Rather than focusing on factors which can’t be controlled, what can growers do to proactively de-risk oilseed rape and up their chances of success at harvest? From establishment schemes to varietal choice, CPM explores the options.
“We estimate that roughly half the OSR crop area is in an establishment scheme of one form or another.” RODGER SHIRREFF
By Rob Jones and Janine Adamson
Such is the threat of cabbage stem flea beetle and winter stem weevil and the difficulties with which they can be controlled, that for many UK growers, oilseed rape has become a high-risk crop. Arguably, this is best demonstrated through the gradual decline in cropping area which for Harvest 25, is estimated to be less than 250,000ha.
In recognition of the difficulties growers face when it comes to insect pest control, plant breeders and seed merchants have introduced risk sharing schemes as well as conducted work to identify the cultural measures which could support establishment.
As such, establishment schemes – whereby the grower is reimbursed either fully or partially for the cost of the seed – have proven so popular that around half of the 2025 OSR area is thought to be in a scheme of one form or another.
Similarly, research into the factors influencing establishment has led to the wider use of companion crops, improved nutrition and variety selection, to the benefit of the grower.
According to Agrii’s national seed business manager, Rodger Shirreff, OSR has long been a challenge to establish well, but it was the burden of CSFB that raised the stakes. “OSR has always suffered from pest attack and difficulties in establishment, but growers had the tools and experience to cope.
“The loss of neonicotinoid seed treatments, however, changed the economics of production to such an extent that the only way to maintain interest in the crop was for others to adopt a share of the risk. In fact, we estimate that roughly half the crop area is in a scheme of one form or another,” he explains.
Schemes vary in the extent of their support and the criteria under which they can be invoked, but the principle is much the same, adds Rodger. Importantly, crop failure isn’t defined as ‘by pest attack’, but can be as a result of flooding or even excessive grassweed competition.
“Terms vary, but in general, a scheme has to be requested at the time of ordering; seed should be sown by 20 September and, in the event of a crop failure, a claim with proof of establishment and subsequent failure submitted by the end of October,” he says.
CRITERIA
Schemes are often variety dependant and not all varieties are underwritten to the same extent, warns Rodger. “Some varieties are backed with a credit note for the full invoice amount, others with a credit note for a set amount and others with the offer of free replacement seed for re-drilling.
“The Agrii premium scheme offers a full money back guarantee for seed bought at the full retail price regardless of the reason for failure. Choosing which scheme best meets your requirements comes down to attitude to risk and which variety best suits the situation,” he suggests.
David Leaper, Agrii’s seed technical manager, believes establishment schemes have helped to sustain interest in OSR while trials have sought to identify which varieties best meet a grower’s situation by investigating different establishment regimes.
“Our experience is that where the crop establishes well, it’ll go on to perform well, but variety choice is key to overcoming CSFB issues,” he points out.
David highlights the success of grower guides in helping farmers to adapt to the threat of larvae damage. “In 2023, just 10% of the OSR area sown with Agrii seed was the subject of a claim, and in 2024, it was significantly less. A direct result of these schemes is the de-risking of the crop, but an indirect result is that growers have become better at establishment.”
RISK AVOIDANCE
A consequence of this risk-averse attitude is a reluctance to experiment with new varieties, he believes, with growers instead choosing to remain with those which have performed well in the past.
“Reliability is a big factor for growers. DK Exsteel, for example, is now in its seventh year and was Agrii’s second best-selling variety in 2024. It’s been technically surpassed by varieties with TuYV resistance but is still one of the highest yielding varieties on farm,” he says.
This season, Agrii is introducing Recommended List candidate DK Exedge as a potential successor to DK Exsteel. “DK Exedge has looked exciting in our trials during the past two years – it has the vigorous spring regrowth that we look for to grow away from larval damage,” adds David.
Despite this year’s OSR area looking full of potential for many, it’s last chance saloon for the crop at Riggall’s Farm near Boston, according to cousins Charles and Philip Roberts.
While they admit the farm’s 35ha of DK Exteel looks superb and with plenty of potential, their caution follows two years of heavy crop losses due to CSFB damage. “We’d been growing OSR pretty successfully for a number of years with the Dekalb Ex hybrid varieties, says Charles.
“We liked them because they were pod-shatter resistant, relatively compact and consistent. But as soon as neonicotinoid seed treatments were banned we started to struggle with CSFB. Although we had a year or two where it wasn’t too bad, the past couple of years have been a complete disaster,” he adds.
Historically, OSR has been an important break crop on the farm, highlights Philip. “This is a heavy land farm – wheat is our number one crop and OSR has been our number one break crop, but it now has a question mark over it.
“But we’re very limited for break crops. During the past 25 years OSR has become very important for us and if we lose it, it’ll leave a massive hole.”
