Federal scientists are about to begin an aerial forest-spraying program outside Halifax, which they hope will slow the spread of the brown spruce longhorn beetle.

Twenty-seven hectares of forested land behind the Department of National Defence's Bedford Rifle Range will be sprayed starting in May with a synthetic chemical pheromone designed to disrupt the beetle's mating habits.

It's the same beetle responsible for destroying thousands of trees in Halifax's Point Pleasant Park, first confirmed in 1999. The destructive beetle has slowly spread to other areas in Nova Scotia.

Scientists have done smaller test sprays before in the area, on Crown land adjacent to the range last year.

The non-toxic pheromone was developed at Canadian Forest Service laboratory.

"We're testing that as a means to control the beetle, to suppress its population. so we can come up with a good tool that the provinces and whatever can use to slow the spread of the beetle in North America," said Jon Sweeny, the lead scientist on the program.

The program is a way to attack spot infestations, before the beetle gets a foothold and begins spreading, Sweeny said.

"We have significantly reduced the percentage of females mating by half," he said.

Environmental impacts

The area around the range is a popular walking area, but the scientists say the artificial pheromone poses no safety risk.

It will not be sprayed near people or streams and the pheromone is delivered in biodegradable flakes, Sweeny said.

Members of the Sackville River Association hope the spray can protect large stands of old growth trees in the local watershed.

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The brown spruce longhorn beetle has caused problems in Nova Scotia for more than a decade. ((Department of Natural Resources))

"We want these protected. We do see the attack of the spruce beetle and if this could be stopped, it'd be great, said Walter Regan, president of the association.

However, Regan said he wonders what the potential impact was on the waterways that his group has worked hard to protect.

"Aerial spray is a concern, we have to keep an eye on that because we use Atlantic salmon as an indicator of water quality, but I believe [spraying] should be begin."

Sweeny said there would be no water-quality monitoring because the program will follow provincial guidelines to not spray within 50 metres of a watercourse.

Sweeny described the material used in the biodegradable flakes as "similar to the material used for dissolving stitches, used in surgery on people and animals."

Hercon, the company responsible for the flakes, said moisture and microbes in the forested areas work on the polymer to break it down into water and C02.

Testing ends in October.