Hybrid barley spring vigour and ability to suppress black-grass makes it an essential tool in any growers’ long-term approach to controlling the problem, according to Scott Cockburn of Syngenta.
Speaking at a Syngenta Black-grass Focus Week demonstration in Oxfordshire last week (7 June 2016), he highlighted trials that showed hybrid barley, together with a pre-emergence herbicide stack, had suppressed black-grass heads from over 700 per m2, to less than 100 – equivalent to over 85% reduction.
The trials, under incredibly high black-grass pressure at the Syngenta Innovation Centre near Kiddlington, showed the Bazooka hybrid barley, sown at its standard recommended 200 seeds per m2, was over twice as effective as Gallant winter wheat sown at 400 seeds per m2 and three times better than the conventional barley, Glacier, also sown at 400 seeds.
All the trials received the same pre-emergence ‘stack’ herbicide treatment.
The hybrid barley even outperformed Gallant wheat sown at double-rate 800 seeds/m2 – with the implication that would have for cost, increased lodging risk and higher disease conditions.
"This work has clearly demonstrated the value of the spring hybrid vigour in suppressing black-grass seed head numbers from developing," reported Scott.
"The extra rooting, flag leaf size and crop height have all helped to reduce back-grass tillering and head numbers – as well as enhancing the crop’s productivity.
"Furthermore, each black-grass seed head - and individual seed - is physically smaller, which should help to reduce its viability and the risk from seed return," he added.
Scott pointed out a compilation of results from independent trials under high black-grass pressure had revealed that wheat crops returned an average 4509kg of black-grass seed per hectare, compared to 2060kg under conventional barley cropping, and a 85% reduction at just under 660kg/ha with hybrid barley.
"Growing hybrid barley is not going to eliminate the black-grass problem for growers," he advised, but it clearly has an important role in reducing the burden.
"As part of an integrated approach, alongside the herbicide programme, cultivation, drilling dates and cropping options, it has definite back-grass control benefits for the long-term rotation."
Reviewing black-grass herbicide options on the Oxfordshire site, Syngenta Field Technical Manager.
Iain Hamilton, demonstrated the advantages of pre-emergence stacking to increase control rates and minimise the seed return.
"The trials have shown that each individual component in a pre-emergence mix can offer an incremental advance for overall results, depending upon the season and the specific conditions," he advised.
"The challenge is to know which element to include or leave out, depending on the individual field’s back-grass population and the season.
"The one thing that we have seen, year on year, is that the inclusion of Defy in the mix is the one element that has always proved effective and given a positive increase in black-grass control."
Adding Defy to a flufenacet base treatment has consistently increased black-grass control by more than 20% over the past three year’s work at the Syngenta Innovation Centre on the farm.
It has given significantly better improvement compared to other options, such as flupyrsulfuron.
A pre-emergence stack of Defy plus, flufenacet/pendimethalin plus DFF and flupyrsulfuron, has delivered the best control in each of the past three seasons it has become the standard on the worst affected fields on the farm, topping 90% control in 2014/5 season.
"The actual levels of control delivered by the pre-emergence stack vary from year to year, which further highlights that herbicide performance is always dictated by the season and the field conditions," Iain reported.
"It also reinforces why growers and agronomists must adopt an approach that optimises performance though application best practice, and incorporates all the tools available to beat black-grass."
