Written in English
|Series||Technical notes / Lake States Forest Experiment Station -- no. 597, Technical notes (Lake States Forest Experiment Station (Saint Paul, Minn.)) -- no. 597.|
|Contributions||Lake States Forest Experiment Station (Saint Paul, Minn.)|
|The Physical Object|
|Pagination||2 unnumbered pages|
Key Words: Budworm, defoliation, tree mortality, red spruce, balsam fir. Spruce budworm (~hoiistoneura furniferaw Clem.) has been the most destructive forest insect in the spruce-fir (Picea- Abies) region of New England, with increasing frequency, extent, and severity of outbreaks during the last century (Mog et al. , Blais 1, a Cited by: Feeding by the caterpillars leads to tree damage and death. Damage includes Defoliation; Top kill (after several years of heavy feeding) Tree mortality (after about 5 years of heavy feeding) Weakened trees not killed by budworm are more vulnerable to other insects (bark . Spruce–fir stands in the Ottawa River watershed in Quebec were subjected to defoliation by spruce budworm, Choristoneurafumiferana (Clem.), between and Eighteen study plots were established in mixed and coniferous mature stands to determine impact of the infestation on balsam fir, Abiesbalsamea Mill., and white spruce, Piceaglauca (Moench) Voss, and the protracted mortality of Cited by: Spruce budworm (SBW; Choristoneura fumiferana (Clem.)) defoliation can cause severe growth reduction and mortality to spruce-fir (Picea-Abies) species in eastern North America.
top-killed, which often results in stem deformity, multiple leaders, or the death of the entire tree. In young western Figure 9.— Mature subalpine fir top-killed by the western spruce budworm. larch stands, sustained larval feed-ing and severance of new shoots causes top deformity and can reduce height growth by as much as 25 to 30 percent. top kill of leaders and some terminal branch shoots. Five to seven successive years of defoliation will lead to tree mortality. A single, complete defoliation commonly kills conifers. Monitoring: Beginning in May, look for frass and silk Defoliation damage caused by spruce budworm; note that the foliage is tied together with silk threads. (). We found that defoliation has the potential to both increase and decrease the probability of ignition depending on the time scale, ecoregion, and season examined. Most importantly, we found that lagged spruce budworm defoliation (8–10 yr) increases the risk of fire ignition whereas recent defoliation (1 yr) can decrease this risk. Mortality and top-killing of spruce-fir caused by repeated budworm defoliation. USDA For. Serv. Tech. Note , 2 pp. Stedinger, J.R., A spruce budworm-forest model and its implications for suppression programs.
Budworm feeding damage is first noticed on outer branch shoots in the upper crowns of spruce and fir trees. Partially eaten needles are webbed onto branch tips and turn a reddish-brown color. Long-term damage of budworm defoliation can result in top kill in 2 to 3 . Repeated budworm defoliation can cause top-kill and death in older and stressed trees. Balsam fir older than 60 and spruce over 70 years are prime targets. Repeated budworm defoliation causes tree mortality, reduction in growth rates, and reduced lumber quality. Eight hundred and fifteen () plots were established between and throughout. outbreak of spruce budworm were obtained by subjecting a national forest inventory to the spatially defined represent-ative patterns of defoliation. The use of these estimates in determining the status of Canada’s forests as a carbon source or sink is discussed. Key words:spruce budworm, defoliation, growth loss and mortality, carbon source.