More mild winters and wet summers will put cereal crops at higher risk from BYDV and other aphid-borne diseases. So said Rothamsted Research’s Richard Harrington, speaking at a joint Rothamsted/ HGCA ‘disease forecasting’ workshop in Kent last week.

He reckoned changing weather patterns could change how the virus interacted with host plants and, importantly, alter the life cycle of aphids, resulting in them being active all year round.

“Aphids usually don’t fly after the end of November, but it’s not going to be long before they’re flying through the winter. You don’t have to go very far into France for example, to find places where they’re already flying all year round.”

As a result, in some parts of the UK, after mild winters, it might be worthwhile spraying in the spring, up to growth stage 31, he said.

“Two mild winters with a wet summer in between – as this year – is very definitely bad news in terms of BYDV spread,” he added. “The higher the rainfall in June to August, the higher the number of bird cherry aphids in the autumn.”

What’s more, Dr Harrington said the probability of getting such circumstances was likely to increase due to climate change – particularly in northern and western areas. “In the south and east, the risk doesn’t really change – one in five years is likely to be bad for BYDV. But further north and west, more than half of future seasons could be bad BYDV years.”

He also thought warmer average temperatures would allow different strains of the virus to spread in the UK. The RMV strain, for example, was spread by the corn leaf aphid, which was becoming increasingly common as winters got milder and maize area increased.