WITH TWO of the three precursors in place, signs are that the Barley Yellow Dwarf Virus risk to cereals this autumn will be high, a government entomologist has warned.

The mild 2003/2004 winter and recent wet summer only need to be followed by a mild autumn and winter for BYDV-carrying aphids to become a significant problem, said the CSL‘s Keith Walters.

“We reckon up to 2m ha are at risk of yield loss. It‘s a UK-wide problem.”

Along with Rothamsted Research, ADAS and SAC, CSL is developing a practical decision support system, which still needs validating, to help growers target treatments better.

The research behind it shows the risk of severe BYDV outbreaks is increased after two mild winters with an intervening wet summer, noted Syngenta‘s Bruce McKenzie.

“People should be on their toes this year if it‘s a mild autumn,” said Dr Walters.

Seed treatments, including Syngenta‘s thiamethoxam still awaiting approval, can help protect crops, according to the firm‘s Michael Tait.

But follow-up sprays, especially where low seed rates are used, are likely to be needed to stop aphids spreading the disease.

Hallmark Zeon (lambda-cyhalothrin) offers dose flexibility to provide good control options for high, moderate and low risk scenarios, he explained.