The Rate of Upward Advance and Intensification of Dwarf Mistletoe on Immature Western Hemlock

1972 ◽  
Vol 2 (3) ◽  
pp. 313-316 ◽  
Author(s):  
K. S. Richardson ◽  
B. J. van der Kamp
Keyword(s):  
British Columbia ◽  
Height Growth ◽  
Western Hemlock ◽  
Dwarf Mistletoe ◽  
Rate Of Spread ◽  
History Of ◽  
Dense Stand ◽  
Individual Trees ◽  
Crown Closure

The rate of upward advance and intensification of dwarf mistletoe on immature coastal western hemlock were determined by reconstructing the infection history of individual trees from data on age, height above ground, and sex of mistletoe infections present at the time of observation. The vertical rate of spread was 30 ± 4 cm/year in a dense stand (750 trees per hectare, 19 m in height) and 65 ± 4 cm/year in an open stand (250 trees per hectare, 26 m in height). This compares with height growth of the trees of 33 and 58 cm/year in the two stands, respectively. The number of new infections per year increased logarithmically with time, doubling roughly every 4 years. An asymtotic stabilization of the rate of intensification over the last 6 years probably reflects crown closure. The results suggest that dwarf mistletoe may not be a serious threat to thrifty, immature, dense, coastal hemlock stands in southern British Columbia, unless such stands are overtopped by infected residual trees.

Growth patterns in a young western hemlock plantation infested with dwarf mistletoe

1983 ◽  
Vol 13 (5) ◽  
pp. 972-978 ◽  
Author(s):  
A. J. Thomson ◽  
R. B. Smith
Keyword(s):  
Root Systems ◽  
Height Growth ◽  
Growth Patterns ◽  
Western Hemlock ◽  
Height Increment ◽  
Relative Height ◽  
Dwarf Mistletoe ◽  
Diameter Increment ◽  
Breast Height ◽  
Individual Trees

Relative height and diameter values of 22-year-old western hemlock trees (Tsugaheterophylla (Raf.) Sarg.) were normally distributed, with a constant standard deviation from year to year. Ranking of individual trees in the distribution changed with time, presumably because the root systems encountered successively more favourable or unfavourable microsites. Competition effects were detectable on height and diameter at breast height (dbh), although these effects were considerably masked by the microsite effect. Dwarf mistletoe (Arceuthobiumtsugense (Rosendahl) G. N. Jones) effects were detectable on height growth, but not dbh growth. Height increment in a particular year varied in a pattern similar to February precipitation, while diameter increment varied in a pattern similar to March–May precipitation. This may account for the observation that the degree of correlation of height and diameter increments in a particular year varied from low to high.

Field evaluation of ecological differentiation of dwarf mistletoe on shore pine and western hemlock

1976 ◽  
Vol 6 (2) ◽  
pp. 225-228 ◽  
Author(s):  
R. B. Smith ◽  
E. F. Wass
Keyword(s):  
British Columbia ◽  
Field Evaluation ◽  
Field Studies ◽  
Western Hemlock ◽  
Lake Area ◽  
Dwarf Mistletoe ◽  
Varied Composition ◽  
Coastal British Columbia ◽  
Ecological Races ◽  
Shore Pine

Hemloclc dwarf mistletoe (Arcenthobiiuntsugense (Rosend.) G. N. Jones) principally infects western hemlock (Tsugaheteropliylla (Raf.) Sarg.), but it is also damaging to shore pine (Pinuscontorta Dougl. ex Loud.) growing in coastal British Columbia. Stands of varied composition were studied in the Home Lake area of Vancouver Island to compare the levels of infection in shore pine and western hemlock. Infection of shore pine occurred whether or not infected hemlock trees were present in the stand. Observations and measurements from these field studies support indications from earlier artificial inoculation trials that two ecological races of A. tsugense exist.

Development of dwarf mistletoe in western hemlock regeneration in southeast Alaska

1982 ◽  
Vol 12 (3) ◽  
pp. 482-488 ◽  
Author(s):  
Charles G. Shaw III
Keyword(s):  
British Columbia ◽  
Disease Control ◽  
Control Strategies ◽  
Severe Infection ◽  
Host Tissue ◽  
Western Hemlock ◽  
Dwarf Mistletoe ◽  
Local Conditions ◽  
Southeast Alaska ◽  
Understory Trees

Western hemlock (Tsugaheterophylla (Raf.) Sarg.) regenerated within 9.14 m of old-growth hemlock severely infected with dwarf mistletoe, Arceuthobiumtsugense ((Rosendahl) G.N. Jones), and left standing on cutover sites in southeast Alaska were felled and examined for infection. The percentage of understory trees infected among the 3429 examined averaged 9, 7, 5, and 17, respectively, in 17-, 19-, 35-, and 43-year-old stands. Ninety-two percent of all infections in the 17-, 19-, and 35-year-old stands were alive, but only 51% were alive in the 43-year-old stand. In all stands few trees had more than two live infections and few had any infections in their middle or upper crown. In all stands, advanced regeneration was more frequently infected and accounted for a significantly greater proportion of crop trees than new reproduction. A significantly higher proportion of hemlock crop trees were infected than non crop trees, but the number of infections on crop trees was consistently low. Most infections were established on host tissue 5 years or younger, but tissue up to 13 years old was infected. At a comparable age, young stands in Alaska appear to be less severely affected by A. tsugense than similar stands in Washington, Oregon, and British Columbia. Disease control strategies, developed for stands experiencing more severe infection intensities than those now known to prevail in southeast Alaska, will require modification to meet local conditions.

