A mild autumn and winter combined with a build-up in aphid numbers since the loss of neonicotinoid seed treatments has resulted in the highest level of Turnip Yellows infection ever seen in the UK this year.
The average rate of infection this spring was 84%, compared to just 49% last year, however, more worryingly still the virus is showing high levels in areas not traditionally seen as hotspots.
Limagrain’s annual TuYV survey reveals the virus, which is spread by the peach potato aphid and is largely symptomless in oilseed rape crops, is being seen in increasing levels in the North, and is also starting to be seen in the West.
“We are seeing 60% infection rates in Aberdeen, which is very northern for the virus, and while we used to see an infection rate of 10% in Cornwall, now it is much higher,” says Vasilis Gegas, Limagrain’s European portfolio manager for oilseed rape.
This has been reflected in the Agriculture and Horticulture Development Board’s Recommended List trial harvest results, which show that TuYV-resistant variety Aspire was top yielding at the trial sites in Herefordshire, Kent and Northumberland.
Although a harsh autumn and winter could control aphid numbers, the longer the industry is without effective chemistry the more the virus is being allowed to build up, warns Mr Gegas, and an early infection has more impact on yields.
This is particularly pertinent this season as growers in the East are already drilling their OSR crops for the coming season as conditions are now excellent.
“The earlier you drill, the better the conditions for aphids, it really opens the crop up to TuYV infection.
“My advice to growers is go when the soil conditions are right for the best chance for the crop to establish well and come through flea beetle, and that’s now,” said Mr Gegas.
“That’s why the genetics for TuYV-resistance are there, and growers in East Anglia and Cambridge should take advantage of this.”