Promotion of seed production in Douglas-fir grafts by girdling + gibberellin A4/7 stem injection, and effect of retreatment

New Forests ◽  
1991 ◽  
Vol 5 (1) ◽  
pp. 23-34 ◽  
Author(s):  
Stephen D. Ross ◽  
Ralph C. Bower
Keyword(s):  
Seed Production ◽  
Douglas Fir ◽  
Stem Injection

CONSUMPTION OF VARIOUS DOUGLAS-FIR CONE STRUCTURES BY BARBARA COLFAXIANA (LEPIDOPTERA: OLETHREUTIDAE)

1977 ◽  
Vol 109 (9) ◽  
pp. 1293-1294
Author(s):  
T. Evan Nebeker
Keyword(s):  
Energy Transfer ◽  
Seed Production ◽  
Energy Budget ◽  
Forest Ecosystem ◽  
Larval Stage ◽  
Douglas Fir ◽  
National Forest ◽  
Larval Instars ◽  
Production Area

During 1971 a study was conducted to determine the amount of the various Douglasfir cone structures (bracts, scales, and seeds) consumed by the Douglas-fir cone moth, Barbara colfaxiana (Kft.), in the Buckhead Seed Production Area, Willamette National Forest, Oregon. It was not the intent of this study to develop a complete energy budget for B. colfaxiana, but rather to determine the number of calories consumed, on the average, by an individual during the larval stage. The behavior of the various larval instars has been discussed by Radcliffe (1952), Keen (1958), Hedlin (1960), and Nebeker (1977). The calorie was selected as the unit of measure due to its usefulness in modeling energy transfer from one component to another in the forest ecosystem.

Further observations on the pollination mechanism and seed production of Douglas-fir

1982 ◽  
Vol 12 (2) ◽  
pp. 431-434 ◽  
Author(s):  
John N. Owens ◽  
Sheila J. Simpson
Keyword(s):  
Seed Production ◽  
Pollen Grains ◽  
Germination Percentage ◽  
Douglas Fir ◽  
Pollination Mechanism ◽  
Supplemental Pollination

The pollination mechanism of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) was studied. Pollen stained five different colors and applied to the same conelets at five different times showed that the pollen applied on the 1st and 3rd days after conelets became receptive was taken into the micropyle in significantly greater quantities than pollen applied at later dates. A second supplemental pollination did not increase the seed efficiency for individual cones. Seeds produced when an average of less than 1.2 pollen grains were taken into the micropyle had essentially the same germination percentage and proportion of abnormal germinants as seeds resulting when an average of 3.4 or more pollen grains were taken into the micropyle.

scholarly journals Unexpected parasitism of Douglas-fir seed chalcid limits biocontrol options for invasive Douglas-fir in New Zealand

2021 ◽  
Vol 74 (1) ◽  
pp. 70-77
Author(s):  
Sonia Lee ◽  
Simon V. Fowler ◽  
Claudia Lange ◽  
Lindsay A. Smith ◽  
Alison M. Evans
Keyword(s):  
Biological Control ◽  
New Zealand ◽  
Seed Production ◽  
Biocontrol Agent ◽  
Biological Control Agent ◽  
Parasitoid Wasp ◽  
Control Agent ◽  
Douglas Fir ◽  
Seed Predator ◽  
High Level

Douglas-fir seed chalcid (DFSC) Megastigmus spermotrophus, a small (3 mm long) host-specific seed-predatory wasp, was accidentally introduced into New Zealand in the 1920s. Concern over DFSC reducing Douglas-fir seed production in New Zealand led to an attempt at biocontrol in 1955 with the release, but failed establishment, of the small (2.5 mm long) parasitoid wasp, Mesopolobus spermotrophus. We investigated why DFSC causes little destruction of Douglas-fir seed in New Zealand (usually <20%) despite the apparent absence of major natural enemies. Douglas-fir seed collections from 13 New Zealand sites yielded the seed predator (DFSC) but also potential parasitoids, which were identified using morphology and partial COI DNA sequencing. DFSC destroyed only 0.15% of Douglas-fir seed. All parasitoids were identified as the pteromalid wasp, Mes. spermotrophus, the host-specific biocontrol agent released in 1955. Total parasitism was 48.5%, but levels at some sites approached 90%, with some evidence of density-dependence. The discovery of the parasitoid Mes. spermotrophus could indicate that the biocontrol agent released in 1955 did establish after all. Alternatively, Mes. spermotrophus could have arrived accidentally in more recent importations of Douglas-fir seed. The high level of parasitism of DFSC by Mes. spermotrophus is consistent with DFSC being under successful biological control in New Zealand. Suppression of DFSC populations will benefit commercial Douglas-fir seed production in New Zealand, but it also represents the likely loss of a potential biological control agent for wilding Douglas-fir.

