PITYOPHTHORUS ORARIUS BRIGHT (COLEOPTERA: SCOLYTIDAE) IN A NORTHERN CALIFORNIA DOUGLAS-FIR SEED ORCHARD: EFFECT OF CLONE, TREE VIGOR, AND CONE CROP ON RATE OF ATTACK

1994 ◽  
Vol 126 (5) ◽  
pp. 1111-1118 ◽  
Author(s):  
Nancy G. Rappaport ◽  
David L. Wood

AbstractThe geographic range of the Douglas-fir twig beetle, Pityophthorus orarius Bright, was extended beyond the original provenance of southern British Columbia to northern California. A survey of 457 Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] trees in 1985 revealed that those with heavy cone crops were more likely to be infested by twig beetles than were those with a light crop. Furthermore, attack rates differed among clones. A second survey done in 1987 confirmed the importance of clone and cone crop in attack rate. In this survey, stressed trees were attacked at a higher rate than unstressed trees. Beetle distributions appeared clumped in both surveys, possibly because of semio-chemicals or oviposition behavior.

1998 ◽  
Vol 28 (8) ◽  
pp. 1198-1206 ◽  
Author(s):  
Paige E Axelrood ◽  
William K Chapman ◽  
Keith A Seifert ◽  
David B Trotter ◽  
Gwen Shrimpton

Poor performance of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantations established in 1987 has occurred in southwestern British Columbia. Affected sites were planted with 1-year-old container stock that exhibited some root dieback in the nursery. A study was initiated in 1991 to assess Cylindrocarpon and Fusarium root infection in planted and naturally regenerating (natural) Douglas-fir seedlings from seven affected plantations. Percentages of seedlings harboring Cylindrocarpon spp.and percent root colonization were significantly greater for planted seedlings compared with natural seedlings. A significant linear trend in Cylindrocarpon root colonization was observed for planted seedlings with colonization levels being highest for roots closest to the remnants of the root plug and decreasing at distances greater than 10cm from that region. This trend in Cylindrocarpon colonization was not observed for natural seedlings. Cylindrocarpon destructans (Zins.) Scholten var. destructans and C.cylindroides Wollenw. var. cylindroides were the only species isolated from planted and natural conifer seedlings. For most sites, percentage of seedlings harboring Fusarium spp.and percent Fusarium root colonization were less than for Cylindrocarpon. Recovery of Fusarium spp.from seedlings and root colonization levels were not significantly different for planted and natural seedlings from all sites.


Author(s):  

Abstract A new distribution map is provided for Contarinia pseudotsugae Condrashoff (Diptera: Cecidomyiidae). Hosts: Douglas fir (Pseudotsuga menziesii). Information is given on the geographical distribution in Europe (Belgium, France, Germany and Netherlands) and North America (Canada, British Columbia, USA, California, Idaho, Michigan, Montana, Oregon, Pennsylvania and Washington).


Author(s):  

Abstract A new distribution map is provided for Rhabdocline pseudotsugae Syd. Hosts: Douglas fir (Pseudotsuga menziesii). Information is given on the geographical distribution in EUROPE, Belgium, Britain, Czechoslovakia, Denmark, France, Germany, Irish Republic, Netherlands, Norway, Poland, Romania, Sweden, Switzerland, Yugoslavia, NORTH AMERICA, Canada (Alberta, British Columbia), USA.


Author(s):  

Abstract A new distribution map is provided for Dendroctonus pseudotsugae Hopkins Coleoptera: Scolytidae Hosts: Mainly Douglas fir (Pseudotsuga menziesii), also other Pseudotsuga spp. Information is given on the geographical distribution in NORTH AMERICA, Canada, Alberta, British Columbia, Mexico, USA, Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Texas, Utah, Washington, Wyoming.


2018 ◽  
Vol 48 (7) ◽  
pp. 809-820 ◽  
Author(s):  
Neil P. Thompson ◽  
Kathy J. Lewis ◽  
Lisa M. Poirier

Drought tolerance of trees may be affected by competition, but most studies quantifying the relationship do not consider the effect of stem clustering. Trees are often clustered in interior Douglas-fir (Pseudotsuga menziesii var. glauca (Mayr) Franco) forests near the grassland interface in central British Columbia due to past harvesting practices or habitat management for mule deer (Odocoileus hemionus hemionus (Rafinesque, 1817)). Climate change projections indicate continued increases in temperature, an outcome that would stress trees growing in dry environments. Trees placed in different states of competition by mechanical harvesting in the 1970s were sampled to provide a 40-year comparison of three levels of competition during 1–2 year droughts. Tree-ring analysis was used to assess the reduction in growth during drought years and resumption of growth in subsequent years. A clear separation of growth rates was evident between open-growing trees, trees on the edge of harvesting trails, and trees within the unharvested interior. Edge trees had intermediate growth rates but no differences were found in the long-term climate–growth relationship compared with open-growing trees. Both Edge and Open classes showed less relative growth reduction during droughts than Interior trees growing between harvest trails. Precipitation throughfall rates and competition for resources are likely driving short-term drought tolerance in combination with other factors.


