Updated: Aug 27, 2020
RAGT Seeds has launched a guide to help growers get the best out of RGT Wolverine, Europe’s first BYDV-resistant winter wheat.
This very high yielding Group 4 wheat is available in limited quantities for sowing this autumn.
Farmers growing RGT Wolverine will gain season-long protection against BYDV, greatly simplifying their crop management by reducing the need to monitor and control aphid populations and benefiting the environment, says Tom Dummett, cereal and OSR product manager for RAGT Seeds.
One key piece of advice in the new guide is to use a single insecticide spray in the autumn on early sown crops to help protect the longevity of the Bdv2 trait which confers the resistance.
“This might seem an unusual recommendation given that we know RGT Wolverine is resistant to BYDV,” says Tom.
“However, resistance is not the same as immunity and, under very high-pressure scenarios, trace symptoms can be occasionally observed in lines that possess the Bdv2 trait.
“That said, the amount of virus is far lower than would occur with susceptible varieties. The advice to apply one insecticide is simply good stewardship to help protect the trait, which we believe will be invaluable to growers in the future.
“I would emphasise that after prolonged commercial use in Australia, the Bdv2 trait has shown no signs of breaking down to the virus. Two CSIRO varieties that contain it, Manning and Mackellar, the latter introduced 17 years ago, have maintained significantly higher yields when BYDV pressure is high, outperforming all other varieties in this situation.”
The reliability of RGT Wolverine and other Bdv2 lines was clearly demonstrated in high-pressure field trials at RAGT’s headquarters at Ickleton, Cambridgeshire, this season, confirming earlier findings from a range of laboratory and field experiments.
The Bdv2 lines, along with 10 popular Recommended List varieties, were sown on 17 September. Plots were inoculated eight times with infected aphids between early October and the end of April. Half the trial also received a single insecticide on 16 October.
Each plot was assessed weekly for BYDV symptoms starting from mid April to mid June. Scores ranged from zero (no signs) to five (very obvious symptoms and multiple stunted sites).
“In the plots with no insecticide, RGT Wolverine and the other Bdv2 lines showed only trace symptoms of the disease and no stunting was observed,” says Tom.
“By contrast, the 10 RL varieties in the trial were all affected by the disease, particularly when early sown. Symptoms ranged from a few yellow and red leaved plants to multiple stunted areas with severe leaf loss.”
The onset of these symptoms was delayed in the insecticide-treated plots and their severity was generally reduced, although some varieties still went on to display very obvious symptoms by early summer.
The overall mean symptom scores for each variety are shown in the graph below. “The results clearly demonstrate the effectiveness of the Bdv2 resistance gene in our BYDV-resistant material,” says Tom.
“This was confirmed by the percentage difference in plot yields between untreated and insecticide-treated plots. Eight of the 10 RL varieties yielded between 5% and 18% less when left untreated, whereas none of the Bdv2 lines lost yield.
“Growers who choose RGT Wolverine will finally be able to put the worries of BYDV behind them. They will also benefit from the variety’s very high yield, which can compete with the best on the RL whether the virus is present or not, and its good agronomic features.”
Further agronomy information:
RGT Wolverine is a relatively slow-developing variety in the autumn which makes it suitable for early sowing.
· The seed rates above assume good seedbed conditions and good moisture. Increase seed rates if seedbeds are poor, in blackgrass situations or if there is a high slug population.
· RGT Wolverine has a semi-prostrate growth habit during the autumn and is medium to high tillering.
· For early drilled crops a T0 would be advised
· RGT Wolverine is reasonably tall but responds well to PGR.