Environment

Urban Forestry

History of the Douglas fir Tussock Moth in the Kamloops Area

In 2006 several blue spruce trees (in Juniper, at the airport and in upper Sahali) on private property were severely defoliated (Figure 9). This is considered a possible precursor to an outbreak. Although defoliated sites were too small to detect during the aerial overview surveys, several small pockets of severe defoliation were observed in the summer of 2007 from ground surveys around Robbins Range and Barnhartvale.

Figure 9 - Douglas-fir tussock moth feeding on a blue spruce at the Kamloops Airport

In the fall of 2007 the MOFR conducted egg mass surveys for DFTM in various crown land forests near Kamloops. Egg mass numbers confirm that an outbreak is expected for the spring of 2008. Areas just past Barnhartvale and near Cherry Creek (some of the closest sites to the City of Kamloops) received a spring aerial treatment program with a species-specific nucleopolyhedrosis virus (NPV).

This virus is always present at low levels in the tussock moth population, and is the cause of an outbreak decline in nature. Unfortunately, this usually occurs after significant tree damage is done, unless higher levels of NPV are introduced early in the outbreak cycle. NPV is restricted from use over populated areas and therefore cannot be used to treat residential or urban recreational areas. Areas of Barnhartvale and Hefley Creek were significantly impacted by Tussock Moth during the late spring and early summer of 2008.

Impacts of Douglas-fir Tussock Moth
The Douglas-fir tussock moth has the potential to cause significant mortality due to defoliation. In addition, top-kill, growth reduction, and secondary attacks by insects and fungi may follow severe defoliation.

Control Strategies
The best way to detect rising DFTM populations is through the use of pheromone traps, which should be placed in all the city forested areas of concern. The cardboard traps and associated pheromone lures are economical and easy to install.

Traps should be installed in the late spring and assessed in the early fall. If trap catches indicate a significant population, egg mass surveys to determine the infestation boundaries should be conducted that fall.

For More Information: www.for.gov.bc.ca/hfp/publications/00198/dftm.htm

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Contact
Urban Forest
955 Concordia Way
Kamloops, BC V2C 6V3
ph (250)828-3461
fax (250) 828-3790
email scook@kamloops.ca

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