Using weather-based computer models, researchers in Britain predicted that climate change will expand the range and increase the severity of phoma stem canker, which already accounts for 900 million dollars (650 million euros) in losses each year.

The study, published in the Royal Society journal Interface, found that warmer winters have significantly advanced the date of stem canker appearance in spring, giving it more time to spread before harvest.

Eleven of the past 12 years rank among the dozen warmest years on record, while mean global atmospheric temperature have risen by 0.8 C (1.44 F) over the last century.

Plant pathologist Neal Evans, who led the research, forecast that the disease would move from England north to Scotland, where it does not currently exist.

The computer model "was developed as a tool to help guide fungicide applications timing by farmers," he said. "We realised we could extend its use ... to examine how global warming might impact on future epidemics."

The top rapeseed growers in the world are China, Canada, India, Germany, France and Britain, accounted for nearly 80 percent of worldwide harvests.

The United Nations authority on climate change has said earlier this year human activity is almost certain to blame for global warming, and warned that the Earth's average surface temperature could rise between 1.1 and 6.4 degrees by 2100.

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