To get on top of black-grass, growers should work even closer with nature, according to the latest Nuffield arable scholar report.
This was a main conclusion of Ben Taylor-Davies’ 2016 Nuffield scholarship which investigated alternative solutions for the management of black-grass.
Supported by AHDB Cereals & Oilseeds and the Three Counties Agriculture Society, Ben explored approaches to weed control across the globe and used his experiences to suggest a new way of looking at rotations, based on five-year ‘blocks’.
Born on his family farm in Ross-on-Wye, Herefordshire, Ben joined agronomy firm Hutchinsons in the late 90s.
Ben said: “From day one, I loved the job of agronomist and it coincided with the real issues of black-grass herbicide resistance in Oxfordshire. This is where my passion for learning about this weed began to develop. Whatever we did, black-grass was always one step ahead. In many ways, you could describe it as the perfect weed.”
On a mission to learn from international experiences, Ben travelled the globe as part of his scholarship, landing in the USA, South Africa, Brazil, Argentina, Peru, China and Australia, as well taking in numerous stops across Europe.
Like all organisms, weeds can adapt to a changing environment. As black-grass plants produce many seeds each year, it makes them particularly adaptable – a key reason why multiple herbicide resistance has spread across so many UK farms.
But the weed is not only able to adapt to chemistry, it can adapt to shifts in cultural practices too.
Although around 80 per cent of black-grass emerges in the autumn, Ben says the move to later- and spring-drilled crops is selecting black-grass populations which emerge later and, given time, could erode the efficacy associated with today’s preferred cultural approaches.
In his report, however, Ben argues the weed’s capacity to adapt can be harnessed to fight black-grass in way that works with nature, rather than against it.
The trick, says Ben, is to use knowledge of black-grass selection when designing rotations, to encourage the weed population to find its niche in the system before making a radical change to it.
In particular, Ben says the following could be considered:
Within a field, rotate crops planted at similar timings with similar establishment methods in ‘blocks’.
Enhance black-grass selection
Use the same block for as long as possible (preferably five years) to enhance selection of black-grass populations which do well under the selected system.
Switch to a completely different block so the weeds that started to do well under the previous system become vulnerable.
Dr Paul Gosling, who manages weed research at AHDB, said: “Ben’s journey has been fascinating and his conclusions make interesting reading.
“AHDB supported this Nuffield Scholarship because it promised to look at weed control in a different way and it certainly has done that.
“Although science in this area is lacking, the idea that the selection of weeds can be directed by adopting a similar growing system for several years, then switching to a completely different system, has merit.
“Ben is convinced that over-reliance on any single system can increase weed management pressures and long-term solutions need to be built into rotations.”