The Courier & Advertiser (Fife Edition)
Researchers find high levels of plant disease in Perth
Milder autumnal weather conditions have led to an increase in a disease that impacts upon Oilseed Rape crop yields.
A nationwide survey by plant breeder Limagrain has detected Turnip Yellows Virus (TuYV) from central Scotland to southern England, at levels that have exceeded all previous years.
The survey, which covered 14 UK sites, confirmed infections of as high as 100% in some areas, leading commentators to urge farmers to consider more disease resistant varieties of Oilseed.
The disease, carried by the peach potato aphid (Myzus persicae), can reduce crop yields by as much as 30%.
As part of the annual survey, random leaf samples were taken from oilseed rape varieties in each of collaborative firm Agrii’s trial sites across the UK and tested in Limagrain’s laboratories at Rothwell, in Lincolnshire.
“We know that levels of TuYV incidence are associated with the distribution of aphids in the autumn before,” said Dr Vasilis Gegas, senior oilseed rape breeder with Limagrain.
“Levels of aphids in the autumn of 2016 were at levels comparable to 2014, which was a high infection year, and this year again the link between high numbers of aphids in the autumn and corresponding levels of infections is clear.
“You would expect to see high levels of infection in the more traditional OSR growing regions – but even here levels of infection are higher than ever before – 100% of samples taken in Fincham, Kings Lynn were infected with TuYV, and 90% of samples taken from the Wool pit site in Suffolk were infected ,” Dr Gegas said.
“Most surprising of all was that 75% of leaf samples taken from the Balbeggie site in Perth were infected, and this is the first time that we have seen such high levels of infection in Scotland.”
Dr Gegas concluded: “It is clear from these results that TuYV is endemic in the UK OSR crop, irrespective of region and is directly linked to the autumn aphid migration.”
According to David Leaper, of Agrii, visual detection of TuVY remains a challenge, and subsequently yield losses can be attributed to alternative factors.
He said early symptoms include purpling of the leaves, interveinal yellowing and reddening of leaf margins, which can all be confused with other stress symptoms and nutritional deficiencies.
“With the loss of neonicotinoid seed treatments and a move to earlier drilling and increasing resistance to insecticides, control of aphids has become more and more difficult and subsequently aphid-borne diseases more prevalent,” Mr Leaper said.
“There is some good activity to be had from the new foliar insecticides, Biscaya (t hi ac lorp id) and Pl en um(pymetrozi ne ), however both of these have very limited persistence and it’s very difficult to optimise the timing of these with when the aphids migrating.”