Scientists in New Brunswick are clashing over whether the use of herbicides on Crown land has affected the province's deer herd.

Last week a deer biologist, who is now retired from the Natural Resources department, joined with nature groups to call for the use of herbicide to be made an election issue.

Rod Cumberland

Former Natural Resources deer biologist Rod Cumberland believes people in the department are fearful of speaking out about the forest policy because they fear for their job. (CBC)

"As a deer biologist, it's disconcerting for me to hear things over and over again about how minimal herbicide is used and what minimal effect it has on the forest," said Rod Cumberland.

Cumberland estimates half a billion tonnes of food has been taken away from deer Crown forest over the last 20 years by herbicides killing small hardwood growth.

However, that view is being countered by R.A. Lautenschlager, executive director of the Atlantic Canada Conservation Data Centre in Sackville, who was one of the researchers who studied the topic in the 1980s.

"In the eighties, we had no idea what those [herbicides] would do to deer foods, moose foods," said Lautenschlager. "Deer foods were quickly determined not to suffer from herbicide treatment. They weren't reduced much at all and would commonly increase."

Lautenschlager said he worked with tamed moose and deer populations to study their feeding habits.

"Certainly hardwood browse is important in the winter, but the real thing that puts deer in condition to go through the winter are the kinds of food they get during the summer, and that's low-growing herbaceous stuff.

"It's not that they don't eat some hardwoods, they absolutely do," said Lautenschlager. "But the quality foods they get are the low-growing herbaceous stuff and it's stuff like that that increases following those treatments."

Lautenschlager says peer-reviewed literature shows "there is a complete consensus this is not a problem for deer.

"That consensus is now quite old," he said. "Since then, people have stopped thinking about that because it was so clear it wasn't a problem.

"You don't want to do research into something that is clearly not a problem. Nobody is going to publish it."

On Tuesday, Lautenschlager​ and Cumberland went head-to-head in a debate on the topic on Information Morning in Fredericton.