Alternative herbicide in battle against black-grass

Positive feedback from growers, together with good results in distributor trials has prompted Dow AgroSciences to reposition its pyroxsulam+pendimethalin herbicide, Broadway Sunrise, for the coming season.

Dow launched the herbicide at Cereals 2010 to target what it claimed to be the widest-ever range of grass and broad-leaved weeds in winter wheat.

The original positioning was for autumn use, as part of a programme, with optimum application timing at the 1-3 leaf stage of target grass-weeds and between crop growth stages 11-29.

Speaking in 2010, Dow’s Stuart Jackson said Broadway Sunrise would be appropriate where black-grass was one component of a mixed weed spectrum, but not where it was the driver of a herbicide strategy, making it particularly suitable for the west and north regions.

Good control

However, according to Dow, a year of commercial use plus distributor and other trials has demonstrated Broadway Sunrise can offer black-grass control on a par with current market leader Atlantis (iodosulfuron+mesosulfuron), where it is applied in the autumn after a robust pre-emergence treatment.

"The past year has seen extensive use by growers across the UK, with great results.

"In addition, there have been trials undertaken by our distributors and others. We have gathered this experience together to refine our recommendations, particularly on black-grass,” says the company’s Vaughn Stansfield.

In four trials in 2011, in Yorkshire, Lincolnshire and Cambridgeshire, a programme of pre-emergence Liberator (flufenacet+diflufenican) followed by Broadway Sunrise applied at the optimum 1-2 leaf stage of the weed gave more than 90 per cent control of black-grass, equal to a programme of full rate pre-emergence Liberator followed by Atlantis+800gai/ha pendimethalin.

However, key to Dow’s recommendations for use of Broadway Sunrise is its application in a sequence containing a minimum of 240g ai/ha of flufenacet applied pre-emergence.

Pre-emergence Crystal (fluf-enacet+pendimethalin) is not an option, since Crystal’s 4l/ha application rate would exceed the maximum permitted pendimethalin total dose of 2000g/ai/ha per crop.

Additional residual herbicides, including Defy (prosulfocarb), or flufenacet+diflufenican+flurtamone (Movon/Vigon), can be stacked into the programme as appropriate, says Mr Jackson.

Vital first step

"No matter what the autumn throws at you, the starting point for the programme is the pre-emergence. An early pre-emergence is the first vital step.

"A flufenacet-based product, applied shortly after drilling, forms a solid foundation for the programme.

"Waiting for the so-called ‘peri-emergence’ timing, when the crop is beginning to emerge is too late as by then black-grass is also emerging and will be les effectively controlled.

"You then just have to be really mindful that you have got to get back in (to the crop) when black-grass reaches the 1-2 leaf stage and weeds are growing actively in the autumn.

"With both residual and contact action, this treatment will take care of the weeds that are growing away from the pre-em, as well as those that are still emerging” he adds.

Broadway Sunrise is an ALS inhibitor and, with the same mode of action as Atlantis, offers no alternative to Atlantis in terms of management of resistant black-grass. It is likely to be priced at a similar level to Atlantis within a programme, says Dow.

The company is also supporting use of Broadway Sunrise for black-grass control in the spring, up to growth stage 29 of the crop or black-grass at four tillers, but stresses best results will come from autumn applications as part of a programme.

Broadway Sunrise also offers benefits over Atlantis in terms of control of bromes and rye-grass and some broad-leaved weeds, such as cranesbill and groundsel, adds Mr Jackson.