate or run the by-pass system.After any break in the spraying operation, agitate thoroughly before spraying again.
  5. After any break in the spraying operation, agitate thoroughly before spraying again.


Will a reduced rate of Poast Ultra provide adequate weed control?

BASF conducts extensive research to determine the appropriate rate that will provide optimal control under a range of environmental conditions. Reduced rates are not recommended since they will probably provide inconsistent weed control.

Is it always necessary to add Merge?

Yes. Merge must always be added when Poast Ultra is used alone or tank-mixed with a broadleaf herbicide.

If quackgrass is in the 4- to 5-leaf stage, what type of control may be expected with Poast Ultra?

Normally, quackgrass should be sprayed in the 1- to 3-leaf stage for optimum weed control with Poast Ultra. If environmental conditions are good and the quackgrass is still actively growing Poast Ultra applied at the 4- to 5-leaf stage will provide acceptable control. A dense crop canopy will provide competitive pressure and aid control considerably.

What should be done if spraying of Poast Ultra is delayed?

The effectiveness of Poast Ultra should not be affected if spraying is delayed, even if the herbicide remains in the tank overnight. Ensure that proper agitation is carried out before recommencing spraying, to redistribute Poast Ultra or Merge that has settled out.

How long an interval should there be between application of Poast Ultra and other herbicides?

Allow 4-7 days between the application of Poast Ultra and any other chemical not recommended as a tank-mix combination on the label.

What effect does moisture have on the activity of Poast Ultra?

Poast Ultra is extremely rainfast. Only one hour is required following application. Additionally, dew has virtually no detrimental effect on Poast Ultra performance.

What effect does the environment have on Poast Ultra activity?

Poast Ultra is always crop safe, regardless of the environmental conditions. However, the performance of any herbicide is subject to environmental conditions. Increases in environmental stress, such as hot and dry weather, or particularly cool conditions will result in diminished herbicide performance. However, relative to other herbicides, Poast Ultra has proven to be the most effective across a broad range of environmental conditions.

Is Poast Ultra that has been frozen still "good"?

Poast Ultra does not freeze. Ensure that containers are well shaken before use.

Can Poast Ultra be tank-mixed with Basagran?

This tank-mix is not recommended.

Can Poast Ultra be tank-mixed with Embutox on alfalfa?

Poast Ultra is registered for use on alfalfa, however this tank-mix is not registered or recommended.