Western Spruce Budworm Damage Affects Form and Height Growth of Western Larch

1973 ◽  
Vol 3 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Wyman C. Schmidt ◽  
David G. Fellin
Keyword(s):  
Feeding Behavior ◽  
Apical Dominance ◽  
Spruce Budworm ◽  
Height Growth ◽  
Western Spruce Budworm ◽  
Western Larch ◽  
Reduced Height ◽  
Lateral Shoots ◽  
Terminal Shoot ◽  
Usual Diet

An unusual feeding behavior of the western spruce budworm (Choristoneuraoccidentalis Freeman) reduced height growth and deformed young western larch (Larixoccidentalis Nutt.). On western larch, budworm larvae did not confine their feeding to foliage, their usual diet on other conifers; they also fed on and severed stems of current-year terminal and lateral shoots. A 5-year study in young larch stands showed that: (1) amount and severity of budworm damage increased annually, (2) all trees were damaged sometime during the study, (3) severance of the terminal shoot was the most serious type of budworm damage to larch, (4) severances reduced net height growth at least one-fourth and resulted in forked, bushy-topped trees, and (5) specific forks in the tree did not persist more than 5 years because of the strong apical dominance characteristic of larch.

Ants and birds reduce western spruce budworm feeding injury to small Douglas-fir and western larch in Montana

1984 ◽  
Vol 9 (3) ◽  
pp. 185-192 ◽  
Author(s):  
Clinton E. Carlson ◽  
Robert W. Campbell ◽  
Leon J. Theroux ◽  
Thomas H. Egan
Keyword(s):  
Spruce Budworm ◽  
Douglas Fir ◽  
Western Spruce Budworm ◽  
Western Larch

Relations among stand structure, dispersal of second-instar western spruce budworm, defoliation, and height growth of young conifers

1988 ◽  
Vol 18 (6) ◽  
pp. 796-802
Author(s):  
Clinton E. Carlson ◽  
Ward W. McCaughey ◽  
Leon J. Theroux
Keyword(s):  
Ponderosa Pine ◽  
Stand Structure ◽  
Basal Area ◽  
Spruce Budworm ◽  
Height Growth ◽  
Western Montana ◽  
Western Spruce Budworm ◽  
Mature Trees ◽  
Subalpine Fir ◽  
Host Trees

Local stand structure had little influence on dispersal of second-instar western spruce budworm (Choristoneuraoccidentalis Freeman). Numbers of dispersing larvae caught on traps averaged 37 larvae/m2 in the cut stands, as high as were found in adjacent uncut stands, and were not related to basal area of overstory in harvested stands, distance to the adjacent uncut stands, or budworm populations in the uncut stands. Despite high numbers of dispersing larvae, defoliation of host regeneration in cut stands was low (87% of the nonlarch host incurred less than 25% defoliation) and was not predictable (p ≤ 0.05) from dispersing larvae. Defoliation of mature trees in the adjacent uncut stands averaged 20% and ranged to 45%. Three-year height growth of postharvest host conifers in the cut stands increased with smaller overstory basal area, greater initial height, and greater crown ratio, but was not affected by the small amount of budworm defoliation. Regression models of 3-year height growth were similar among host western larch (Larixoccidentalis Nutt.), grouped nonlarch hosts (Douglas-fir, Pseudotsugamenziesii var. glauca (Beissn.) Franco; grand fir, Abiesgrandis (Dougl.) Forbes; and subalpine fir, A. lasiocarpa (Hook.) Nutt.), and grouped nonhosts (ponderosa pine, Pinusponderosa Dougl.; and lodgepole pine, P. contorta var. latifolia). Larval dispersal may be influenced more by forestwide conditions and spring weather than by local stand factors. Larvae reaching target seedlings likely are removed by predators such as birds and ants. Vigorous small host trees appear to be poor habitat for budworms; the insect had little effect on height growth of 5- to 20-year-old seral conifer stands of western Montana.

