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Bayer Roundup - The Roundup Difference



Roundup WeatherMAX® and Roundup Transorb® HC provide convenient, easy-to-use broad spectrum weed control even in tough conditions. And, thanks to years of top-tier research and development, these two Roundup herbicides also come with some of the best guarantees in the industry.

Roundup Products

Roundup WeatherMAX Herbicide

Roundup WeatherMAX Herbicide

There’s a reason growers continue to count on Roundup WeatherMAX to guarantee[*] performance and control the toughest weeds across a range of conditions. Its powerful formulation gives you confidence backed by our RiskShield™ protection package[*].

Growers choose Roundup WeatherMAX because it:

  • Ensures crop safety
  • Provides consistent weed control no matter the conditions
  • Offers great efficiency with a 540 g/L formulation
  • Backed by our RiskShield protection package[*]

Roundup Transorb HC

Roundup Transorb HC

Roundup Transorb HC herbicide provides excellent weed control and unbeatable value. It’s the perfect combination of performance, support and quality.

Growers like Roundup Transorb HC for:

  • Consistent, top-quality weed control
  • Proven performance
  • Trusted product service and support in the rare event it’s needed
  • The RiskShield Warranty[*]

Roundup Xtend herbicide with VaporGrip Technology

Roundup Xtend® herbicide with VaporGrip® Technology

This low-volatility liquid glyphosate and dicamba pre-mix formulation is specially developed for use in the Roundup Ready® Xtend Crop System. Through multiple modes of action, it helps manage tricky weed resistance and thanks to VaporGrip Technology, minimizes volatility potential—all in one convenient package.

Riskshield Protection Package

Riskshield Protection Package
Roundup WeatherMAX and Roundup Transorb HC herbicides are backed by a comprehensive package[*] of warranties and guarantees, placing them among the industry’s most reliable herbicides.
Roundup WeatherMAX
Roundup Transorb HC
Rainfast Guarantee
Service Plan
Crop Safety Guarantee
Crop Establishment Coverage
All Weather Warranty

Bayer has the most comprehensive service and warranty performance package on the market for glyphosate products. Roundup WeatherMAX® and Roundup Transorb® HC herbicides come with unique and comprehensive guarantees, for growers who want the assurance of guaranteed performance. Bayer’s RiskShield® Protection Package consists of the following benefits:

  • 30-Minute Rainfast Guarantee – If Roundup WeatherMAX® does not provide acceptable weed control due to rainfall 30 minutes or more after application, Bayer will replace up to the initial rate for re-treatment (640 acre maximum).
  • 60-Minute Rainfast Guarantee – If Roundup Transorb® HC does not provide acceptable weed control due to rainfall 60 minutes or more after application, Bayer will replace up to the initial rate for re-treatment (640 acre maximum).
  • Crop Safety Guarantee – Compatibility of Roundup Ready® crops is an integral part of the Roundup WeatherMAX® and Roundup Transorb® HC formulations. Bayer guarantees crop safety on over-the-top applications of these herbicides on plants containing Bayer licensed Roundup Ready® technology (640 acre maximum).
  • Crop Establishment Coverage – If a producer uses Roundup WeatherMAX® or Roundup Transorb® HC herbicide for a pre-seed burndown application, uses good agronomic practices, and the crop on the treated acres fails to establish — forcing a grower to reseed or fallow the field before July 1, 2021 — Bayer will refund or credit the grower the purchase amount for the Roundup WeatherMAX® or Roundup Transorb® HC used on those acres (640 acre maximum).
  • All Weather Warranty – If producers are forced to spray Roundup WeatherMAX® or Roundup Transorb® HC, even in tough conditions, and acceptable weed control is not obtained, Bayer will refund or credit up to the initial use rate of Roundup WeatherMAX® or Roundup Transorb® HC for re-treatment (640 acre maximum)

Bayer Technical Support –


Can I continue to use Roundup® branded glyphosate products on my farm today?
Yes, you can continue to use all: Roundup Transorb® HC Liquid Herbicide, Roundup WeatherMAX® with Transorb II Technology Liquid Herbicide, Roundup Xtend® with VaporGrip® Technology Herbicide, R/T 540 Liquid Herbicide and VisionMax® Silvicultural Herbicide products on your farm today.
Are any further changes anticipated for the glyphosate label?
No further changes are required for the glyphosate label. All new product formulated and shipped will contain the amended label.
Why were these label changes requested by the PMRA?
In April 2017, Health Canada’s PMRA granted continued registration of products containing glyphosate for sale and use in Canada after a rigorous eight-year re-evaluation. The majority of the changes to glyphosate-based herbicide labels were aimed at providing consistency in labels across all glyphosate brands, and introducing mitigation measures to further manage any potential environmental, human health, and occupational exposures.
Why were these changes made to the label?

