Freedom From Wild Oats

When it comes to wild oats, you want total confidence that troublesome weeds can be beaten. With Varro’s powerful ability to win the battle against wild oats and other problematic grass weeds, including Group1-resistant biotypes, Varro is a proven resistance management tool. In addition, Varro offers you the freedom and flexibility to rotate back to sensitive pulse crops like dry beans and lentils.

Varro vs Competition

Varro is also a strong performer on other grassy weeds including barnyard grass, Persian darnel, green foxtail, yellow foxtail, canary seed and Japanese brome.

Early Weed Removal To learn more about how you can achieve a 10% yield increase with Varro herbicide, click here.


Boost Your Broadleaf Weed Control

Varro is much more than a solo act - it contains a "broadleaf booster", which will enhance the performance of all broadleaf herbicides Varro is tank mixed with. Furthermore, it also partners well with other broadleaf herbicides to target specific weeds on your farm, and is an ideal tank mix with Buctril® M and Thumper®.

The orange portion in the charts below show research trials performed measuring the increased levels of dicot weed control you get when tank mixing Varro with Buctril M and Thumper.

Varro Broadleaf Booster

How to improve control of tough weeds

Varro can effectively battle Group-1 resistant wild oats. The chart below shows how Varro stacks up against the competition.

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Click here for the Varro Fact Sheet

Active Ingredients

Thiencarbazone-methyl – Group 2

Weeds Suppressed

Grassy Weeds
Japanese Brome
Persian darnel
Yellow foxtail

Broadleaf Weeds
Round-leaved mallow
Russian thistle

Province of Registration

British Columbia

Approved Tank Mixes

Spring Wheat

  • AMS (spring wheat only)
  • Attain® XC
  • Barricade®
  • Buctril® M
  • Broadside®
  • Curtail® M
  • Frontline™
  • Grow TTF™
  • Infinity
  • MCPA Ester
  • Momentum™
  • NIS
  • OcTTain™
  • Paradigm™
  • Pixxaro™
  • Prestige® XC
  • Refine® SG
  • Retain SG
  • Refine SG + 2,4-D Ester
  • Refine SG + MCPA Ester
  • Stellar®
  • Tilt
  • Thumper®
  • 2,4-D Ester

Durum wheat

  • Attain® XC
  • Barricade®
  • Broadside®
  • Buctril M
  • MCPA Ester
  • NIS (Non-ionic surfactant)
  • OcTTainTM
  • Prestige® XC
  • Refine® SG
  • Retain SG
  • Thumper
  • 2,4-D Ester

Get the Max from your Tank Mix

For a complete list of off-label tank mixes supported by Bayer, please see: Tank Mix List

Application Guidelines


  • Strong performance on grassy weeds such as wild oats, barnyard grass, Persian darnel, green foxtail, yellow foxtail, canary seed and Japanese brome
  • “Broadleaf booster”: Varro’s activity on select broadleaf weeds enhances the performance of all broadleaf tank-mix partners, including Buctril® M and Thumper®
  • Varro supports crop rotation flexibility to sensitive crops like lentils and dry beans
  • Wide window of application 1 to 6 leaf stage, plus 3 tillers, but before first node (jointing)
  • Registered for application by both ground and air


Application Tips

  • Bayer research has shown that adding AMS to Varro herbicide can increase wild oat control by 5-10% under cool conditions and heavy weed populations
  • Bayer recommends the addition of AMS on spring wheat
  • Bayer recommends using a Non Ionic Surfactant (NIS) in durum wheat rather than AMS in durum wheat, as durum is more sensitive to crop injury
  • One 10 L jug of AMS will treat 20 acres


0.20 L/ac.


  • Apply Varro from the 1 to 6 leaf stage on the main stem up to emergence of the 3rd tiller, but before appearance of the first node (jointing)
  • Avoid crop injury: do not apply an ALS herbicide such as Varro following the appearance of the first node


  • Under drought conditions: do not spray Varro herbicide if >35 days between seeding and spraying, as drought hastens crop development
  • Do not spray within three days before or after cold temperatures (3°C or lower)


One 8 L jug = 40 acres (one 2 X 8 L case = 80 acres)


Water Volume
  • Ground – minimum of 5 US gal./ac. (19 L/ac.)
  • Aerial – minimum of 3 US gal./ac. (11 L/ac.)


