Highways England is facing backlash for spraying weed killer along the verges of the A47, destroying grass and plants.
Norfolk County councillor Sandra Squire, who took the case up with the government-owned company, said: "At Norfolk County Council we want to do a pollinator action plan and put in wildflower verges, while at the same time Highways England is spraying weed killer all along the A47. A little joined up thinking and environmental awareness wouldn't go amiss."
Professor Ben Garrod, from the UEA, also called on Highways England to explain the decision, asking: "Surely there's a better way to manage our verges at a time when biodiversity is in crisis?"
The weed killer was sprayed between King's Lynn and Norwich around road signs, lay-bys and slip roads.
A Highways England spokesman said this was to stop plants blocking signs and drainage.
"All the products we use are suitable for their purpose and we strive to take a balanced, responsible approach," they added.
But Mrs Squire urged Highways England to cut verges rather than spray the weed killer.
"I couldn't believe the vast swathes of brown and dead areas," she said.
The county's verges are havens for nature if they are not sprayed or fertilised, according to the Norfolk Wildlife Trust.
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