Changes were made under the Commercial Agricultural Products portion of the label, regarding elements such as the reentry period, drift, environmental hazards, buffer zones and aerial application.

Roundup branded herbicides already provided label language speaking to these areas of safe application. The changes made by the PMRA were aimed at providing consistency in labels across all glyphosate brands and outlining additional safety precautions and additional mitigation measures to further manage risk.

What are the changes to the label?

PMRA has outlined some changes that will be required to be implemented. The large majority of these changes are aimed at providing consistency in labels across all glyphosate brands and to introduce mitigation measures aimed at further reducing environmental risks, human health risks, and occupational exposure. The key changes are as follows:

  1. Restricted Entry Interval (REI) – The restricted entry interval is 12 hours after application for all agricultural uses. Previously this information was not included on the label. It is being added to reduce occupational exposure.
  2. Additional precautionary statement on drift – The statement, “apply only when the potential for drift to areas of human habitation or areas of human activity such as houses, cottages, schools and recreational areas is minimal. Take into consideration wind speed, wind direction, temperature inversions, application equipment and sprayer settings” will be added to the label.
  3. Environmental Hazard Statements – additional statements will be added. E.g. “toxic to aquatic species.”
  4. Directions for use and buffer zone table - Will be updated. Essentially more detail and more specificity is being provided.
  5. Aerial Application Requirement – The statement, “take wind speed at flying height” will be added.
What is the best stage/time to spray a pre-harvest application?

Physiological maturity is the key for timing a pre-harvest glyphosate application. Physiological maturity is reached once seed moisture content is less than 30%. The table below provides visual indicators of physiological maturity.

Roundup Transorb® HC or Roundup WeatherMAX® herbicides should be applied at 0.67 L/ac for pre-harvest applications. Using 10 gallons of water per acre is recommended for dense crop canopies and for weeds that are hidden by the crop, such as dandelions. However, registered water volumes range from 5 to 10 gallons per acre. Crop canopy penetration is critical for successful weed control.

For detailed information on a pre-harvest application click here to download our digital Pre-Harvest Staging guide. Or call 1-800-667-4944 to request a copy.

Wheat, Feed Barley, Oats
Hard dough stage; thumbnail impression remains on seed
Canola Majority (75% - 80%) of pods are brown
Flax Majority (75% - 80%) of pods turned colour
Peas Lower pods (15%) are brown; seeds rattle
Lentils Lower pods (15%) are brown; seeds rattle
Dry Beans Stems are green to brown; pod tissue is dry and brown; 80% - 90% leaf drop
Soybeans Stems are green to brown; pods are mature (yellow to brown); 80% - 90% leaf drop (original leaves)
Forages 3 - 7 days before last cut in final year of stand
How and when is the best time to remove forage?

Fall Removal

  • The best time to remove forage from a rotation is in the fall. This applies the same principles used for controlling perennial weeds. The forage is building up root reserves to survive the winter and when Roundup WeatherMAX® and Roundup Transorb® HC are applied, it readily translocates down into the root system of the forage.
  • If the field has been grazed, the forage must be allowed to regrow 8-10 inches or more. Regrowth can be slow, especially if the stand is moisture stressed, so allow time for this growth prior to spraying.
  • Spray from mid-August onwards after the forage has adequate re-growth. Generally, the earlier the forage is sprayed before mid-August, the lower the control.
  • Registered use rates of Roundup WeatherMAX® and Roundup Transorb® HC vary from 0.67-1.33 L/ac. When removing forages, it is recommended to use 1.0-1.33 L/ac rates, as forage stands tend to be a mix of tough-to-kill species.
  • Tillage after treating is not necessary but can be performed if needed to prepare the field for the next spring. The tillage operation may enhance the control by exposing roots to frost and to drying out. Tillage can occur 7-10 days following Roundup WeatherMAX® and Roundup Transorb® HC application.

Spring Removal

  • Spring removal (May/June) is generally less effective than fall removal. It can be done using Roundup WeatherMAX® or Roundup Transorb® HC herbicides alone but spring control of alfalfa may be enhanced by adding 2,4-D.
  • If adding 2,4-D for spring removal, only cereal crops may be planted 14 days or more after using this treatment.
  • The forage should be allowed time to achieve new growth of 8-10 inches or more prior to treatment.

General Tips

  • If direct seeding into forages, follow-up treatments may be required.
  • Where possible, follow forage crops with a Roundup Ready® crop. This allows flexibility in crop treatment of weeds and forage survivors.
How does water quality affect Roundup® brand agricultural herbicides?

