Kirwee residents Frank, 75, and Margaret, 74, Brenmuhl were involved in a head-on collision on State Highway 73 at Kirwee about 9.30pm on Thursday last week.
Margaret died at the scene and Frank was taken to Christchurch Hospital in a critical condition, but died the next day.
The Brenmuhls moved to Hinau in the upper Grey Valley in 1984, where they had a dairy farm.
Mrs Brenmuhl was a teacher at Sacred Heart School in Reefton, while Mr Brenmuhl held leadership positions with Federated Farmers West Coast.
In 2005, he was elected as chairman of Dairy Farmers of New Zealand, and six years later put his name in the hat for national Federated Farmers president.
The couple left the Coast in about 2007, relocating to a walnut orchard they had developed near West Melton.
Mr Brenmuhl also served a term as president of North Canterbury Federated Farmers.
Police offered their condolences to the family.
"Our deepest thoughts and sympathies are with their family at this extremely difficult time."
The driver of the other vehicle involved in the collision remains in Christchurch Hospital in a stable condition.
"Our investigation into the crash remains ongoing. No charges have been laid at this stage."
Their funeral will be held on Monday at St Joseph's Catholic Church in Darfield.
-Additional reporting Laura Mills
