[Vision2020] fyi- Forest Health

[Lynn McCollough]

A while ago I asked if anyone knew what was happening to the trees
near Plummer. I have since learned it is a Tussock Moth infestation.

Through aerial surveys in 2010, Douglas Fir Tussock Moth (DFTM)
infestation and defoliation was mapped, with approximately 570 acres
affected in eastern Spokane County and close to 8,500 acres with
defoliation in northern Idaho.
The damage primarily affects grand fir and Douglas-fir. Defoliation
damage has been moderate, affecting the top third of the tree crowns.
This damage can reduce growth, cause top-kill of mature trees and may
predispose some trees to attack by bark beetles. Understory fir trees
and saplings may be killed DFTM infestations. Recreation can also be
affected in areas with tussock moth present because the caterpillars’
hairs are a skin irritant to many people.
The outbreak in the Plummer/Worley area is now significant, with heavy
defoliation occurring.
Outbreaks typically collapse within two to four years due to a buildup
of natural enemies, such as a virus and parasites. Most likely, 2010
was the second year of this outbreak.