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Trials prove there is an answer to beating resistant black-grass

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Average herbicide spend has doubled over the past six years yet black-grass is still on the increase in many areas, highlighting an urgent need for farmers to adopt more effective solutions.

That is the warning from leading agronomy firm Hutchinsons ahead of its annual open days at the National Black Grass Centre of Excellence in Brampton, Cambridgeshire on 22-23 June 2016.
Technical manager Dick Neale says a typical arable farm now spends around £180/ha on herbicides, yet black-grass and herbicide-resistant populations in particular, are becoming ever more prevalent. Indeed, resistant black-grass has been confirmed in 34 counties in England and is on the increase in Scotland and Cumbria too, according to industry figures.

However, six years of in-depth trials at the Hutchinsons site prove high populations of resistant black-grass can be significantly reduced with a range of cultural and chemical options that are financially and environmentally more sustainable than just costly multiway stacks of chemistry.

Emerging black-grass levels have been slashed from 700 per square metre pre-sowing six years ago to just 60 today and can be maintained at this level long-term, says Mr Neale, who will reveal details to this success at the open days later this month.

“Since we started the trials in 2010, average spending on herbicides [across the industry] has roughly doubled, which is unsustainable from both an economic and resistance management point of view.

“Yet we’ve shown that employing effective cultural measures throughout the rotation followed by a well-timed residual herbicide is the best way to maximise black-grass control.”
Mr Neale says the most effective cultural options include:

  • Rotation and crop choice: Spring cropping (especially barley) offers a wider window for autumn black-grass control. Select competitive crops and varieties (e.g. hybrid barley) that can establish well in the farm conditions and compete with black-grass
  • Seed rate: higher rates boost crop competition – up to 450 seeds/m2. Allow for lower establishment when sowing late or if spring cropping on heavy land
  • Delay drilling: allows more time for black-grass to emerge in autumn and be controlled before a crop is sown (e.g. through stale seedbeds) – around 80% of black-grass emerges between September to October
  • Shallow cultivations: restrict cultivations to the top 50mm of soil to maintain a “kill zone” where black-grass can be stimulated to emerge and be controlled. Avoid bringing seed up from depth by ploughing or subsoiling.

Employing a range of effective cultural measures will reduce black-grass to a level that gives herbicide chemistry a better chance of achieving the required level of control, providing it is applied at the right time in optimum conditions, Mr Neale continues.

In winter wheat, pre-emergence Liberator (diflufenican + flufenacet) applied to winter wheat sown late on 23 October at 450 seeds/m2 delivered 93% control. This was only achieved by careful application timing after reducing black-grass to a manageable level (52 plants/m2) with cultural measures, he says.

“Flufenacet offers good control and excellent crop safety, which is vital if we are to avoid taking the vigour out of the crop and reduce its ability to compete. Utilising Liberator/Vigon/Crystal pre-em and then following up post-em using one or two other active ingredients with the focussed use of an adjuvant will get us to almost 100% control.”

Depleting the seedbank through such an integrated approach and maintaining low populations with careful crop management - tailored to individual sites - is the only effective way of controlling black-grass as chemical options become more limited, he adds.

Discover more about the Brampton black-grass research and what it could mean for your farm at the open days on Wednesday 22 and Thursday 23 June 2016. Visit www.hlhltd.co.uk/brampton2016.html to book your place.

The website also includes a series of six short cultivation videos featuring Dick Neale demonstrating the effects of ‘conditioning crops’ and different soil management regimes on soil health. See www.hlhltd.co.uk/cultivationvideos.html