Good, clean water is very important to maximizing the performance of Roundup herbicide. Water free from dirt and soil particles is essential, as glyphosate readily binds to these particles. Glyphosate also binds easily (and tightly) to positively charged ions (cations) such as calcium (Ca), magnesium (Mg), Iron (Fe), and sometimes manganese (Mn) or zinc (Zn). When water contains a high level of these cations, it is refered to as hard water. Water hardness is usually measured in parts per million (ppm). Depending on the water volume being used, water can be unsuitable for use with Roundup herbicides at different levels of hardness. As a rule of thumb, any water that tests over 700 ppm should not be used with glyphosate, regardless of water volume. The following chart should be used as a guideline:

If the water hardness is above the recommended limits for intended use rate and water volume, the following measures can be taken to minimize the impact of hard water. The following recommendations are NOT a guarantee of overcoming the problem.

Roundup herbicide rate Water volume Hardness limit Comments
0.33L/ac – 0.67L/ac 5 GPA 700 ppm Do not use water volumes higher than 10 GPA when Roundup use rates are less than 0.33 L/ac
10 GPA 350 ppm
> 10 GPA Not recommended
> 0.67L/ac 5 GPA 700 ppm Because of possible precipitate problems, 700 ppm is still the threshold at 0.67L/ac with 5 GPA
10 GPA 700 ppm
> 10 GPA 350 ppm
  • Find another water source with softer water
  • Lower the water volume to decrease the amount of glyphosate tie-up – stay within acceptable water volume range as per the product label
  • Add ammonium sulphate (AMS). AMS comes in a dry (21-0-0-24) or liquid (8-0-0-9) form. Dry AMS should be added at a rate of 2% w/w (2kg for every 100L of water); liquid AMS should be added at a rate of 1% v/v (1L for every 100L of water).
  • Increase rate of Roundup by 10-15% to offset any tie-up – stay within labeled limits
Do Roundup agricultural herbicides require heated storage?
Roundup® brand agricultural herbicides do not require heated storage. Roundup® brand agricultural herbicides may be stored at cold temperatures; the product will not freeze, however it may thicken slightly. Agitate well prior to use (transportation to field is often enough agitation).
How much Roundup brand herbicide do I mix in a backpack or hand-type sprayer?
When spraying annual weeds, mix a 0.67 percent solution of the product in water. For harder to control perennial weeds, mix a 1.34 percent solution of the product in water. These recommendations can be found in the “Application Equipment” section of the product label.
How soon can I spray an in-crop application in Roundup Ready® crops after a frost?

Two things to be concerned about with a frost on your Roundup Ready® crops – weed control and crop tolerance. The weeds will be affected by a frost much the same way they would be if it were a pre-seed application. Similarly, the crop must also have time to recover from the frost to minimize crop injury.

0 to -4°C: Wait at least 24 hours to assess damage to the weeds and the crop. Spraying can resume if forecasted temperatures are to remain higher than 8°C for a minimum of 2 hours after the application.

≤ -5°C: Wait at least 2 days to assess damage to crop and weeds. Spraying can resume if forecasted temperatures are to remain higher than 8°C for a minimum of 2 hours after the application.

Weeds must be >60% green and actively growing for good results and Crop needs to show signs of regrowth before spraying can take place.

Does this label amendment affect all glyphosate or only legacy Bayer’s brands?
The re-evaluation of glyphosate and the consequential label amendments are applicable to all glyphosate labels. Please direct all questions regarding other glyphosate labels to their applicable manufacturer.
Was the product unsafe for use under the current/previous label?
No. The PMRA confirmed the safety of glyphosate, which has a 40-year history of safe use in 160 countries around the world. The PMRA conducted a standard re-evaluation process and implemented the required changes to ensure the label remains current in today’s regulatory environment. Bayer fully supports the implementation of the label amendments.
What were the conclusions from the PMRA’s Re-evaluation in 2017?

PMRA reaffirmed the safety of glyphosate, stating:

  • It is not genotoxic and is unlikely to pose a human cancer risk;
  • Dietary (food and drinking water) exposure associated with the use of glyphosate is not expected to pose a risk of concern to human health;
  • Occupational and residential risks associated with the use of glyphosate are not of concern, provided the updated label instructions are followed;
  • The environmental assessment concluded that spray buffer zones are necessary to mitigate potential risks to non-target species (e.g. vegetation near treated areas, aquatic invertebrates and fish) from spray drift;
  • When used according to revised label directions, glyphosate products are not expected to pose risks of concern to the environment;
  • All registered glyphosate uses have value for weed control in agriculture and non-agricultural land management.
What temperatures are required for spraying?