One hour after application


Residue and Grazing

Do not:

  • graze the treated crop or cut for forage hay within 7 days or cut for hay within 30 days of application
  • harvest wheat (spring or durum) for grain or straw within 60 days of application or winter wheat within 72 days of application
  • re-enter treated fields within 12 hours of application


Re-cropping Intervals
Safe to plant within 10 months following Varro application: alfalfa, barley, canary seed, canola, chickpeas, corn (field), dry bean, flax, lentils, mustard, oats (spring), peas (field), soybeans, sunflowers, timothy and wheat (spring, durum, and winter).



What is Varro™?
Varro is a Group 2 herbicide that contains the active ingredient thiencarbazone-methyl which provides grassy weed control and activity on certain broadleaf weeds.

What crops can I safely apply Varro to?

  • Wheat – spring, durum and winter wheat.

What grassy weeds will Varro control?

  • Controls: Wild oats, green foxtail, barnyard grass and canary seed.
  • Suppresses: Persian darnel, yellow foxtail and Japanese brome.

What is a "broadleaf booster"?

  • Varro contains a “broadleaf booster” which means Varro will boost or enhance the dicot weed control of its many broadleaf tankmix partners.

What broadleaf weeds will Varro control?

  • Controls: Cleavers, hemp-nettle, pale smartweed, redroot pigweed, shepherd’s purse, stinkweed, volunteer canola, wild buckwheat and wild mustard.
  • Suppresses: Lamb’s-quarters, round-leaved mallow and Russian thistle.

Does Bayer recommend a broadleaf tank-mix partner for Varro? If so, which one?

  • Yes. In the brown/dark brown soil zone, Thumper or Buctril M are excellent tank mix partners. If targeting perennial weed control, Prestige™, Barricade®, Momentum® and Stellar® mix well with Varro. Other approved tank-mix partners include 2,4-D Ester, AMS, Attain, Broadside, Curtail M, Frontline, Grow TTF, MCPA Ester, OcTTain, Paradigm, Pixxaro, Refine SG, Retain SG and Tilt. Do not mix with products containing dicamba (Pulsar). Add AMS when mixing with Prestige, Curtail M or Momentum.

Will Varro control my Group 1-resistant wild oats?

  • Yes, Varro is a Group 2 and therefore is an excellent tool to control Group 1-resistant wild oats. It can also be used in rotation to prevent Group 1 herbicide resistant wild oats from becoming a significant problem.

Can I add Ammonium Sulphate (AMS) for enhanced weed control?

  • AMS can be added to Varro in spring wheat for improved activity on wild oats. The benefit of AMS will be more pronounced under cool conditions or heavy populations. Do not add AMS to Varro on durum wheat as durum is more sensitive to crop injury. (Non-Ionic Surfactant) NIS can be added to durum wheat.

I heard that I can plant back to lentils the year after applying Varro. What other crops can I plant back to?

  • Varro has a very flexible re-cropping profile and it is safe to plant the following crops 10 months after applying Varro: alfalfa, barley, canary seed, canola, chickpeas, field corn, dry bean, flax, lentils, mustard, oats, field peas, soybeans, sunflowers, timothy and wheat (spring, durum or winter).

What crop stage can Varro be applied to?

  • 1-6 leaf stage up to 3 tillers, but prior to appearance of the first node (jointing). Optimum weed control, crop tolerance and crop yield will be obtained when Varro is applied at the 3-4 leaf to 1 or 2 tiller stage of the crop and weeds.

How does drought stress affect the plant and ability to apply Varro?

  • Under drought conditions:
    • Do not spray an ALS herbicide such as Varro >35 days between seeding and spraying, as drought hastens crop development; the plant matures more quickly, reaching maximum application stage sooner.
    • Do not spray within 3 days before or after cold temperatures (3 °C or lower).

What is the mixing order?

  • Add Varro first, followed by other liquid herbicides.
  • If adding AMS, always put AMS in the tank first. Add Varro to a significant amount of water (a moving stream of water in chemical handler or directly into a half-full spray tank of water). If using a small amount of water, a gel may be visible; this is easily rinsed away with additional water.

Resistance Management

Resistance Management

Discover how Varro® herbicide and its Group 2 mode of action can help you manage costly and damaging herbicide-resistant weeds.

