GROWERS have been warned that this autumn could be ideal for Turnip Yellow Virus (TuYV) infection in early-drilled oilseed rape crops.

Les Daubney, oilseed rape production manager with Limagrain UK, said an early harvest and ideal drilling conditions meant many oilseed rape crops would be drilled into near perfect conditions.

Crops will be quick to emerge and establish, and there could be some fairly lush crops heading into the autumn.

Mr Daubney said: “When combined with the high aphid populations from the recent warm weather, we have the ideal conditions for infection of these earlydrilled 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.

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

Philip Marr, Agrii oilseed rape specialist, said that while foliar insecticides could offer some solution to the aphid problem, there was widespread resistance to pyrethroids and primicarb to consider.

“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,” he said.

“With the drilling season looking so early, we could be facing a serious challenge from TuYV infection as the autumn progresses.”

Mr Daubney said variety choice would be more critical than ever.

“To date, oilseed rape variety choice has been very much centered around yield,” he said.

“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.

“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.

Mr Daubney said: “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 past four years have clearly shown that where TuYV is present, the yield of Amalie is often up to ten per cent higher than non-resistant varieties.”