Red Trees at Mid-Elevation

This week saw coniferous trees turning red across the mid-elevations of Whistler Valley. An outbreak of western spruce budworm is showing in areas above White Gold, Function Junction and along Sproatt and Rainbow Mountains. The outbreak is happening across the coast/interior transition forests from Whistler to Hope and seems to be restricted to the band of higher elevation forests (~800-1100m).

The western spruce budworm is a native defoliator of interior Douglas-fir in British Columbia. It is not an introduced species. Outbreaks have been recorded in BC since the early 1900’s to the present day. In 1987 and again in 2007-2008, over 800,000 hectares were infested by the budworm, mostly in the southern interior of the province. Budworm outbreaks may be sustained for years.

The western spruce budworm feeds primarily on Douglas-fir. True firs, larch and spruce may also be affected. The caterpillars feed on the new needles, but will move onto the older needles if all new foliage is consumed. Trees appear reddish in colour once needles have been fed upon. Attack does slow down growth and can affect tree form.

Here is a quick spruce budworm fact sheet.

At this point, the Cheakamus Community Forest is monitoring the situation in connection with the Ministry of Forests and taking a wait and see approach. If tree mortality begins to occur at an unacceptable rate over the next couple of years, the CCF will work with the MOF to determine next steps. Currently, the only viable management option is to aerial spray with Bacillus thuringiensis var. kurstaki, a biological agent that kills the caterpillar when it eats the treated tree needles and is harmless to other species.

The CCF is working over the long term to make our forests less susceptible to a number of risks such as climate change, wildfire, drought and insect outbreaks. We do that by converting stands to alternate species, planting a mix of species, altering stand structure and density through harvesting practices and stand improvements.

Thanks to everyone who contacted us about what they were seeing in the forests.

Check out the Pique Newsmagazine’s online story.