Drilling spring barley© Tim Scrivener

Farmers are losing more than 2t/ha of wheat by tolerating high levels of blackgrass rather than opting for spring crops, according to a survey.

Carried out by GFK on behalf of Syngenta, the survey found nearly 60% of the 200 growers with existing blackgrass problems said its severity had increased over the past five years.

See also: Switch to spring cropping to get on top of blackgrass

“The average control was 83% and worryingly, they were happy with that,” says Jason Tatnell, technical cereal herbicide manager at Syngenta.

“But you need a much higher control of 97% before you start having an impact on the weed bank.”

He believes farmers are becoming accustomed to high concentrations. “But leaving 17% of a high population, say 500 plants/sq m, behind is a lot of plants and you will see an impact on yield.

“Industry data shows just having 12 plants/sq m results in a 5% yield loss,” he explains.

One proven way to tackle resistant blackgrass infestations is by introducing a spring crop into the rotation and the respondents recognised the benefits.

“Industry data shows just having
12 plants/sq m results in a 5% yield loss.”
Jason Tatnell, Syngenta

“A quarter said they would grow spring barley if losses reached 2.5t/ha, but they were already losing an average of 2.2t/ha,” says Mr Tatnell.

Similarly, most said they would look to alternative approaches once herbicide expenditure exceeded £94/ha, although 21% were already spending over £91/ha.

But despite being at or close to the tipping point, many were still sticking with winter cropping.


He believes this inertia is due to fears over the viability of spring crops, with 30% saying they were unconvinced at the profitability of spring crops.

However, Mr Tatnell says if farmers delve deeper into the figures, “there is more cause for hope.”

Many are probably comparing margins of winter wheat with spring crops, assuming a wheat yield of 10t/ha. But with a severe blackgrass population you may be losing 2t/ha, so it is more realistic to compare with 8t/ha.

Inputs are lower for spring crops requiring less fertiliser and sprays and, therefore, the yield needed to make it pay is lower.

“There is also the yield gain in subsequent crops and if you do a good job in reducing populations, you could see wheat back up to 10t/ha.”

A similar proportion (28%) also felt their soil was unsuitable.

“The difficult, wet 2012-13 winter forced many to abandon drilling winter crops and drill spring crops instead. “We saw an extra 300,000ha of spring barley and some of this was successfully grown on heavy land.

“It can be done by being proactive and selecting the right variety that can be drilled later.

There is a mindset that barley is drilled mainly in January, but March can be as good for yield and getting on land easier, he says.

Nitrogen concerns

Where farmers do opt to grow spring malting barley, they may have concerns about meeting grain nitrogen specifications.

Syngenta barley campaign manager, Mark Britton, suggests selecting varieties for markets with a higher level of N acceptability, rather than growing for low grain N distilling.

“Propino is one example that provides some degree of risk management,” he says. “It’s a brewing variety with export demand, so is going into markets that will accept higher grain N levels.” 

Alternatively, if farmers are still concerned about meeting malting spec, then go for out-and-out yield.

“Look across the whole HGCA Recommended List. Some malting varieties are higher yielding than some feed varieties,” he adds.