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Monolith is a new post-emergence herbicide formulated to tackle black-grass. For use in winter crops during spring, it provides 10% more control than Atlantis against black-grass. It partners two actives with exceptional grass-weed activity – mesosulfuron and propoxycarbazone. This combination means Monolith has the power to control a wide spectrum of grass-weeds on top of black-grass.

When should I use Monolith? 

Monolith is the final stage of a black-grass control programme following on from cultural controls and a robust pre-em. Use Monolith in spring from the 1 February and when the crop is at 3-leaf stage until 2nd node detectable (GS12–32).

Uptake is mainly through the shoots so there needs to be some active growth for the herbicide to take effect; care is needed for applications in February when conditions may be cold. Weather conditions at application are very important; apply to a dry leaf with sufficient drying time before dew forms.

Like other Bayer post-ems, applying Monolith when the target weed is small increases the overall level of control but conditions need to be right. Applying in cold or wet conditions is not advisable even if the plant is small because the active substances will not be taken in effectively.

How should I apply Monolith?

It is often said that the control from herbicides is 50% chemistry and 50% application and Monolith is no exception. The aim is to land the herbicide on the target leaf so it settles, dries and is taken in by the plant. To do this a fine spray, possibly fine-medium is required. Generally, the flat fan type nozzle produces a finer spray than the air inclusion nozzle.

Forward speeds should be no more than 12 km/h and make sure the sprayer boom remains stable to get a consistent application. Water volumes of 200 L/ha are suitable for Monolith. 

All applications should include 1 L/ha of the adjuvant biopower. There is also the option to include 0.3 L/ha Liberator as residual protection if you are expecting further spring germination of grass-weeds.

Is it worth switching from Atlantis to Monolith?

Every bit of control counts when fighting black-grass. At first glance, 10% more control may not seem an enormous amount but it means less competition for your crop and fewer seeds returned the following year. In trials comparing Monolith and Atlantis, Monolith resulted in 28 fewer black-grass heads as the graph shows. 

Crucially, these differences in head number affect yield. Based on AHDB Project Report 560 (Sustaining winter cropping under threat from resistant black-grass),

we can calculate that 30 fewer heads /m2 boosts yield by 0.3 t/ha. A useful boost to production and fewer black-grass seeds returned to the field too. The image below the improvements in control from Monolith against a range of grassweed at our Chishill weedscreen.

The final point, is that Monolith’s exceptional grass weed control is at the expense of some activity on broad-leaved weeds so consult the label before making the switch if you have been using Atlantis as an all-purpose spring herbicide. 

What is the difference between Hamlet and Monolith?

Both products control black-grass in winter wheat crops but Hamlet is for autumn and winter and Monolith is for use in spring. You can only apply one of these products to a wheat crop each season. There is a potential crossover in the application window for both products during February but growers planning a February application should opt for Monolith to give them flexibility to respond to conditions.

On a chemical level, both products contain mesosulfuron but Monolith combines it with propoxycarbazone while Hamlet is a three-way formulation with iodosulfuron and diflufenican.

Is it effective against resistant black-grass?

Monolith is based on mesosulfuron the same main active as Atlantis so it won’t transform the situation with resistant populations. However, the co-formulation with propoxycarbazone does offer a 10% uplift in control, even on populations with metabolic resistance. If cultural controls are keeping population at manageable levels, Monolith provides unbeatable in crop control of black-grass.

Will it control brome and other grass-weeds?

Monolith is highly effective against bromes. In five independent trials from 2016-17 Monolith gave class-leading control of brome populations. Growers should always incorporate resistance management by including varying modes of action and at least two cultural control methods.

Monolith easily matches the performance of Atlantis against rye-grass and meadow-grass if these are an issue on your farm.

Will the strong activity affect my crops this year or next season?

It is right to consider crop effects on any herbicides with strong grass-weed activity like Monolith. In season, the level of crop safety is equivalent to Atlantis i.e. safe if the label guidance is followed. For following crops, winter oilseed rape requires deep cultivation if Monolith is used.

What can I tank mix with Monolith?

Simple tank mixes with just Monolith + biopower and a residual partner if necessary give the best results but workloads mean that is not always possible. Applications with T0 or T1 is the main concern in early spring so pay attention to the fact that mixes with tebuconazole and chlorothalonil are not supported due to crop safety and antagonism respectively. Consult the tank mix guidance sheet for more details.

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