Pre Seed Burnoff: If the daytime temperature is forecasted to reach a minimum 8-10°C, plan to spray once the temperature reaches a minimum 5°C. It is best to spray in the morning or afternoon as temperatures rise throughout the day. Avoid application into the evening if the temperature is to drop below 10°C. In this case, stop spraying 1.5 to 2 hours before sunset or before it drops below 10°C. This allows time for the product to move from the leaves to the growing points of the plants.

In Crop: Try to avoid the heat of the day as plants will grow less actively in extreme heat; Bayer Canada does not recommend spraying in temperatures above 30°C. Spraying later in the day or into the evening is fine as well, but spraying in the morning allows the plants to ‘recharge’ overnight – be careful of excessive dew on the plants as this may cause the herbicide to run off the plants resulting in reduced control.

Pre Harvest: Evening and early morning temperatures of 0 to -4°C should not impact the performance of Roundup agricultural herbicides for pre harvest as cool seasonal temperatures have conditioned perennial weeds. However, do not start applying until late morning or afternoon and only apply if forecasted temperatures are to remain higher than 8-10°C for a minimum of 2 hours.

Post Harvest: If forecasted daytime temperatures are a minimum of 8-10°C, start spraying in the morning provided there has not been a killing frost and the dew or snowmelt is not causing the herbicide to run off the plant. The weeds need at least 2-4 hours of temperatures above 8-10°C to translocate the Roundup brand agricultural herbicide. With cool temperatures, stop spraying 2 hours before sunset.

When can grazing resume after spraying Roundup brand herbicides?

Proper translocation prior to animal re-entry is imperative to effective weed control. To ensure proper weed control and forage removal, Bayer recommends grazing not resume for 3 to 5 days after spraying.

  • Grazing is safe for the animals as soon as the herbicide has dried. However, proper translocation must occur before grazing is allowed to ensure proper weed control.
  • When a Re-entry Interval is not listed on a chemical label, it is recommended to wait until the chemical has dried, however, assume annual weeds require a minimum of 24 hours of good weather conditions for proper translocation.
  • For perennial weed and forage control, wait a minimum of 72 hours for proper translocation of the chemical through the target plants before allowing grazing.

Allowing animals to graze earlier may result in reduced control.

What products can I mix?

Can I mix Roundup brand agricultural herbicides together?
Mixing Roundup brand agricultural products together (for example Roundup Transorb® HC and Roundup WeatherMAX® ) is fine, however, because of formulation differences, be aware that the rainfast period will only be guaranteed to that of the longer rainfast guarantee (which in this example is Roundup Transorb HC – 60 minutes).

Can I mix Roundup brand agricultural herbicides with other glyphosates?
Monsanto Canada will not guarantee performance of Roundup brand agricultural herbicides when tank mixed with other glyphosates.

Can I tank mix insecticides with Roundup® brand agricultural herbicides?
Yes, Decis® insecticide is a Bayer supported tank mix option with Roundup® brand agricultural herbicides in Roundup Ready® Canola and Roundup Ready Corn.

Can I still spray Roundup brand herbicide if the weeds are covered in dust?

Glyphosate binds very tightly to soil particles, including small dust particles. Dust on the leaves can deactivate Roundup once it contacts the leaf surface.

How do I determine if there is too much dust on the leaves?
A quick way to determine if there is too much dust on the leaves is to wipe your thumb across part of the leaf. If you can see a definite mark where you have wiped, there is too much dust on the leaves, and you may not see optimal performance.

How do I overcome dust on the leaves?

  • Increase the rate of herbicide by approximately 25% (Ensure you are still within labeled rates)
  • Increase water volume to penetrate dust
  • Wait for a rain or dew to wash the dust off the leaves
How long after spraying do I have to wait before I seed or till?

Annual Weeds: When applying Roundup WeatherMAX® under good growing conditions, seeding may start 4-6 hours later! For all other Roundup brand agricultural herbicides (or under stressful weather conditions), you must wait a minimum of 24 hours before seeding or working the land.

Perennial Weeds: With all Roundup brand agricultural herbicides we recommend that you wait 72 hours under good growing conditions before seeding or tillage. If it’s cool and cloudy wait an extra day before tillage so the herbicide has sufficient time to translocate to the roots of the weed.

Post harvest spraying – how tolerant are weeds to frost?
The effect of frost on weeds depends on the length and harshness of the frost. In general terms, dandelions are the most tolerant to frost, while perennial sow-thistle and Canada thistle are the most sensitive. If in doubt, it is best to wait a day or two after the frost and assess the damage to the weeds – if they are still 60% green, they should still be susceptible to Roundup brand agricultural herbicides.
How do I control volunteer Roundup Ready canola?
Please visit for complete details on best practices for controlling Volunteer Roundup Ready canola.