Late last summer, the cousins agreed to give it ‘one last roll of the dice’, drilling what might potentially be their last crop between 6 and 10 September. The deciding factor was Agrii’s establishment support scheme, under which DK Exsteel is among the varieties supported, along with backing from Bayer.
“There’s a fine margin between winning and losing. The establishment scheme made the difference this season because if the OSR had failed, we knew we could recoup the cost of the seed,” concludes Charles.
KWS UK’s product manager for oilseed rape, oats, peas and rye, Rory Hannam, understands that OSR remains one of the most scrutinised crops on the farm. With this in mind, he says building resilience into the crop starts with matching a variety to its proposed location, where growers focus on taking advantage of the latest breeding developments to allow crops to reach their full potential.
“In many ways, the success of an OSR crop is decided before the drill even hits the field. Variety choice has always mattered but it’s becoming pivotal to managing OSR risks and delivering performance,” he continues.
Rory believes there are five essential characteristics to look for when selecting a variety and deciding on the right management approach – all traits which align closely with the realities of growing OSR in today’s conditions.
First and foremost, he cites autumn vigour as critical, particularly when drilling later in the season to avoid CSFB migration, or on areas known to have the highest incidence of the problem. “A fast-developing variety that can push through the cotyledon stage and put down roots quickly and build biomass, gives the crop the best possible head start,” he explains.
“In fields where drilling is in late August or into September, we require a variety that gets out of the ground quickly to help survive potentially tough conditions. That early vigour isn’t just about beating CSFB. It’s also about reducing herbicide reliance, competing with weeds and compensating for early pest damage.”
At the other end of the season, harvest security becomes the focus – with more frequent and unpredictable weather events in July and August, pod shatter varietal resistance has evolved from a ‘nice to have’ into a ‘must have’, he believes.
“Pod shatter resistance is an absolute necessity. It only takes one thunderstorm or a few days’ delay with the combine to knock serious yield off the crop if pods are brittle and over-mature. Modern hybrid varieties with robust pod integrity also allow greater flexibility around harvest preparation and timing – a key advantage for busy arable businesses with large areas to cut.”
A third trait climbing the priority list is resistance to turnip yellows virus (TuYV), a potentially devastating virus spread by peach-potato aphids. “As control options dwindle and resistance to insecticides becomes more widespread, the ability to safeguard OSR crops against TuYV via genetics is increasingly attractive.
“We’re seeing aphid resistance to pyrethroids and growers choosing to not apply these to crops to enhance the pest’s natural predators. At the same time, the window for insecticide applications is getting tighter, so it’s not advisable to assume we can spray our way out of trouble,” he stresses.
“Choosing a variety with TuYV-resistance is a key option in any integrated pest management plan to help mitigate the virus.”
MIGRATING DISEASE
Light Leaf Spot (LLS) has traditionally been associated with wetter, cooler conditions in the North but that’s no longer the case, highlights Rory. “During the past five years, LLS has become more widespread and we’re picking it up regularly in OSR across the Midlands and Southern Counties.
“It’s a disease which can have a significant impact on canopy development and ultimately yields. Building a strong resistance score to LLS into your variety choice criteria is now essential across the board.”
Finally, structural strength is a trait that often flies under the radar until OSR crops begin to lodge, he points out. “As plant biomass increases through the spring and into flowering, stems have to be able to carry that weight without collapsing.
“There’s been a lot of progress in seed breeding to improve stem stiffness and lodging resistance in OSR, but it should still be a key consideration for variety selection especially in fertile soils or with high nitrogen regimes. A well-structured plant is easier to manage and able to make the most of its potential right through to harvest,” comments Rory.
For Oxfordshire grower David Passmore, the value of these five traits became clear in his first season growing a commercial hybrid OSR crop.“Hinsta (KWS) is showing real promise as a standout hybrid variety for us. All of the traits we look for play to Hinsta’s strengths, and it really is shaping up to fit our system well,” he says.
Drilled in early September into wheat stubble using a subsoiler, David applied digestate at establishment and hoped for a clean start – something he says the crop delivered. “It established cleanly, showed no sign of disease, and the canopy is exactly how I wanted it – not too thick, but full of potential.
“Even after a challenging start to the season, the crop has come through really well. It’s the kind of variety that doesn’t race away too quickly, which is exactly what I’m looking for,” he adds.
According to David, this balance of steady growth and strong early vigour proved ideal for the farm’s rotational timings. “This is our first time growing hybrid OSR as a commercial crop rather than for seed, and based on Hinsta’s performance, we’ll definitely keep OSR as part of our wider rotation. It’s proven it can handle pressure and still deliver.”
This article was taken from the latest issue of CPM. Read the article in full here.
For more articles like this, subscribe here.
Sign up for Crop Production Magazine’s FREE e-newsletter here.
