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.

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.

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.

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.

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.

• 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

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.

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.

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.

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.

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.

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

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.