Saturday, November 28, 2020

Winter wheat performance varies as growers battle blackgrass

December 21, 2017 by  
Filed under Crops

Farmers are experiencing greater variability in winter wheat yields as they employ increasingly sophisticated strategies to combat blackgrass.

Average winter wheat yields have slowly climbed since Strutt & Parker began its annual harvest survey 19 years ago – but growers are now seeing a wider range from year to year with greater variability over the past decade than in the previous five years.

George Badger, farm consultant and agronomist in Strutt & Parker’s Cambridge office, says: “Up until 2008 you can see that yields were relatively consistent year on year, but afterwards the variability seems to be a lot higher.”

Mr Badger believes this is partly due to blackgrass strategies rather than simply the weather. “While the low of 2012 and the highs of 2014 and 2015 are a lot to do with the fortunes of rainfall and sunshine, we think there is another factor at play.”

Later drilling

The survey covers mainly East Anglia and the Midlands where blackgrass is an issue. “It is our belief that part of the explanation is a shift to later drilling, as part of a strategy to tackle blackgrass once resistance to contact post-emergence herbicides became more evident from 2010 onwards.

“Late drilling is an essential grass weed management tool, but it does result in smaller root structures which leave crops more vulnerable to weather extremes than they were when people could reliably drill in September.”

Some 58,000ha were covered by this year’s survey. Mr Badger stressed that delayed drilling (after 15 October) remained the right course of action on the worst-affected fields, as it gave growers the best chance of both cultural and chemical weed control.

But the data showed how important it was for farmers to make their decision on a field-by-field basis rather than a whole-farm basis. This would help to ensure that drilling took place earlier in those fields suited to it, said Mr Badger.

Moisture critical

Attention to detail was crucial, he added. The most important factor in determining control with pre-or post-emergence residual sprays was access to moisture, so getting the benefits of autumn rainfall was critical.

An earlier-drilled crop – treated with a well-timed pre-emergence application when there is moisture available – could be better than a later-drilled crop with a pre-emergence application which remains dry in poorer seedbed conditions.

Mr Badger said: “In 2017, people who late-drilled second wheats were caught by the dry conditions and lost secondary tillers to the spring drought. This meant that crops of 6-7t/ha were quite common in the survey.”