The perfect storm for Turnip Yellows Virus infection

This autumn could see the perfect storm for Turnip Yellows Virus (TuYV) infection in early drilled oilseed rape crops warns plant breeders Limagrain UK.

“An early harvest and ideal drilling conditions has meant that many oilseed rape crops will be drilled over the next two weeks into near perfect conditions. Crops will therefore be quick to emerge and establish – and we could be looking at some fairly lush crops as we head into the autumn as a result,” says Les Daubney, oilseed rape product manager with Limagrain.

“When combined with the high aphid populations from the recent warm weather, we have the ideal conditions for infection of these early drilled lush crops from TuYV.”

“The timing of infection of TuYV from aphids has a significant influence on the levels of infection and subsequent yield – studies conducted by University of Warwick have confirmed that the earlier the infection the greater the yield loss,” he adds.

“With up to 72% of Myzus persicae carrying the virus – the levels of infection this season could be very high and we could be looking at yield losses of as much 30% as a result.”

“Whilst foliar insecticides can offer some solution to the aphid problem, there is widespread resistance to pyrethroids and primicarb to consider,” says Philip Marr, oilseed rape specialist with Agrii.

“Plenum is the best option going forward but it’s important to recognise that it can only offer control in the autumn for a limited period and with the drilling season looking so early – we could be facing a serious challenge from TuYV infection as the autumn progresses.

Variety choice

Variety choice will be even more critical than ever and may require a change in mind set where resistance and agronomics play an increasingly crucial role in order to protect yield, says Mr Daubney.

“To date oilseed rape variety choice has been very much centered around yield, however when looking at options for this coming season it’s important to remember that results from this year’s trials are based on those varieties being grown with a neonicotinoid seed treatment.”

“So the challenge this season is to select a variety based on its performance when grown without a neonicotinoid seed treatment.”

Limagrain has the only commercially available oilseed rape variety with resistance to TuYV on the market, Amalie, and seed stock is still available for this autumn, he says.

Amalie is a conventional OSR variety which has resistance to TuYV. “The variety has completed NL trials and will hopefully be considered for RL trials in 2014-15. In official HGCA trials using Cruiser treated seed, Amalie has a gross output similar to the widely grown variety, DK Cabernet.”

“However, our own trials using untreated seed over the last four years have clearly shown that where TuYV is present, the yield of Amalie is often up to 10% higher than non-resistant varieties.”

“It’s also important to note that the agronomic package of Amalie is on a par with Cabernet,” says Mr Daubney. “Earlier to flower and mature, Amalie is also shorter than Cabernet with better resistance ratings to light leaf spot and stem canker.”

“Amalie is also a slow developer which means that it will not get over lush going into the winter, making it more suitable for the early drilling slot.”

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