Around 400 metres of road is covered in glue on the A76, near Sanquhar, after a lorry overturned.
The road is expected to be closed for several hours.
The current diversion is 50 miles long.
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The Met Office have issued a yellow "Be Aware" warning of heavy rain for the region which is valid from 3pm Sunday until 3pm Monday
Emma Jesson brings you Saturday night's forecast
Christmas Eve which could be rather frosty, and at present, Christmas Day itself looks like being cold and clear with a few wintry showers