SPRUCE BUDWORM OUTBREAKS IN THE LOWER ST. LAWRENCE AND GASPE REGIONS

1961 ◽  
Vol 37 (3) ◽  
pp. 192-202 ◽  
Author(s):  
J. R. Blais
Keyword(s):  
Radial Growth ◽  
Spruce Budworm ◽  
White Spruce ◽  
Balsam Fir ◽  
Forest Composition ◽  
Growth Studies ◽  
Recent Outbreak ◽  
History Of

Evidence of past spruce budworm outbreaks in the lower St. Lawrence and Gaspé regions was obtained through radial-growth studies of balsam fir and white spruce. Outbreaks of this insect were known to have taken place in the Lower St. Lawrence in 1878 and 1912; this was confirmed by the present investigations. However, the data indicate that the 1912 infestation was of greater severity and duration than previously supposed. Forests in the Gaspé were thought to have escaped these past outbreaks. Although no trace was found of the 1878 infestation in the Gaspé, the present study clearly shows that the infestation of 1912 covered close to 9,000 square miles in this region.The recent outbreak of 1950 which affected both regions was generally more severe than that of 1912, especially in the Gaspé. Changes in forest composition appear to be responsible for this situation. Balsam fir, the preferred host of the spruce budworm comprised 46 per cent by volume of the Gaspé forests 30 years ago, but this has since increased to 80 per cent as a result of the destruction of large quantities of white spruce and birch through the respective action of the European spruce sawfly and the birch dieback. The history of past spruce budworm outbreaks indicates that conditions for the development and maintenance of such outbreaks are less favourable in the Gaspé than in the Lower St. Lawrence. This situation appears to be the result of the prevailing cool, moist climate of the Gaspé.

scholarly journals EFFECTS OF DEFOLIATION BY SPRUCE BUDWORM (CHORISTONEURA FUMIFERANA CLEM.) ON RADIAL GROWTH AT BREAST HEIGHT OF BALSAM FIR (ABIES BALSAMEA (L.) MILL.) AND WHITE SPRUCE (PICEA GLAUCA (MOENCH) VOSS.)

1958 ◽  
Vol 34 (1) ◽  
pp. 39-47 ◽  
Author(s):  
J. R. Blais
Keyword(s):  
Picea Glauca ◽  
Radial Growth ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
White Spruce ◽  
Balsam Fir ◽  
First Year ◽  
Growth Ratio ◽  
Breast Height

The relationship between spruce budworm defoliation and radial growth at breast height for balsam fir and white spruce trees of merchantable size was studied in various stands in northwestern Ontario. Defoliation was recorded yearly for these stands from the beginning of the infestation, and radial growth measurements were obtained from increment cores. The first year of radial growth suppression was calculated by comparing the growth of the affected species with that of jack pine and red pine trees by means of a growth-ratio technique. Apparent suppression in balsam fir and white spruce varied between stands, and, generally, occurred at the earliest in the second year and at the latest in the fourth year of severe defoliation. A wide ring at the base of the tree coinciding with the first year of suppression as reported by Craighead was non-existent.

LONG TERM STUDY OF THE EFFECTIVENESS OF AERIAL APPLICATION OF BACILLUS THURINGIENSIS – ACEPHATE COMBINATIONS AGAINST THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE)

1977 ◽  
Vol 109 (9) ◽  
pp. 1239-1248 ◽  
Author(s):  
O. N. Morris
Keyword(s):  
Bacillus Thuringiensis ◽  
Choristoneura Fumiferana ◽  
Larval Mortality ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
White Spruce ◽  
Balsam Fir ◽  
Population Densities ◽  
Long Term Study

