Mild conditions during September and the start of October have led to unusually early and high incidences of Phoma leaf spots in Oilseed Rape and a high risk of Barley Yellow Dwarf virus seen in newly emerged crops across the country, warns national agronomic group ProCam Ltd.
According to the Group's technical director Dr. David Ellerton, disease pressure is now exceptionally high for the time of year, caused by higher than average autumn temperatures and recent wet weather.
"Growers need to be aware of the risk of Phoma in Oilseed Rape and any crops showing more than 10% leaf spotting should be treated as quickly as possible, as matters can quickly get out of control in these damp mild conditions.
"Crops in the South are particularly at risk although Phoma spotting is also being reported from the North of England. ProCam 4cast information shows a possible economic loss of up to £140/ha from Phoma over the last 5 years, so producers with affected crops must apply appropriate fungicide treatments as soon as they can."
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Cereal crops with more than 2 leaves per plant are at significant risk of BYDV and should also be treated as soon as possible with a suitable insecticide, Dr. Ellerton says.
"Coastal areas of the South, South East and South West are usually the most at risk to BYDV, but due to the mild conditions throughout the UK, growers across the country should now be vigilant. Reductions in yield and grain quality can reach as high as 90% in crops that are infected early in the growing season by vector aphids migrating from nearby infected grasses or volunteer cereals.
"Don't wait until the traditional early November spraying time if you're in an area that is affected – spray now with a suitable insecticide."
Any early flush of weeds should also be dealt with in the near future.
"Controlling weeds early in the season not only ensures you are minimising competition with the crop as it grows, but also gives you more options later on when pressure on spraying is greater and difficult weather conditions can make getting on the land difficult.
"Over reliance on Spring herbicide applications caused real congestion for many growers in the critical Spring fungicide & PGR spray window this year and the higher than average weed threat now could well be the result of inadequate control this last season."
