Oilseed rape crops in parts of England are seeing rates of turnip yellows virus (TuYV) infection as high as 80% this season, according to early results from a nationwide study.
The virus is spread by aphids and is estimated to cost the industry £100m/year, with up to 26% loss in yield.
So far the survey has found that the highest rate of TuYV infection in OSR crops is in the south of England.
John Walsh of Warwick University is leading the research for OSR breeder Limagrain UK which, when completed in late May, will give a detailed picture of TuVY hotspots across the country.
“Overall results so far are showing generally high levels of infection across the three regions that have been tested as part of a project led by Dr Walsh,” said Vasilis Gegas, senior oilseed rape breeder with Limagrain.
“Results from the south of England have detected incidences as high as 80%, in Somerset incidences of up to 74% and in Yorkshire incidences of up to 72%, whereas in Cardiganshire we found incidences of up to 46%,” he added.
Dr Walsh blames the large numbers of aphids flying last autumn and a lack of neonicotinoid seed treatments for the high levels of cases this year.
Early signs of TuYV are purpling of the leaves and later symptoms of interveinal yellowing and reddening of leaf margins are not usually shown before stem extension and can easily be confused with other nutritional deficiencies.
The full and final survey results will be announced at the Cereals event in June.