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Atlantis WG

As the leading post-emergence herbicide for use on black-grass in winter wheat, we recommend that you put Atlantis WG at the centre of your black–grass control strategy. Used as part of a programme – preferably in the autumn – it offers good control of both black-grass and rye-grass.

Optimise Atlantis WG applications

When it comes to herbicide applications black-grass is a notoriously tricky target. At the one to three-leaf timing - when Atlantis WG (mesosulfuron and iodosulfuron) is most effective - black-grass is only 2-3 cm tall with thin vertical leaves just millimetres wide.

Atlantis WG is a contact herbicide. That means it is absorbed through the leaves of the plant. For optimum effect, spray droplets must hit the target and remain there for at least two hours to allow sufficient uptake by the weed.

Black-grass not only has a minimal leaf area, but it’s hairless and often waxy surface means application technique can make a big difference, according to Phillippa Overson, the combinable herbicide campaign manager at Bayer CropScience. This year’s conditions demand careful attention to detail to optimise efficacy, she says.

“This autumn’s good growing conditions have resulted in thick crop canopies, which make it more difficult for spray to reach its target.


Ms Overson says that by increasing water volume, growers can increase the amount of spray that penetrates the canopy. “For guidance we normally recommend spray volumes of 100L/ha in autumn and 200L/ha in spring. The difference normally takes into account thicker crops going into the spring but circumstances this autumn could justify upping water volumes if conditions continue to promote growth.”   


Growers should look to apply post-ems sooner rather than later, advises Ms Overson.  As plant size is the dominating factor in the efficacy of post-em, application at the 1-3 leaf stage (GS11 – 13) is crucial for achieving a satisfactory result


Try to apply Atlantis WG to a dry leaf and allow drying time. At this time of year that can be difficult, so take a sensible judgment. If the choice is between spraying Atlantis WG after rain but going into dry weather, or applying it to a dry crop with heavy rain forecast imminently, always do the former. Although it will take longer for the product to dry onto the leaf, it’s better than seeing it wash off within just a few hours.


“We’ve tested the impact of different nozzles with Atlantis WG and flat fans are the most reliable and remain our recommended choice,” points out Ms Overson. “That’s not to say on a particular day in the right crop and target other nozzles, or angled nozzles, may do a good job. But where there are different sized black-grass plants or the wind is likely to change direction, a flat fan will give the most reliable results.”


Speed is important too. Bayer recommends 12km/h maximum speed and while variable rate regulators automatically adjust the pressure if you travel faster, the spray quality is affected and with such a small target, it’s not worth the risk. If speed is doubled, pressure is quadrupled and that will turn a fine/medium spray into spray so fine it is off the scale and with a much higher potential to drift. Fine droplets have less kinetic energy and are less likely to go where you intend, you need some weight to get the momentum and the accuracy.


Finally, don’t forget the adjuvant! The most effective to use with Atlantis WG is bioPower; it is a very important aspect of the tank-mix. It helps the Atlantis WG to stick to the thin leaves of black-grass plants and will optimise efficacy.

Remember, at post-emergence you’ve only one chance to hit the target with your contact product. It’s important to make sure you get everything right.


Why Atlantis WG for Black Grass Control?

A combination of chemical and cultural control is needed to effectively deal with black-grass. Used correctly, as part of a programme and together with cultural control, Atlantis WG offers the best post-emergent black-grass control available. It is also effective on rye-grass, mayweed and chickweed. Research has shown that using Atlantis WG can reduce losses due to black-grass by as much as five tonnes per hectare. 

Main advantages

  • Most effective post-emergence herbicide for treating black-grass and rye-grass in winter wheat
  • Also controls some broad-leaved weeds
  • Most effective when used as part of a programme
  • Dust-free granular formulation
  • Excellent pouring properties
  • Easy to transfer to the sprayer and easy to clean
  • Winter oilseed rape (after ploughing), winter wheat and winter barley may be drilled the following autumn
  • Spring oilseed rape, sugar beet, spring wheat and spring barley may be drilled the following spring

Getting the best from Atlantis WG

To get the best out of Atlantis WG, we recommend that you use it as part of a programme on small, actively-growing weeds in the autumn. The use of a suitable adjuvant increases the uptake of Atlantis WG by the leaves of the susceptible weeds. We recommend our adjuvant biopower, which has consistently outperformed other adjuvants in improving the performance of Atlantis WG. It is also important to avoid complex tank-mixes.

Important things to remember

  • Always use as part of a programme
  • When used before February, tank-mix with an effective residual partner
  • Don’t use alongside chlorpyrifos as this may result in crop damage
  • Pay close attention to application including: water volume, spray quality (fine to medium), boom height and make sure you get good weed coverage
  • Remember you can only use one ALS grass-weed product such as Atlantis WG on the same crop

Atlantis WG as part of a programme

We advise you to always use Atlantis WG as part of a programme. This should include cultural controls such as the use of stale seedbeds, as well as an effective non-ALS pre-emergence herbicide such as Liberator (flufenacet and diflufenican). Atlantis WG works best when applied to actively-growing small weeds in the autumn. It should be tank-mixed with an effective residual partner.

Watch this short video where Ben Giles talks about Atlantis WG and its place in your black-grass control programme.


Product Summary

 Formulation    Atlantis WG is a dust-free granular formulation that has excellent pouring properties   allowing easy transfer to the sprayer. In the event of a spillage the product is easier to   clean-up than a liquid formulation.
 Pack size  2kg
 Active   substances  mesosulfuron-methyl (30g/kg) and 
 iodosulfuron-methyl-sodium (6g/kg).
 Safener  mefenpyr-diethyl (90g/kg)
 Use rate  400g/ha.
 Mode of   Action  ALS Inhibitor
 Crops  Atlantis WG may only be used on winter wheat (all varieties).
 Timing of   application  GS 12-13 of the grass weed when the majority have emerged
 Weed   Spectrum  Atlantis WG provides very high and consistent levels of control
 of black-grass and rye-grass.


biopower is our adjuvant for use with Atlantis WG and Pacifica.

Because these products act primarily via uptake by the leaves of susceptible weeds, the use of an adjuvant increases uptake. This increased uptake not only enhances the rainfastness of Atlantis WG and Pacifica, but also increases the reliability of the performance under a wide range of environmental conditions.

Our trials have demonstrated that biopower consistently outperforms other adjuvants in increasing the efficacy of Atlantis WG and Pacifica and in enhancing consistency of performance from season to season. These trials have also shown that the use of some adjuvants can be detrimental to the efficacy of these products.

Use biopower at 1 L/ha in order to maximise the efficacy and rainfastness of Atlantis WG and Pacifica.

ALWAYS add biopower to the spray-tank last. Switch off the induction bowl immediately after adding biopower since this can introduce air into the spray-tank and result in excessive foaming.


Dont wait until March

Waiting until March could rob you of two tonnes per hectare

Black grass early treatment chart

Don’t wait until March to treat your black-grass with Atlantis WG. The longer you wait, the bigger the black-grass, which puts more pressure on the herbicide, and increases the yield loss from crop competition. Many growers wait for traditional spring conditions before using Atlantis WG, but earlier treatment - while there is less competition -  will give better control and better yields.

In our Chishill weed screen last year treatment in the middle of February gave around 85% control of black-grass, but this fell to only 65% by the end of March. Trials have shown that leaving your treatment until the end of March can result in average losses of 2 tonne/ha worth around £290.

Treating early will also help where enhanced metabolic resistance (EMR) is a concern, as EMR plants are easier to control when at early growth stages.

These dramatic pictures show just what a difference early treatment makes, not only to black-grass but to bromes and rye-grass too.


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