Epidemiology of dwarf mistletoe in western hemlock stands in south coastal British Columbia

1985 ◽  
Vol 15 (5) ◽  
pp. 909-913 ◽  
Author(s):  
R. I. Alfaro ◽  
W. J. Bloomberg ◽  
R. B. Smith ◽  
A. J. Thomson
Keyword(s):  
British Columbia ◽  
Spatial Distribution ◽  
Distribution Pattern ◽  
Tree Mortality ◽  
Infection Intensity ◽  
Western Hemlock ◽  
Intensity Level ◽  
Dwarf Mistletoe ◽  
Infection Index ◽  
Coastal British Columbia

Surveys of seven western hemlock (Tsugaheterophylla) stands in south coastal British Columbia using fixed-radius plots assessed dwarf mistletoe (Arceuthobiumtsugense) infection intensity level and spatial distribution patterns. Regression analysis indicated a close relationship between the plot infection index (average dwarf mistletoe rating of trees in a plot) and the percentage of infected trees. Plot infection index reached 4.0 when all trees in a plot were infected. Infected trees were either associated with widely spaced infection centers or were more or less evenly distributed throughout the stand. Spatial distribution pattern and spread rate were related to (i) the severity and distribution pattern of the initial inoculum sources, (ii) the manner of stand regeneration and resulting stand structure, and (iii) the presence of barriers to spread such as a high nonhost component and drastic slope increases. Tree mortality from dwarf mistletoe averaged 0.6% (range, 0–1.8%) and was much lower than mortality from other causes. On average, 9.3% of the trees had large dwarf mistletoe caused swellings on the lower third of the bole.

FUNGI FROM DWARF MISTLETOE INFECTIONS IN WESTERN HEMLOCK

1966 ◽  
Vol 44 (5) ◽  
pp. 597-604
Author(s):  
J. A. Baranyay
Keyword(s):  
British Columbia ◽  
Western Hemlock ◽  
Coastal Forest ◽  
Dwarf Mistletoe ◽  
Epicoccum Nigrum ◽  
Fungi Imperfecti

Nine ascomycetes and two fungi imperfecti were found associated with cankers on branch swellings caused by western hemlock dwarf mistletoe, Arceuthobium campylopodum Engelm. forma tsugensis Gill, in an investigation in the coastal forest of British Columbia. One ascomycete is described as Durandiella tsugae sp. nov. The following fungi are discussed: Lachnellula agassizii (Berk, and Curt.) Dennis, Caliciopsis pseudotsugae Fitzp., Capnodium spongiosum Barr, Durandiella tsugae Baranyay sp. nov., Helotium sp., Lophium mytilinum (Pers.) Fries, Mytilidion tortile (Schw.) Ell. & Ev. non Sacc, Retinocyclus abietis (Crouan) Groves & Wells, Biatorella resinae (Fr.) Mudd., Epicoccum nigrum Link, and Truncatella truncata (Lév.) Steyaert.

The Relation of Weather to Population Trends of the Black-headed Budworm Acleris variana (Fern.) (Lepidoptera: Tortricidae)

1960 ◽  
Vol 92 (6) ◽  
pp. 401-410 ◽  
Author(s):  
G. T. Silver
Keyword(s):  
British Columbia ◽  
West Coast ◽  
Vancouver Island ◽  
Tsuga Heterophylla ◽  
Population Trends ◽  
Western Hemlock ◽  
Canal Area ◽  
Queen Charlotte Islands ◽  
History Of ◽  
Coastal British Columbia

The history of the black-headed budworm, Acleris variana (Fern.), in the western hemlock (Tsuga heterophylla (Raf.) Sarg.) forests of coastal British Columbia is one of recurring cycles of outbreaks. The latest cycle occurred from 1952 to 1957 and was represented by three main outbreaks in the Portland Canal area from Prince Rupert to Stewart, the Queen Charlotte Islands, and on northern Vancouver Island. Previous to this, groups of West Coast outbreaks were recorded from 1940 to 1945, and from 1927 to 1931 (Prebble and Graham, 1945a).

Canker of Dwarf Mistletoe Swellings on Western Hemlock Caused by Nectriafuckeliana var. macrospora

1973 ◽  
Vol 3 (1) ◽  
pp. 71-74 ◽  
Author(s):  
A. Funk ◽  
R. B. Smith ◽  
J. A. Baranyay
Keyword(s):  
British Columbia ◽  
Western Hemlock ◽  
Artificial Inoculation ◽  
Dwarf Mistletoe

Nectriafuckeliana Booth var. macrospora (Wr.) Booth was commonly associated with open, resinous cankers of dwarf mistletoe swellings of western hemlock (Tsugaheterophylla (Raf.) Sarg.) in British Columbia, Canada. Pathogenicity of the fungus was proved by artificial inoculation and reisolation from cankered tissues. Cankers substantially reduced dwarf mistletoe reproduction.

Potebniamyces gallicola n.sp., from dwarf mistletoe infections in western hemlock

1981 ◽  
Vol 59 (9) ◽  
pp. 1610-1612 ◽  
Author(s):  
A. Funk ◽  
R. B. Smith
Keyword(s):  
British Columbia ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Dwarf Mistletoe

Potebniamyces gallicola n.sp. is described from dwarf mistletoe galls (Arceuthobium tsugense (Rosendahl) G. N. Jones) on western hemlock (Tsuga heterophylla (Raf.) Sarg.), growing in British Columbia, Canada. It has a typical Phacidiopycnis anamorph which is produced both in the host and in culture, as well as hyphal "bud" conidia produced in fresh agar cultures.

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