Sugar beet growers will be able to choose virus yellows tolerant beet in 2022 after Maruscha KWS was added to the BBRO Recommended List.
Other notable additions from KWS include Katjana, a high-yielding BCN tolerant variety with low bolting, and Smart Rixta, a Conviso Smart variety that is a good partner for the well-established Smart Janninka.
In virus yellows trials in East Anglia over three years, Maruscha demonstrated tolerance to Beet Mild Yellowing Virus (BMYV) and a positive response to Beet Yellows Virus (BYV).
KWS says it has made developing tolerance to virus yellows a priority for the UK, which has among the highest seasonal risks of infection of any country in Europe.
Breeding varieties with strong tolerance remains a difficult and complicated process because of the different nature of the closterovirus and polerovirus strains that make up the virus yellows complex.
The polerovirus genus includes Turnip Yellows Virus (TuYV), which can cause yield losses of up to 30% in oilseed rape, and potato leaf roll virus, possibly the most important virus disease of potatoes.
The nature of the viruses involved means tolerance to one form of the virus does not necessarily confer equal protection against another, explains Ben Bishop, KWS country manager for sugar beet in the UK.
“Maruscha KWS is the first variety to come through the KWS breeding programme with a level of tolerance that supports commercially viable yields,” says Mr Bishop.
KWS will have a series of demonstration plots of Maruscha KWS in commercial crops of sugar beet in the 2021 season. Mr Bishop says this means interested growers will have the opportunity to see how the crop performs under real-world conditions this summer.
While its tolerance to virus yellows is likely to pique grower interest, Maruscha KWS has also demonstrated good disease resistance to the principal threats, rust and Cercospora leaf spot in list trials.