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 include KATJANA KWS, a high-yielding BCN tolerant variety with low bolting, and SMART RIXTA KWS, a CONVISO® SMART variety that is a good partner for the now well-established SMART JANNINKA KWS.
In virus yellows trials in East Anglia over three years, MARUSCHA KWS has demonstrated tolerance to Beet Mild Yellowing Virus (BMYV) as well as a positive response toBeet Yellows Virus (BYV). These two forms of the virus complex have been found to inflict losses per plant of up to 30% and 49% respectively.
KWS has made developing varieties with tolerance to virus yellows a breeding priority for the UK as it has one of 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 strains that make up the virus yellows complex.
BYV is a closterovirus while in contrast BMYV and a third form of the virus, Beet Chlorosis Virus (BChV), are poleroviruses. 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 distinct nature of the viruses involved means that 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. It has recorded minimal losses to BMYV infection and respectable losses with BYV compared to those seen in susceptible varieties,” says Mr Bishop.
“KWS will have a series of demonstration plots of MARUSCHA KWS in commercial crops of sugar beet in the 2021 season, so those interested will have the opportunity to see how the crop performs under real-world conditions this summer, coronavirus restrictions permitting,” adds Mr Bishop. Details will be available on the KWS website as dates are agreed.
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 (Uromyces betae) and Cercospora leaf spot (Cercospora beticola) in RL trials.
Good cultural measures
The introduction of varieties with tolerance to yellowing viruses represents an opportunity to protect yields but exploiting this possibility will also involve the continued use of cultural measures, such as good field hygiene.
“MARUSCHA KWS should not be thought of as the sole solution to virus yellows. Its tolerance, and that of other varieties as they are introduced will help to manage the risk but should be used alongside other measures such as controlling volunteers on spoil heaps as part of an integrated strategy. Good field hygiene is the basis to controlling virus and disease across all crops and this applies equally to beet,” says Mr Bishop.
New BCN tolerant variety
An adjusted yield of 102.7% of controls, means KATJANA KWS is another high-yielding variety with tolerance to beet cyst nematodes.
“KATJANA KWS is our highest-yielding BCN tolerant variety and with excellent low-bolting performance will appeal to those seeking to reduce their risk from this pest for which there are few conventional methods of control. We expect it to find interest among those with a history of BCN as well as those looking to protect the viability of land for the long-term,” says Mr Bishop.
New CONVISO® SMART variety extends choices
As growers ponder weed control strategies without desmedipham the appeal of the CONVISO® SMART system continues to grow.
“The addition of SMART RIXTA KWS to the BBRO RL marks the solid progress KWS is making in bringing varieties to market with tolerance to ALS herbicides. The first variety in this group, SMART JANNINKA KWS has been popular with growers in need of a simple approach to weed control. SMART RIXTA KWS is a good fit to this system with low bolting when sown in the main drilling window and an adjusted yield close to the average of control when grown under the CONVISO® SMART system,” says Mr Bishop.