Douglas-fir height growth affected by western spruce budworm

1983 ◽  
Vol 13 (3) ◽  
pp. 445-450 ◽  
Author(s):  
G. A. Van Sickle ◽  
R.I. Alfaro ◽  
A.J. Thomson
Keyword(s):  
British Columbia ◽  
Recovery Period ◽  
Spruce Budworm ◽  
Site Index ◽  
Height Growth ◽  
Douglas Fir ◽  
Western Spruce Budworm ◽  
Total Height

Detailed dissections of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) trees repeatedly defoliated by the western spruce budworm (Choristoneuraoccidentalis (Freeman)) in two areas of British Columbia indicated that budworm severely affected height growth. Dissected trees lost an average 7.3 internodes in each infestation, of which 4.2 were destroyed or failed to grow during the budworm feeding and recovery periods, and 3.1 were existing internodes lost to dieback. An average of one internode of subnormal size, produced during the recovery period, was also present. Total height was reduced by 32% (11.4 m) and 19% (5.9 m) in areas that sustained four and two infestations respectively. Budworm infestations lead to an underestimation of the site index for Douglas-fir in the affected areas.

A method for sampling western spruce budworm pupae.

1981 ◽  
Author(s):  
Nilima Srivastava ◽  
Roy C. Beckwith ◽  
Robert W. Campbell ◽  
Torolf R. Torgersen
Keyword(s):  
Spruce Budworm ◽  
Western Spruce Budworm

Chemistry and field evaluation of the sex pheromone of western spruce budworm,Choristoneura occidentalis, Freeman

1982 ◽  
Vol 8 (2) ◽  
pp. 339-350 ◽  
Author(s):  
H. T. Cory ◽  
G. E. Daterman ◽  
G. D. Daves ◽  
L. L. Sower ◽  
R. F. Shepherd ◽  
...  
Keyword(s):  
Sex Pheromone ◽  
Spruce Budworm ◽  
Field Evaluation ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm

Baculoviruses in populations of western spruce budworm

2015 ◽  
Vol 127 ◽  
pp. 76-80 ◽  
Author(s):  
V.G. Nealis ◽  
R. Turnquist ◽  
B. Morin ◽  
R.I. Graham ◽  
C.J. Lucarotti
Keyword(s):  
Spruce Budworm ◽  
Western Spruce Budworm

The effects of summer shoot production on height growth components of seedlings of California red and white fir

1992 ◽  
Vol 22 (5) ◽  
pp. 690-698 ◽  
Author(s):  
Stephen W. Hallgren ◽  
John A. Helms
Keyword(s):  
Soil Moisture ◽  
Growing Season ◽  
Shoot Elongation ◽  
Height Growth ◽  
Shoot Morphology ◽  
Apical Dome ◽  
White Fir ◽  
Shoot Production ◽  
Terminal Shoot ◽  
Needle Primordia

Morphogenesis of the terminal shoot was studied in 2-year-old seedlings of California red fir (Abiesmagnifica A. Murr.) and two elevational sources of white fir (Abiesconcolor (Gord. & Glend.) Lindl.). Seedlings were either watered or left unwatered during the growing season in order to produce different shoot morphologies and seedlings with and without a summer shoot. Under favorable soil moisture, the frequency of summer shoot production was 32, 53, and 82% for red fir and high- and low-elevation white fir, respectively. Drought from mid-May to mid-September reduced summer shoot production to less than 1% in both species. Spring shoot morphology was not an indicator of capacity to produce a summer shoot. Rate of primordium production was directly related to apical dome diameter. However, when the normal spring increase in apical dome diameter was arrested by summer shoot elongation, the rate of primordium production appeared to be unaffected. Although the apical and subapical meristems were active at the same time, they did not appear to be antagonistic. The major effects of producing a summer shoot were as follows: (i) elongation of 60–120% more intemodes in the current growing season, (ii) production of 15–40% more needle primordia in the overwintering bud, (iii) production of 30–60% more primordia annually, and (iv) increase in the percentage of total primordium production that developed into needles from 60% to 75–80%.

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