Now that the pace of B.C.’s pine beetle epidemic has slowed, the Forest Ministry is going after public enemy No. 2: budworm.
To combat the pest, the ministry plans to spray an organic insecticide on 28,000 hectares of forest, primarily Douglas fir, spread over 21 blocks throughout the South Okanagan.
“We’ve lost such vast areas of our pine, that from a forestry perspective, we just can’t afford to lose yet another species. So that’s why we’re trying to be pretty proactive about budworm,” said entomologist Lorraine Maclauchlan, who is spearheading the ministry’s spray program in the region.
B.C. is in the midst of its worst-ever budworm outbreak.
The bugs defoliated 614,000 hectares last year, Maclauchlan said, about half of which was in the Thompson-Okanagan, and have now been spotted as far north as Quesnel.
“We’ve had years that are kind of equivalent in hectarage, it’s just that this has gone on and on and on,” she said.
She said climate change has likely helped its spread, while the thinning of pine trees has made fir stands more amenable to the insect.
Budworms feed on a tree’s foliage, which impairs the host’s ability to carry out photosynthesis. While that stunts a mature tree’s growth, it doesn’t usually kill it, Maclauchlan explained.
“Simply from a timber standpoint, you’re not putting on any volume on stands where you have budworm.”
However, budworms also drop down through multi-layered stands onto younger trees, which can die from the resultant defoliation.
“What we’re really trying to protect is our next age class or group of trees, that understory component,” Maclauchlan added.
An industry representative agreed the budworm is “definitely” a concern.
“Especially because it does have the ability to really impact our mid-term timber supply,” said Archie MacDonald, general manger of forestry for the Council of Forest Industries. “These would be the younger trees that would grow up and hopefully take the place of the older, dead pine.”
MacDonald said the Okanagan’s forests contain a “reasonable percentage” of Douglas fir, which is a “very important species.” It’s highly sought-after as a building product, he continued, because of its appearance and strength.
The spray treatment is expected to be applied this week, weather permitting, by helicopter. The insecticide, Foray 48B, is a bacterium harmful only to budworms and does not pose a risk to humans or other wildlife. Maclauchlan said the application costs $35 to $40 per hectare.
As large as the budworm outbreak may seem, it still pales in comparison to the pine beetle epidemic. According to the latest government data, the beetle affected 18-million hectares of forest in B.C. between 1999 and 2011, and killed an estimated 710-million cubic metres of timber. To put that in perspective, the current annual allowable cut for all of B.C. is 78.1 million cubic metres.