As featured in Arable Farming Magazine

Hybrids well equipped to beat brome and ryegrass

by Arable Farming July 2020

The vigorous growth of hybrid barley, known for suppressing black-grass, could also be a useful tool in the fight against brome and ryegrass, according to research.

Earlier trial work has already shown hybrid barley to be more competitive against black-grass than both winter wheat and conventional two-row winter barley, says Syngenta hybrid barley portfolio manager Mark Bullen.

This was evidenced by clear reductions in the number of heads per black-grass plant and per sq.m in the hybrid compared with the other two crops, but also those black-grass heads that did survive in the hybrid crop contained fewer seeds. When combined together, these equated to a reduction in black-grass seed

return, he explains.

Trend

Now, newer trials are also revealing a similar trend against brome from hybrid barley, with further preliminary work also indicating competitive effects against ryegrass.

Mr Bullen says: There has been phenomenal growth in the over the last decade. Hybrid now accounts for about one-in-three fields of winter feed barley grown in the UK.

High yield is its biggest attraction, but there is no doubt growers have also been including it in rotations as part of a wider black-grass suppression strategy

The competitive effects of hybrid barley come from its hybrid vigour and the rapid growth phase it goes through in spring. This competes with black-grass tillers. However, its large root mass will also compete with black-grass for water and nutrients, and its dense canopy shades black-grass from sunlight.

On-farm observations over recent years had started to hint that hybrid barley may also have competitive effects against brome grass. So, beginning in the 2017/2018 season, we decided to put this to the test.

Working with ADAS at sites in Cambridgeshire and Yorkshire, Mr Bullen says trials over the next two seasons did indeed reveal a similar trend with clear reductions in brome heads in the hybrid compared with conventional two-row winter barley and winter wheat.

This was further backed up by brome work for Syngenta at an Agrii trial site near Edinburgh last season.

Conventional

This compared hybrid barley against winter wheat and conventional two-row winter barley, and also against a conventional six-row winter barley, Mr Bullen notes.

The Edinburgh work was part of a larger trial which also examined other factors, such as cultivation methods.

Results showed ploughing gave a massive reduction in the density of the brome population at the site compared with direct drilling. Based on this, results were examined from the direct-drilled area where the four different crops were put under high pressure from a brome population of 117-210 plants/sq.m.

Competitive

Assessments from the plots revealed the hybrid barley was more competitive than the conventional six-row barley, which in turn was more competitive than conventional two-row winter barley, which in turn was more competitive than the winter wheat.

While winter wheat was giving 10% brome suppression on average, and the conventional two-row and six-row winter barleys were giving 20% and 25% respectively, the brome suppression from the hybrid averaged a substantial 69%.

In addition, as well as fewer brome plants per sq.m in the hybrid barley, the brome plants which did survive also had fewer tillers and bore fewer seeds. This was a similar trend to the earlier work we had seen with black-grass, Mr Bullen adds.

Ryegrass results

In tandem with brome suppression trials, Syngenta undertook a preliminary trial looking at ryegrass suppression from hybrid barley last season, at its dedicated Ryegrass Focus site near Doncaster.

Assessing levels of ryegrass in plots of hybrid barley, winter wheat and conventional two-row winter barley, results showed that, compared with 328 ryegrass heads/sq.m in the wheat and 257/sq.m in the conventional winter barley, 114 ryegrass heads/sq.m were recorded in the hybrid.

Mr Bullen explains: We also found that, of those ryegrass heads that did survive in the hybrid barley, more of them were below the crop canopy, where they were found to have fewer florets and therefore fewer seeds.

Overall in the trial it was calculated that while conventional winter barley resulted in a 22% reduction in ryegrass seed return versus winter wheat, hybrid barley gave a 67% reduction.

The work also examined the effects of using hybrid barley in conjunction with a Defy-based pre-emergence herbicide stack. This combination further reduced populations down to just eight ryegrass heads/sq.m.

Clearly, these are early stage results and trials are ongoing.

Hybrid barley isnt a magic bullet against grass-weeds, but it could form part of an integrated approach to reduce populations.

Black-grass, brome and ryegrass are the ‘big three grass weed problems, and growers should remember bromes and ryegrass are even more competitive than black-grass.

Growth

In the case of black-grass, we have also found that using an early spring nitrogen application to boost growth of the hybrid increases its competitiveness, as too does sowing at a slightly higher seed rate, Mr Bullen concludes.