New Brunswick

Insects that pose the biggest threat to Christmas trees

It's the centrepiece of your Christmas decorations, where everyone heads on Christmas Day, but keeping it spruced up takes insect knowledge.

Scientist Rob Johns spends his days researching how to keep pests off of Christmas tree

Rob Johns of the Atlantic Forestry Centre in Fredericton helps tree growers deal with Christmas tree pests. (Radio-Canada)

It's the centrepiece of your Christmas decorations, where everyone heads on Christmas Day, but keeping it spruced up takes insect knowledge.

Scientist Rob Johns is the tree growers' go-to man to make sure trees overcome disease and inclement weather.

And in his words, those trees can have a "low tolerance" for insects — particularly spruce budworm and the gall midge.

"Things that we wouldn't worry about in a normal forest we would worry about for Christmas trees," Johns told Information Morning Fredericton.

Esthetic damage to the tree can occur when "an insect chews on the needles in the branches."

The worst culprits

Johns said the worst pests for Christmas trees are often the ones that we don't notice. In Nova Scotia, for example, the balsam gall midge is too small to notice until it's too late.

"It's just a tiny little insect that lays this baby inside a single needle," he said. "They can lay millions of them all over the place all like all over these new needles.

"After they're done feeding the needles fall off. And so what that leaves on your Christmas tree is these little twigs at the tips of your branches, which of course nobody wants.

"We don't worry about those in large trees because we're not worried about that kind of esthetic damage. But for a Christmas tree, there's a huge problem."

Spruce budworm is especially bad in areas crowded with older trees, Johns said.

"It doesn't tend to hit young trees unless your Christmas tree stand is surrounded by trees that are infested with spruce budworm," he said.

For reasons scientists don't yet fully understand, spruce budworm outbreaks occur in 35-year cycles. The insect feeds off thorns of fir and spruce trees, leading to defoliation. (Radio-Canada)

And moths are another threat, specifically the white-marked tussock moth in Nova Scotia, he said.

"It's a big caterpillar. It also feeds on that new growth, so that can be a really big problem."

How to stop insect attacks

Johns said his research at Natural Resources Canada's Atlantic Forestry Centre is mainly to help monitor and identify insects and to try to figure out what growers can do when they have insect pests in their stands.

When there is an insect threat, Johns said, the tree growers' most important tool is the pruner.

"One of the things that Christmas tree growers do just in the course of shaping their trees, is prune the tips of the branches off," he said.

"In a lot of cases, the pests that cause the most damage [to] Christmas trees happen to feed on that new growth that they're clipping off."

Johns said when worse comes to worst, some growers use insecticide, but there's "a lot of pressure to have organic trees," nowadays, especially if growers want to export to the United States.

A Christmas tree farm in New Brunswick. (Shane Fowler/CBC)

O Christmas ladder?

For someone so focused on Christmas trees, it may seem strange that Johns hasn't had a Christmas tree in his own home in years.

He prefers a Christmas ladder, and idea that came from a colleague.

"He has a ladder, like an old antique ladder, and they wrap it in garlands and Christmas lights," said John. "And they basically just hang all their decorations on that. And they put the gifts on the steps.

"There's nothing better than folding up my ladder at the end of the season and hanging it up down in my basement, only to go get it for next year."

With files from Information Morning Fredericton

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