Get pre-emergence herbicides on early
Pre-emergence herbicides should be applied as soon as possible after drilling to maximise blackgrass control, even if field conditions are dry, say experts.
The most effective chemistry for killing blackgrass is at the pre-emergence timing, with flufenacet-based products such as Crystal and Liberator.
Their efficacy diminishes the later they are applied, despite being approved for use up to early tillering in winter wheat and barley.
Agrivice agronomist Dan Robinson believes growers need to get timings correct – ideally immediately after drilling.
“If you miss that timing, achieving adequate blackgrass control becomes a lottery. The materials are for pre-emergence and the days of drilling the whole farm before spraying are gone, whether you are running a large or small unit,” he says.
Agronomists’ top blackgrass tips
Dan Robinson: “Rotational ploughing should be a key component of cultivations and ensure that seed-bed quality is as fine as possible.”
Mike Thompson: “Use the low blackgrass dormancy to get the most out of stale seed-beds this year.”
Damian McAuley: “Don’t farm on last year’s experience and drill too early, stack pre-emergence herbicides and use Avadex in the worst situations.”
A BASF survey showed the overall herbicide treated area decreased by 67% in autumn 2012 through to January – largely a consequence of wet weather.
This heaped more pressure on ailing sulfonylurea post-emergence options, such as Atlantis, and evidence of poor control is easy to find this summer.
“Control with Atlantis is becoming a lottery across my area, so growers must get those pre-ems on at all costs,” adds Mr Robinson at a recent roundtable debate.
Stacking high
“Stacking” – or the combination of multiple active ingredients at pre- and peri-emergence – is the latest buzzword in the quest to beat blackgrass.
Association of Independent Crop Consultants (AICC) agronomist and trials chairman Mike Thompson has been looking at how far stacking can be pushed and has shown that each new addition gives improved blackgrass control.
“In 2012 AICC trials, stacking six actives at full label rate has achieved blackgrass control of 96% on ground with heavy blackgrass infestation,” says Mr Thompson.
However, he was quick to point out that this may not be sustainable both economically and with regards to crop safety, despite seeing no ill effects in his trials.
Growers can use heavy stacks, but at their own risk as manufacturers will not support them if there is significant damage to the crop, so they should consult their agronomist.
“We also showed that there was a slight drop in control when applying at peri-emergence, but that was in ideal conditions with soil moisture,” he adds.
Both agreed that the best pre-emegence stack was to use Crystal + Hurricane + Defy, as it has been the most consistent performer over a number of years.
Adding Avadex
Avadex should also be an important part of the pre- or peri-emergence stack where growers have access to an applicator or it can be use in suspension with liquid fertiliser.
Midlands-based Indigro agronomist Damian McAuley says the product has a key role where early drillers have missed their stale seed-bed opportunities or conditions are dry.
“Avadex should also be applied straight after drilling and we have had some excellent results when followed up with a flufenacet-based spray,” says Mr McAuley.
Don’t forget the fundamentals
The three agronomists warned growers to remember the basics of cultivations and establishment to ease the pressure on the available herbicide chemistry.
A low blackgrass dormancy year should “dangle a carrot” to those thinking of drilling early, with a delayed drilling offering the opportunity to get the most out of a stale seed-bed.
Mr Robinson says to focus on bad fields first, get them cultivated early and allow time for germination.
“If the opportunity is missed, work on seed-bed quality to give the pre-ems the best chance and choose competitive varieties,” he adds.
Extreme blackgrass infestations may necessitate changes in cropping or fallows and Mr Thompson’s clients have had success with triticale and spring oats.
While Mr McAuley’s growers have conducted land swaps with livestock farmers or put blackgrass infested land into environmentally-friendly Entry Level Stewardship schemes.