AbstractBacillus thuringiensis (Dipel® 36B) mixed with a sublethal concentration of acephate (Orthene®) (O, S-dimethyl acetylphosphoramidothioate), an organophosphorous insecticide, was applied at 2.35–14 l./ha to white spruce (Picea glauca) and balsam fir (Abies balsamea) trees infested with spruce budworm, Choristoneura fumiferana (Clem.). The treatment rate was 20 Billion International Units of B. thuringiensis (B.t.) activity with or without 42 g of active ingredient of acephate/ha.The ground deposit of the standard Dipel wettable powder formulation was 12% of emitted volume compared with 21–32% for the Dipel 36B flowable. The viability of B.t. spores was drastically reduced after 1 day of weathering but a high level of biological activity by the spore–crystal complex persisted for up to 20 days post-spray due probably to crystal activity.The addition of about 10% of the recommended operational rate of acephate to the B.t. suspension increased larval mortality by 34% when applied at 4.7 l./ha. Reductions in budworm populations were 97–99% in B.t. + acephate plots and 86–90% in B.t. alone plots.Plots with moderate budworm densities of up to 27 larvae/100 buds on white spruce and 36/100 on balsam fir were satisfactorily protected from excessive defoliation in the year of spray by B.t. with or without acephate. Plots with higher population densities were not satisfactorily protected based on the branch sample examination but aerial color photographs indicated good protection to the top third of the trees. Population declines were greater and defoliation and oviposition were lower in the treated plots than in the untreated checks 1 year later without further treatment. Two years later the larval population densities in all plots were low but the density was twice as high in the untreated check as in the treated plots, indicating long term suppression by the treatments. Defoliation was negligible in all plots.The treatments had no deleterious effect on spruce budworm parasitism. The data indicate that the integrated approach using Bacillus thuringiensis – chemical pesticide combinations is a viable alternative to the use of chemical pesticides alone in spruce budworm control. Large scale testing is now warranted.

The Sensitivity of Young White Spruce to Spruce Budworm Defoliation

1991 ◽  
Vol 8 (4) ◽  
pp. 168-171 ◽  
Author(s):  
Harald Piene
Keyword(s):  
Volume Growth ◽  
Spruce Budworm ◽  
White Spruce ◽  
Balsam Fir ◽  
First Year ◽  
Average Volume ◽  
Shoot Production ◽  
Prolific Shoot

Abstract Relationships between defoliation and volume growth were determined for 68 young white spruce trees in a 20-year-old plantation defoliated over a 2-year period by the spruce budworm. In the first year of defoliation, intensities ranging from 7 to 89% of the current foliage did not influence volume growth significantly. Two consecutive years of defoliation, averaging over the 2-year period from 0-33, 34-66, and 67-100% of the current foliage, reduced average volume growth by about 6, 11, and 27%, respectively. White spruce is much less sensitive to defoliation than balsam fir. This is partly due to white spruce's ability to compensate for even moderate defoliation intensities by a prolific shoot production. North. J. Appl. For. 8(4):168-171.

scholarly journals ACCOUNT OF A RECENT SPRUCE BUDWORM OUTBREAK IN THE LAURENTIDE PARK REGION OF QUEBEC AND MEASURES FOR REDUCING DAMAGE IN FUTURE OUTBREAKS

1964 ◽  
Vol 40 (3) ◽  
pp. 313-323 ◽  
Author(s):  
J. R. Blais
Keyword(s):  
Radial Growth ◽  
Dead Wood ◽  
Spruce Budworm ◽  
Population Level ◽  
Growth Data ◽  
Temporary Reduction ◽  
Growth Studies ◽  
The Dead ◽  
Apparent Reasons

Pulpwood stands in the Laurentide Park region of Quebec were subjected to defoliation by the spruce budworm between 1946 and 1958. Progress of the outbreak was traced from survey records and from radial growth data from 102 localities. The apparent reasons for the temporary reduction in population level from 1951 to 1953, and for the collapse of the infestation in 1958 are discussed. Estimates based on information provided by the various operators in the area place the total amount of merchantable softwoods destroyed at 5.4 million cords, while calculations based on radial growth studies reveal that approximately 1.8 million cords were lost through reductions in increment. About 1.6 million cords were salvaged before the dead wood was rendered unusable by sapwood rots. Measures that would reduce losses from future outbreaks are proposed and discussed.

