New benchmark for OSR yields backed up with TUYV resistance

At the very top of the AHDB Oilseed Rape Recommended List for 2019/20, sits a variety with a UK gross output of 104% over control, Aspire

This conventional winter oilseed rape takes the leading position as the variety with the highest gross output on both the east, west, and northern list, based on its seed yield of 10% and its very high oil content of 45.8%. However, what is so exciting about Aspire is that it also offers Turnip Yellows Virus (TuYV) resistance – the first time that a Recommended variety has been able to offer both high yields and TuYV resistance.

Predominantly carried and spread by the peach potato aphid (Myzus persicae), the presence of TuYV in crops can be betrayed by a number of symptoms.

This includes reddening of leaf margins, purple colouring of leaf margins and interveinal yellowing and reddening. But it is often symptomless.

Under very severe infection, TuYV can cause stunting of the plants, resulting in up to 30% yield loss and is estimated to cost the industry between £67m-£180m each year. However, at lower levels most goes undetected.

University of Warwick’s John Walsh says TuYV is a “hidden problem”, with growers often unaware that crops are infected, as it occurs across fields and is often wrongly attributed to problems such as nutrient deficiency.

The first TuYV resistant conventional variety, Amalie gained its full recommendation back in 2017 as a special category but, Amalie’s yields did not match up to any of the non-resistant varieties.

“When we started working with traits such as TuYV there was a trade-off – essentially, they were suppressing yield, says Vasilis Gegas, Limagrain’s OSR European portfolio manager.

“But we have worked really hard to address this and within five years, we have moved from the bottom of the list with a TuYV resistant variety, to the top by a country mile,” explains Dr. Gegas.

“Every year we run a national TuYV survey with a range of industry partners; we test oilseed rape leaves from selected sites and the final results of this will be available mid-May. However, all the signs are looking like this year could be a potentially high TuYV infection year, as the mild autumn meant that aphid numbers were high.

David Leaper, Agrii’s OSR specialist, has monitored the levels of TuYV infection in the Agrii national trials network in collaboration with Limagrain.

“Over the past two years across 12 sites, TuYV infection was detected at levels ranging from 20%-95% – which shows that TuYV is clearly endemic across the whole OSR acreage.”

Levels of TuYV infection were higher in 2017 compared with 2018, but it’s key to note that in both years the levels were linked to aphid activity in the autumn, he adds.

“In last year’s trials which were taken to yield, Aspire performed at 104% of controls, which is in line with its Recommended List performance.”

“However, on half of the sites where the incidence of the virus was above 50%, Aspire’s yields increased to 111% of the controls, suggesting that the TuYV trait delivers roughly a 6% lift in yield.”

Although responses will differ every year depending on the level of infection, he notes.

When growers are looking closely at varieties, it makes sense to take advantage of genetic traits like TuYV that protect yield and bring the unit cost of production down, he says.

“At the end of the day buying a variety with traits is no more expensive than one that doesn’t have as many”

Aspire also comes with an excellent agronomic package; in the field, it’s not too tall, in fact, it is the shortest variety available on the AHDB RL with a stem stiffness rating of 9.

With good all round disease resistance, a 7 for light leaf spot resistance and a 6 for phoma and good tolerance of Verticillium wilt, it makes it the first choice variety for early drilling.

OSR Candidates breaking the yield barrier

Limagrain has two very high yielding hybrid candidates that are setting a new benchmark for OSR performance in the UK, whilst also offering resistance to TuYV and pod shatter.