Resistance to light leaf spot and phoma stem canker are the key attractions of a new conventional OSR variety from KWS that has just completed its National List testing and will be available for sale this autumn.
By Tom Allen-Stevens
A new conventional oilseed rape variety has been launched that promises consistent high yields and strong resistance to both light leaf spot and stem canker.
Butterfly from KWS completed its National List testing on Weds, 19 April. A candidate variety in AHDB Recommended List trials, it’s come through the two NL years with a yield score of 106%, and a 7 for both light leaf spot and stem canker resistance. (Full details and scores at http://www.kws-uk.com/butterflycpm)
Miss a spray timing during the season and you lose far more yield on a susceptible variety compared with one with a good LLS resistance rating, notes Carl Gibbard.
“It’s a variety with twin 7s for LLS and phoma, so the decision to put it forward as a candidate variety was straightforward,” notes KWS OSR breeder Carl Gibbard.
Butterfly has UK-wide suitability, says KWS OSR specialist Tom Dummett. “It combines high yields with excellent standing and stem stiffness with outstanding LLS and phoma stem canker resistance.”
The variety is available for autumn 2017 planting through Openfield and Agrii. “For us, the LLS resistance was the key, but this is backed up by a good stem canker score,” says Agrii’s Barry Barker.
“It doesn’t have the highest gross output of the candidates, but it’s in the ball park. Its performance has been consistent across two years of NL trials, however, and that’s significant.”
It’s not too tall, with a good standing ability, he adds.
Butterfly is slow developing, so can be drilled early, says Barry Barker.
Butterfly is a mid-flowering, mid-maturity variety. “It’s slow developing, so can be drilled early,” adds Barry Barker.
The importance of good LLS resistance shouldn’t be underestimated, stresses Carl Gibbard. “Miss a spray timing during the season and you lose far more yield on a susceptible variety compared with one with a good LLS resistance rating.”
This has been confirmed in trials carried out by KWS – there’s more information on the company’s website
Research work underway
KWS has been working on a number of related industry-funded projects with Prof Bruce Fitt and colleagues at the University of Hertfordshire.
Projects underway include analysis of quantitative disease resistance in OSR pathogens, and one that investigates an integrated strategy to control phoma pathogens.
“A lot of work has been carried out on Leptosphaeria maculans – the pathogen that is most easily identified from the spots on the leaf surface and causes stem base canker. But in some years, L. biglobosa – responsible for lesions on the upper stem and which appear more mottled in colour on the leaf surface – appears to be predominant. This is a pathogen we know relatively little about,” points out Bruce Fitt.
“We have varieties with good resistance to phoma, but pathogens always change, so we need to keep our eyes open.”
More detailed work on the genes in OSR cultivars that provide resistance to LLS is being carried out by PhD student Chinthani Karandeni Dewage.
Chinthani Karandeni Dewage (left) and Bruce Fitt are using genomics to gain a better understanding of resistance to LLS in OSR.
“Qualitative, or major gene resistance is easy to select, but it’s vulnerable to resistance breakdown as the pathogen may change. Quantitative resistance is polygenic, so more durable,” she explains.
“We’re using genomics to gain a better understanding of which locations in the OSR genome confer this with the aim of providing genetic markers to breeders.”
Much of the selection for cultivars with good disease resistance in OSR is done by visual assessment, notes Carl Gibbard.
“We’re moving away from relying on major gene resistance and are looking to stack genes which offer background resistance. Genomics will make my job so much easier.”
More information on Butterfly and LLS resistance can be found on the KWS website