OPTIMAL SAMPLE SIZE FOR THE ESTIMATION OF SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE) POPULATIONS ON BALSAM FIR AND WHITE SPRUCE

1983 ◽  
Vol 115 (12) ◽  
pp. 1621-1626 ◽  
Author(s):  
Jacques Régnière ◽  
C. J. Sanders
Keyword(s):  
Population Density ◽  
Sample Size ◽  
Host Species ◽  
Spruce Budworm ◽  
White Spruce ◽  
Balsam Fir ◽  
Larval Population ◽  
Optimal Sample Size ◽  
Optimal Sample

AbstractAn equation is presented for the determination of sample sizes needed to estimate with a given precision the larval population density of spruce budworm on balsam fir and white spruce branch tips in Ontario. This equation is primarily applicable to low densities, but is valid to a density of 50 larvae/branch tip. The distribution of budworm larvae at densities below 0.1/branch tip is nearly random, and is aggregated at higher densities. Their distribution is the same on the two host species.

Trends in the frequency, extent, and severity of spruce budworm outbreaks in eastern Canada

1983 ◽  
Vol 13 (4) ◽  
pp. 539-547 ◽  
Author(s):  
J. R. Blais
Keyword(s):  
20Th Century ◽  
Large Scale ◽  
Spruce Budworm ◽  
Forest Composition ◽  
Eastern Canada ◽  
Clear Cutting ◽  
The Past ◽  
Spruce Stands ◽  
History Of

The history of spruce budworm (Choristoneurafumiferana (Clem.)) outbreaks for the past 200 to 300 years, for nine regions in eastern Canada, indicates that outbreaks have occurred more frequently in the 20th century than previously. Regionally, 21 outbreaks took place in the past 80 years compared with 9 in the preceding 100 years. Earlier infestations were restricted to specific regions, but in the 20th century they have coalesced and increased in size, the outbreaks of 1910, 1940, and 1970 having covered 10, 25, and 55 million ha respectively. Reasons for the increase in frequency, extent, and severity of outbreaks appear mostly attributable to changes caused by man, in the forest ecosystem. Clear-cutting of pulpwood stands, fire protection, and use of pesticides against budworm favor fir–spruce stands, rendering the forest more prone to budworm attack. The manner and degree to which each of these practices has altered forest composition is discussed. In the future, most of these practices are expected to continue and their effects could intensify, especially in regions of recent application. Other practices, including large-scale planting of white spruce, could further increase the susceptibility of forest stands. Forest management, aimed at reducing the occurrence of extensive fir–spruce stands, has been advocated as a long-term solution to the budworm problem. The implementation of this measure at a time when man's actions result in the proliferation of fir presents a most serious challenge to forest managers.

Variations in the foliar amino acid composition of flowering and non-flowering balsam fir (Abies balsamea (L.) Mill.) and white spruce (Picea glauca (Moench) Voss) in relation to outbreaks of the spruce budworm (Choristoneura fumiferana (Clem))

1971 ◽  
Vol 49 (7) ◽  
pp. 1005-1011 ◽  
Author(s):  
J. P. Kimmins
Keyword(s):  
Amino Acids ◽  
Picea Glauca ◽  
Host Plants ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
White Spruce ◽  
Balsam Fir ◽  
Apparent Correlation

The amino acids of new and old foliage of flowering and non-flowering balsam fir (Abies balsamea (L.) Mill.) and white spruce (Picea glauca (Moench) Voss) were investigated using two-dimensional descending paper chromatography. The data were analyzed for variation associated with age of foliage, age of tree, and flowering condition. The concentration of foliar amino acids was greater in balsam fir than in white spruce, and greater in new foliage than old foliage.The difference in concentration between foliage of flowering and non-flowering trees was smaller. However, the new foliage of flowering fir had higher levels of most of the amino acids examined than any other foliage category. This appears to reflect the known suitability of these foliage categories for spruce budworm larvae. While the data presented do not quantify the ecological significance of this apparent correlation, they do support the theory that variations in the nutritional quality of host plants play a very important role in the dynamics of herbivore populations.

Recurrence of Spruce Budworm Outbreaks for Two Hundred Years in Western Quebec

1981 ◽  
Vol 57 (6) ◽  
pp. 273-275 ◽  
Author(s):  
J. R. Blais
Keyword(s):  
Twentieth Century ◽  
Picea Glauca ◽  
Radial Growth ◽  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
White Spruce ◽  
Eastern Canada ◽  
Ottawa River ◽  
History Of ◽  
Growth Profiles

The history of spruce bubworm (Choristoneura fumiferana (Clem.)) outbreaks for the past two hundred years in the Ottawa River Valley in Quebec was retraced through radial-growth studies on old white spruce (Picea glauca (Moench)) and black spruce (Picea mariana (Mill.) B.S.P.) trees. The radial-growth profiles clearly indicate three suppression periods resulting from outbreaks that occurred in the twentieth century, each starting about 1910, 1940 and 1967. There is no evidence of an outbreak during the nineteenth century in this region. However, a reduction in radial-growth starting in 1783 observed on the only three specimens of white spruce over 200 years old, has the characteristics of that caused by a budworm outbreak. An interval of 127 years between this and the 1910 outbreak is similar to other long intervals between outbreaks recorded prior to the twentieth century for some other regions in eastern Canada.

