Second generation Clearfield oilseed rape varieties will allow growers to reap far greater benefits than just better weed control, says breeder DSV.
The Clearfield area increased to 80,000ha in 2018 representing 13 per cent of the total oilseed rape area drilled with improved genetic resilience and yield improvements likely to take that even higher in the future, believes the company’s Michael Farr.
“In the early days, much of the interest in Clearfield was created by weed control with imazamox delivering reliable control of problem weeds such as charlock, runch and hedgemustard.
“Furthermore, many growers had identified the high cost of pre-emergence weed control from metazachlor-based products as being one of the most expensive elements of their establishment management.”
But in the post neonicotinoid era, crop establishment has been less of a certainty and growers have seen significant other benefits with Clearfield, he says.
“Many have found that by drilling a Clearfield variety they have more options in terms of drilling and subsequent agronomic strategies. From DSV’s own work on-farm we know many producers completely skip a herbicide application and many use other options later on in the season depending on the emerging weed burden.”
Better control of volunteers and improved quality at harvest is another factor that could lie behind the rapid rise in Clearfield popularity, he suggests. “Claims and rejections into the crush have clearly increased over the past two years and the main findings of research into this point towards volunteer oilseed rape being a major part of the problem.
“Clearfield is the perfect solution to such issues with one application of the chemistry giving significant control of volunteers resulting in an almost instant improvement in quality.”
Companion cropping is also increasingly popular, he says.
“Many growers believe these can confuse cabbage stem flea beetle giving them other feeding opportunities than just the oilseed rape and Clearfield varieties fit in perfectly with this approach.
“Mustard and other species drilled with Clearfield varieties put a barrier in the crop to give flea beetle other options for feeding, thereby relieving the pressure on the oilseed rape.”
More to come
On-going breeding development means Clearfield will offer even greater benefits in the future, Michael Farr believes.
“The first wave of Clearfield varieties were somewhat off the pace in terms of gross output and were not the best adapted for UK growing conditions, either.
“That’s all changed now with high yielding varieties featuring highly beneficial traits like pod shatter and tolerance to verticilium wilt.”
The latest Clearfield winter oilseed rape variety released by DSV, Plurax CL, is a great example of this, he points out.
“Plurax CL is a very well balanced variety with a unique combination of yield-stabilising factors including a good package of disease resistance including excellent resistances and tolerances against stem canker, light leaf spot and verticillium wilt.
“It has also shown a very high level of winter hardiness in a range of trials, delivering high yields and oil contents from a simple management system without the need for extensive agronomic intervention.”
One of the few varieties to be tested by NIAB across seven sites over two years in the UK, Plurax CL has delivered the highest gross output and highest oil content of all Clearfield varieties in the data set, he explains.
“It’s also been grown across Europe in all conditions and proven to be quick to establish in the autumn putting down a robust rooting system with exceptional stem stiffness and resistance to lodging.”
Another good example of a ‘second generation’ Clearfield variety proving itself in challenging conditions across Europe is Phoenix CL, Michael Farr adds.
“Phoenix CL is a benchmark for Clearfield performance across Europe being one of the first such varieties to reach the yield levels of normal hybrids.
“It is now one of the best adapted varieties available, consistently delivering high yield performance in a range of very difficult conditions with its yield stability underpinned by early vigour and a deep taproot system.
“This allows the variety to access water and nutrients in deeper soil layers, so as well as good establishment it has the ability to recover quickly in the spring after a challenging winter.
“Furthermore, it has a good package of disease resistance and exceptional pod shatter resistance that protects the seed through the full growing season giving it outstanding protection from sowing to harvest.”
Such varieties will drive growing acceptance of Clearfield as a production system of choice that can deliver benefits far greater than just better weed control, he says.
“There’s a lot more in the pipeline too with the next wave of varieties offering even greater agronomic features, better resilience for UK conditions and, of course, higher yields and oil contents.”