Varro herbicide – Freedom from wild oats

  • Varro provides strong performance on grassy weeds such as wild oats, barnyard grass, Persian darnel, green foxtail, yellow foxtail, canary seed and Japanese brome
  • Group 2 technology allows for control of problematic Group 1-resistant wild oats and foxtail
  • Varro enhances the overall control of its broadleaf tank-mix partners
  • Allows you to move freely and safely from wheat to barley without stopping

What is Resistance?

Resistance is a naturally occuring, inherited ability of some weed biotypes to survive a herbicide treatment that should, under normal use conditions, effectively control a weed population. Some herbicide resistant weeds have naturally developed one or more mechanisms that allow them to survive a herbicide treatment.

For a weed to be considered resistant it must:

  • Normally be controlled by the herbicide
  • Survive a usually lethal dose of the herbicide
  • Be heritable, meaning it is passed from generation to generation

Herbicide-resistant individuals are naturally present within a weed population at very low frequencies.

Did you know that there are over 20 Group 1 herbicides on the market?

What's the impact to farming in Western Canada?

Why is it important to you?

The management issues and yield concerns with herbicide resistance are very real, especially now with an increasing number of herbicide resistant weeds spreading across Western Canada.

Loss of viable herbicide options

  • Have to rely on currently available herbicides for the foreseeable future
  • No herbicides with new modes of action are in advanced trials

Would require changes in weed and crop management practices

  • Zero or reduced tillage rely heavily on herbicides for weed control

Reduced return on investment

  • Increase the cost of weed management
  • Loss of yield potential

The number of weeds with herbicide resistance continues to rise

  • Including weeds resistant to multiple modes of action

How does resistance develop?

The image below demonstrates the interaction between a weed species and a particular mode of action and the development of herbicide resistance at different speeds. It’s clear to see that over time the use of a herbicide quickly changes from being very effective to becoming extremely ineffectual. In fact, by the fifth year of application the herbicide is failing to eliminate herbicide-resistant weeds. It is particularly alarming that there is a dramatic increase in failure rate from the fourth to fifth season.

Development of Herbicide Resistance

% Resistant Weeds in Population Weed Control
0 Application .0001% Excellent
1st Application .00143% Excellent
2nd Application .0205% Excellent
3rd Application .294% Excellent
4th Application 4.22% Excellent
5th Application 60.5% Failure
Source: Weed Science Society of America, 2011

What can you do to delay the onset of herbicide resistance?

  • Don’t rely solely on herbicides for weed control
  • Develop field-specific long-term weed management plans
  • Rotate herbicide groups year over year

General guidelines for herbicide rotations:

  • Avoid repeated use of the same herbicide or herbicides having the same mode of action in the same field year to year
  • Limit the number of applications of a single herbicide or herbicides having the same site of action in a single growing season
  • Use mixtures or sequential treatments of herbicides having different modes of action which are active on the same target weeds whenever possible
  • Use non-selective herbicides pre-seed or pre-emergence to control early flushing weeds (prior to crop emergence) and/or weed escapes

Resistant weed management strategies

  2. Rotate crops as often as possible to utilize the unique modes of action available within the crop.

  4. Time and place fertilizer to benefit your crop, not weeds.

  6. Systematically target problem weeds and respond quickly to changing weed populations.

  8. Scout often and take note of individual weed response to all applications (pre-emergent, post-emergent and pre-harvest).

  10. Make sure you remove all weeds before they set seed – even if you have to pull by hand. Remember the old English proverb: One year seeding, seven years weeding.

  12. Leaving a 1m wide weed-free zone around your cropping fields (so new weeds can’t propagate and expand throughout your fields).

  14. Decrease your row spacing and increase seeding rates to optimize plant populations, maximize crop competitiveness and minimize time to crop canopy closure.

    • Match selection of herbicide(s) with your most difficult weeds.
    • Use full-labelled rates.
    • Include the best tank mixes and adjuvant(s).
    • Use correct spray volume (follow label directions).
    • Use correct nozzle spacing and droplet size.
    • Don’t spray at excess travel speeds, follow label directions.
    • Apply during the best weather conditions (warm, humid, and sunny conditions with minimal wind).
    • Maximize rain-fastness intervals.
    • Time of day (herbicides are most effective when sprayed between 8:00am and 9:00pm).

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Herbicide resistance is everyone's problem. This product is a Mix It Up solution.

Visit for more simple strategies and solutions.


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