Mortality of balsam fir and white spruce following a spruce budworm outbreak in the Ottawa River watershed in Quebec

1981 ◽  
Vol 11 (3) ◽  
pp. 620-629 ◽  
Author(s):  
J. R. Blais
Keyword(s):  
Twentieth Century ◽  
Spruce Budworm ◽  
White Spruce ◽  
Balsam Fir ◽  
Forest Roads ◽  
River Watershed ◽  
Ottawa River ◽  
High Incidence ◽  
Spruce Mortality ◽  
Mature Stands

Spruce–fir stands in the Ottawa River watershed in Quebec were subjected to defoliation by spruce budworm, Choristoneurafumiferana (Clem.), between 1967 and 1975. 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 these two species following the end of the infestation. The plots were established in 1975, the last year of defoliation, and revisted each year until 1979. Between 1975 and 1979, fir mortality increased from 44 to 91%, and spruce mortality from 17 to 52%. Thus, more than 50% of the trees of both species that died did so during the 4 years after cessation of defoliation. Mortality for both spruce and fir was as high for mixed (hardwoods and budworm hosts) as for coniferous (predominantly spruce and fir) stands. A survey along 710 km of forest roads conducted in the study area in 1980 indicated the degree of mortality observed in the plots was representative of that for the whole region, and that mortality in young stands (20–50 years) was almost as high as in mature fir stands. Since the beginning of the twentieth century, intervals between budworm outbreaks lasted about 30 years in the Ottawa River watershed. However, the high incidence of mortality of white spruce and of immature fir that occurred during the recent infestation was not observed during earlier infestations. Regeneration of fir is plentiful throughout the area, but it will take some time before these young trees attain maturity and become susceptible to budworm attack. The interval between this recent and the next budworm infestation should therefore be longer than preceding ones.

Insect–host relationships influencing disturbance by the spruce budworm in a boreal mixedwood forest

2004 ◽  
Vol 34 (9) ◽  
pp. 1870-1882 ◽  
Author(s):  
V G Nealis ◽  
J Régnière
Keyword(s):  
Life Cycle ◽  
Populus Tremuloides ◽  
Black Spruce ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
White Spruce ◽  
Host Tree ◽  
Balsam Fir ◽  
Insect Host ◽  
Boreal Mixedwood Forest

Demographic data from a 15-year outbreak of the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae), in a boreal mixedwood forest in Ontario, Canada, are used to interpret stand-level ecological disturbance in terms of susceptibility and vulnerability (mortality) of balsam fir (Abies balsamea (L.) Mill.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) BSP). All three host-tree species are highly susceptible for oviposition by the spruce budworm and all are suitable for completion of the budworm life cycle. Host-related differences in susceptibility arise from the degree of synchrony between spruce budworm phenology during the feeding stages and host-tree phenology. Spruce budworm density was highest on white spruce throughout the budworm's life cycle and over the course of the outbreak, but more rapid flushing and growth of current-year buds in white spruce reduced damage relative to that on balsam fir. Conversely, later flushing of current-year buds on black spruce led to a reduction in budworm density early in the season and a corresponding reduction in defoliation. The combination of high budworm densities and severe defoliation caused mortality first on balsam fir. By the end of the outbreak, 89% of the balsam fir component >10 cm DBH was eliminated compared with 49% of the white spruce in the same size class. The lower susceptibility of black spruce resulted in survival of all but the smallest size classes of that species. Nonhost species such as trembling aspen (Populus tremuloides Michx.) nearly doubled their basal area during the outbreak. The results link processes inherent in the insect–host relationship with the population ecology of the insect and the disturbance ecology of the forest.

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