2010 ◽  
Vol 40 (1) ◽  
pp. 155-166 ◽  
Author(s):  
M. G. Cruickshank ◽  
B. Jaquish ◽  
A. F.L. Nemec

The objectives of this study were to (i) develop a methodology for screening conifer seedlings for resistance to Armillaria ostoyae (Romagn.) Herink and (ii) screen a population of interior Douglas-fir ( Pseudotsuga menziesii var. glauca (Biessn.) Franco) population for resistance to A. ostoyae. Eighteen potted seedlings from each of 86 half-sib interior Douglas-fir families were challenged with inoculum in a 3-year greenhouse trial. The seed originated from four geographically distinct tree breeding zones that represent physically and biologically different environments in southeastern British Columbia. Mortality and the final percent survival of inoculated trees showed differences among the families (survival range 0%–61.1%) and breeding zones (survival range 6.6%–25.3%). Maximum heritability index (0.19) occurred at 28 months. Survival analyses revealed that most of the differences in survival could be explained by the zone from which the family originated. The less susceptible seedlings originated from the drier and warmer zones and limited the spread of the fungus in the root system. Moderate levels of family variation in resistance to A. ostoyae and low-moderate heritability suggest that, in interior Douglas-fir, gains in resistance can be achieved through breeding.


1975 ◽  
Vol 53 (20) ◽  
pp. 2297-2302 ◽  
Author(s):  
A. Funk

Three new species of ascomycetes and two coelomycetes are described from diseased Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) from coastal British Columbia, Canada, viz., Coccomyces pseudotsugae n. sp., Phragmoporthe pseudotsugae n. sp., and Botryosphaeria pseudotsugae n. sp.; Phomopsis portei n. sp. and Haplosporella sp. are associated with the latter two ascomycetes, respectively, and possibly represent their conidial states.


1991 ◽  
Vol 123 (6) ◽  
pp. 1219-1228 ◽  
Author(s):  
Nancy Rappaport ◽  
Alain Roques

AbstractThe within-cone distribution of Megastigmus spermotrophus Wachtl (Hymenoptera: Torymidae), the Douglas-fir seed chalcid, infesting Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] cones from north-central France was compared with that in samples from California. Results indicate that the mid-region of cones was more intensively utilized by seed chalcids in France than in California, whereas in the northwestern United States the mid-region is characteristically occupied by dipteran and lepidopteran species. This difference in distribution may explain the large discrepancy in infestation rates on the two continents. The potential impact of this finding on pest management strategies is discussed.Cones were measured and dissected or X-rayed to determine seed chalcid infestation levels. Analysis of covariance performed on data from cones that were collected in 1986 and dissected showed cone diameter at maturity to be a highly significant factor in attack rate, although slopes were different among clones. Between-tree variation was also significant, but clonal source was not. Cone diameter, clonal source, and between-tree variation constituted 87.1% of the variation in rate of attack by the seed chalcid. Although clone was not a significant factor in data from dissected cones, X-rayed cones showed significant differences in attack rates for some clones.


Author(s):  
Birte Pakull ◽  
Pascal Eusemann ◽  
Janine Wojacki ◽  
Diana Ahnert ◽  
Heike Liesebach

AbstractIn Germany, Douglas fir (Pseudotsuga menziesii Franco) is seen as a valuable species for future cultivation in times of climate change. Local seed production in seed stands and seed orchards may secure that local adaptation is transferred to the next generation, but small population sizes could lower genetic diversity and thus future adaptability. Here we analyse the transfer of genetic diversity from parent to offspring generation in four older German seed orchards. We detected low pollen contamination rates due to high levels of spatial isolation. Even with a relatively low number of 40 clones, seed orchard design with randomized and repeated planting of clones led to low selfing rates, and despite uneven parental contributions, the number of successful parents and the level of genetic intermixture were high enough to allow the transfer of an adequate part of the genetic diversity to the next generation. Larger numbers, however, might be needed to reliably conserve the entire genetic diversity over succeeding generations. Conclusions on the establishment of future seed orchards and regarding areas requiring further research are drawn at the end of the paper.


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