Many growers are already harnessing hybrid barley’s spring vigour, its ability to build canopy quickly and its complex plant architecture to smother out blackgrass.

However, independent research has now revealed the crop to be equally effective against other problematic grassweeds.

Trials by Agrii and Adas, in partnership with Syngenta, have shown that hybrid barley can reduce the populations of brome and ryegrass by almost 70%, and should therefore be a key element of any integrated weed strategy this coming season.

Brome

While blackgrass has been the focus in recent years, bromes are affecting growers across all cereal-growing regions in the UK.

“Sterile brome is public enemy number two,” says Paul Roche, seeds technical manager at Syngenta.

While the weed is more selective of soil type than blackgrass, he believes the uptake of direct drilling means the weed is set to become an increasing problem, as the seed is left on the surface. 

Traditionally found on headlands, brome tillers less than blackgrass in a crop, producing just one or two tillers compared with seven when growing on a headland without any competition.

However, each brome tiller produces between two and six times as many seeds as blackgrass, producing a huge seed return of 50-80 seeds per tiller compared with just 15-20 for blackgrass.

So how can farmers tackle the weed and reduce seed return?

One factor hampering efforts is the lack of up-to-date information on how to control the weed.

“Information on brome is limited. It was last looked at in the 1980s, but has largely been ignored since good control was being achieved by herbicides,” says Sarah Cook, Adas senior research consultant and weed specialist.

One area needing research is the potential role of hybrid barley, as some farmers had reported anecdotal success in controlling brome.

So, in 2018, Syngenta started to investigate the potential effectiveness of hybrid barley in stamping out the grassweed. 

The trial

Trials were carried out by Syngenta and Adas at two sites in Cambridgeshire to compare the competitiveness of hybrid barley against conventional two-row winter barley and winter wheat.

This was followed by another year of trials at different sites in Cambridgeshire and North Yorkshire.

Four years of data show that the population of brome in hybrid barley is 50% lower than it was in wheat, purely due to the competitive effect.

While two-row barley reduced the number quite well, the brome dragged the crop down, while the winter wheat was not able to be harvested.

Alongside a higher number of brome plants in the crop, growth analysis of the weeds when wheat was at growth stage 30 showed there was a higher incidence of brome, with two tillers per plant rather than one per plant.

These results are mirrored by those achieved by Agrii at a high-pressure site near Edinburgh, which again compared hybrid barley with conventional two-row barley and winter wheat, but also with six-row conventional winter barley.

At the high-pressure site, hybrid barley achieved 50-90% control, with the average being 69%.

As well as reducing the number of tillers on brome plants, the seed, as well as being fewer, is also less mature when compared to weed plants growing in wheat.

While both two-row and six-row conventional barley reduced the amount of seed produced compared to wheat, they did not give as good results as the hybrid barley.

Combining barley before wheat will also have a significant effect on the number of seeds that are allowed to reach full maturity before harvest.

While the reduction in weed numbers by hybrid barley is significant, it is not a magic bullet and must be used as part of an integrated strategy, stresses Dr Cook.

Effect of cultivation

The effect of cultivation on weed numbers was looked at in more detail at the trial in Edinburgh.

Situated on a real working farm, the site has a mixed population of both great and sterile brome, and a long history of direct drilling, meaning all seeds were towards the top of the soil profile.

Ploughing to invert the seed and burying them lower down the soil profile had a major impact on seed density, says Mr Roche.

“Brome numbers in the crop that had been direct drilled were like a forest, but there were only a few plants in the ploughed areas,” he says.

“It’s a quick and simple thing for growers to do, and the equipment is readily available.”