United Kingdom
April 2020
Many UK growers are starting to see that Clearfield technology adds significant benefits to oilseed rape production over the expected better control of pernicious brassica weeds.
The Clearfield system of Imazamox herbicide and oilseed rape varieties resistant to it has made reliable control of problem weeds such as charlock, runch and hedge mustard a reality in recent years.
The system’s efficacy is such that even fields that have been out of production for many years due to large burdens of these weeds, can be made suitable for oilseed rape once more.
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.
The added flexibility Clearfield provides around early weed control strategies means the technology can also be used help fine-tune time of drilling and reduce competition during establishment.
The ability to control pernicious brassica weeds effectively has been a huge benefit to many growers. It’s also allowed many to adopt a cost-effective ‘wait and see’ strategy without frontloading costs at the start of the season.
As well as allowing better control of difficult weeds, the result for many has been better quality at harvest by reducing erucic acid levels.
Claims and rejections into the crush have clearly increased over the last two years and much of this is down to volunteer oilseed rape as well as weed contamination.
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.
High performing varieties
The DSV varieties Plurax and Phoenix have proved very popular in recent years by adding in vital Clearfield functionality whilst closing the yield gap between such varieties and the highest outright yielders on the RL.
Lat year, Plurax CL had the highest gross output and highest oil content of all the Clearfield varieties independently tested by NIAB and is one of the few varieties which has been tested across 7 sites over two years.
Plurax CL is tolerant to verticillium wilt and in NIAB trials has produced a very high seed yield and the highest oil content of 44.6%. It is quick to establish in the autumn putting down a robust rooting system.
Whist its stem stiffness and resistance to lodging are two of its key strengths, Plurax CL also has a strong agronomic package with a score of 7 for Light Leaf Spot and 6 for Stem Canker.
Phoenix CL is another high yielding Clearfield variety with an outstanding autumn vigour combined with a good seed yield of 106% and an oil content of 43.6%.
With benchmark agronomic features it has a 6s for both light leaf spot and stem canker resistance as well as enhanced pod shatter resistance for extra flexibility at harvest.
These highly successful varieties are now joined by Simplex CL which adds even better disease resistance properties alongside high outputs and yields.
Simplex CL lifts the bar higher still
Simplex CL combines RLM7+ Phoma Stem Canker resistance, pod shatter resistance and Clearfield technology.
With high levels of autumn vigour, the variety also grows away quickly in the spring with very good resistance to lodging compared to some of its competitor Clearfield varieties.
Simplex CL combines this with a superb agronomy package and is a good choice for drought conditions with its strong growth giving potential for compensatory growth with assimilation from its leaves and stems.
Offering medium maturity, Simplex CL has a stiff stem and high scores for disease with a 6 for light leaf spot and a 9 for stem canker. In recent trials, it has also performed well for Verticillium wilt resistance.
DSV’s breeders class it as a ‘stay green’ variety meaning where many varieties’ stems will discolour at maturity Simplex CL will stay green. It has also been noted as a variety which tolerates late frosts better than some other varieties.
Such developments will ensure Clearfield varieties remain popular and their uptake by growers who have both used the approach successfully in the past and those who are trying it for the first time, remains strong.
DSV already has a quad-layer Clearfield variety making its way through the UK testing system and this is likely to add even greater functionality and performance to the technology. Without doubt, Clearfield is here to stay.
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