Promotion of cone and seed production in grafted and seedling Douglas-fir seed orchards by application of gibberellin A4/7 mixture

1980 ◽  
Vol 10 (4) ◽  
pp. 464-469 ◽  
Author(s):  
Stephen D. Ross ◽  
Richard P. Pharis ◽  
J. C. Heaman
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
Douglas Fir ◽  
Adjunct Treatment ◽  
Seed Cone ◽  
Marked Enhancement ◽  
Napthaleneacetic Acid ◽  
Low Levels ◽  
Effective Adjunct ◽  
Filled Seeds

Both 4-year-old grafts and 6-year-old seedlings of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were induced to flower, and the production of seed cones and filled seeds was significantly enhanced by branch applications of gibberellin A4/7 (GA4/7) mixture.For 6-year-old seedlings, when pooled over all levels of the auxin, napthaleneacetic acid (NAA), seed cone bud differentiation, and number of filled seeds per treatment branch tended to be enhanced by GA3, GA5, and GA9, relative to controls. A more marked enhancement (although still not significant) in number of filled seeds per treatment branch was noted for GA3, GA5, and GA9 when applied in combination with GA4/7, relative to GA4/7 alone. The combination of GA9 + GA4/7 significantly increased the number of seed cone buds differentiated, relative to GA4/7 alone. Low levels of NAA, pooled over all GA treatments, significantly increased the number of seed cones per branch at maturity, and tended to increase both the number of seed cone buds differentiated and filled seeds per branch.Girdling, an effective adjunct treatment for promoting flowering, reduced filled seeds per cone for grafts, but had no effect on seedlings. Neither cone abortion nor seed set was affected by the hormone treatments, although there was a tendency in the seedlings for NAA to reduce cone abortion and increase filled seeds per cone. Seed from GA-induced cones germinated equally as well as that from controls. For grafts, GA treatments resulted in a 500% increase in per-branch yield of filled seeds; for seedlings, increases of 250 to 600% were noted.

A PARTIAL LIFE TABLE FOR THE DOUGLAS-FIR CONE MOTH, BARBARA COLFAXIANA (LEPIDOPTERA: OLETHREUTIDAE)

1977 ◽  
Vol 109 (7) ◽  
pp. 943-951 ◽  
Author(s):  
T. Evan Nebeker
Keyword(s):  
Life Table ◽  
Seed Production ◽  
Critical Factor ◽  
Douglas Fir ◽  
National Forest ◽  
Production Area ◽  
Critical Age

AbstractA population of the Douglas-fir cone moth, Barbara colfaxiana (Kft.), was studied on the Buckhead Seed Production Area, Lowell Ranger District, Willamette National Forest, Oregon, during 1971. Factors contributing to the mortality of B. colfaxiana are presented in a partial life table and discussed. The egg – instar I was identified as the critical age interval and resinosis the critical factor.

Seedfall in a young-growth Douglas-fir stand: 1950–1978

1982 ◽  
Vol 12 (2) ◽  
pp. 249-254 ◽  
Author(s):  
Donald L. Reukema
Keyword(s):  
Seed Production ◽  
Douglas Fir ◽  
The Other ◽  
Young Growth ◽  
Number Of Seeds

A 29-year record of seedfall in thinned and unthinned portions of a Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand, spanning ages 39 through 68, reveals annual seed production from no seeds to about 3 million per hectare. For the nine largest crops, annual seedfall in the best seed-producing thinning treatment included at least 100 000 filled seed per hectare. The first of these nine crops was in 1950; the other eight occurred at 1- to 4-year intervals beginning with 1959. For the nine largest crops, the proportion of seeds filled averaged 45% and ranged from 30 to 54%. Typically, about two-thirds of the seed fell by mid-December; but for two of the three largest crops, time of seed shedding was greatly delayed. Thinning substantially increased the number of seeds produced in some years following thinning but the effect was not lasting. There was little or no effect of thinning on the proportion of seed filled or timing of seed dissemination.

DISTRIBUTION AND IMPACT OF LEPTOGLOSSUS OCCIDENTALS HEIDEMANN (HEMIPTERA: COREIDAE) IN SEED ORCHARDS IN BRITISH COLUMBIA

1996 ◽  
Vol 128 (6) ◽  
pp. 1065-1076 ◽  
Author(s):  
Suzie E. Blatt ◽  
John H. Borden
Keyword(s):  
British Columbia ◽  
Seed Production ◽  
Pseudotsuga Menziesii ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Douglas Fir ◽  
Seed Orchards ◽  
Threshold Levels ◽  
Management Measures ◽  
Leptoglossus Occidentalis

AbstractLeptoglossus occidentalis Heidemann (Hemiptera: Coreidae) is considered to be an important cone and seed pest in seed orchards in British Columbia; however, no impact studies have been done in Canada. Surveys to determine the distribution of L. occidentalis were conducted over a 3-year period in three coastal seed orchards of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, and over a 2-year period in two seed orchards of lodgepole pine, Pinus contorta var. latifolia Engelmann. Leptoglossus occidentalis was found to distribute itself in patches, coinciding with a clonal preference. Seed losses were assessed for 2 years in the coastal Douglas-fir orchards and for 1 year in one lodgepole pine orchard. The percentages of partially filled seed that could have been caused by feeding of L. occidentalis or by a number of other factors were < 5% in coastal Douglas-fir for both 1992 and 1993 and ~14% in lodgepole pine in 1993. Apparently because populations of L. occidentalis were low, there was no correlation between the percentage of partially filled seed and number of insects per tree. Except in unusual circumstances, management measures in Canada are judged not to be necessary as populations of L. occidentalis are consistently below the calculated threshold levels required to cause ≥5% loss in seed production.

Impact of Leptoglossus occidentalis (Hemiptera: Coreidae) on Douglas-Fir Seed Production

2000 ◽  
Vol 93 (5) ◽  
pp. 1444-1451 ◽  
Author(s):  
Sarah L. Bates ◽  
John H. Borden ◽  
Allison R. Kermode ◽  
Robb G. Bennett
Keyword(s):  
Seed Production ◽  
Douglas Fir ◽  
Leptoglossus Occidentalis
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