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.

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.

STUDIES IN FOREST PATHOLOGY: VIII. DECAY OF WESTERN HEMLOCK ON THE QUEEN CHARLOTTE ISLANDS, BRITISH COLUMBIA

1951 ◽  
Vol 29 (5) ◽  
pp. 479-521 ◽  
Author(s):  
R. E. Foster ◽  
A. T. Foster
Keyword(s):  
British Columbia ◽  
Tsuga Heterophylla ◽  
Total Loss ◽  
Western Hemlock ◽  
Site Quality ◽  
Forest Pathology ◽  
Old Growth ◽  
Queen Charlotte Islands ◽  
Dead Trees ◽  
Understory Trees

An investigation of western hemlock (Tsuga heterophylla (Raf.) Sarg.) on the Queen Charlotte Islands, British Columbia, has shown that decay losses in old-growth stands are appreciable, amounting to 13.9, 8.0, and 10.7% of the gross volume of Grades 1, 2, and 3 logs respectively. Total loss, including dead trees, amounted to 25.5% of the gross volume. Twenty-seven decay-producing fungi have been isolated. The most important of these are Fomes pinicola (Sw.) Cke., F. pini (Thore) Lloyd, F. annosus (Fr.) Cke., and Polyporus sulphureus Bull. ex Fr. Echinodontium tinctorium E. & E. apparently does not occur in the region. Scars provided the most frequent, and roots the most important, avenue of entrance for decay. The logs of 2318 western hemlock were analyzed in detail. Decay was found to increase progressively with diameter, age, and decreasing site quality. Maximum net periodic increment was reached between 350 and 400 years of age and between 35 and 40 in. in diameter. Color of bark was found to provide an added indication of tree maturity. Understory trees were found to give a substantial yield of sound wood.

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.

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.

Modeling the incidence and severity of hemlock dwarf mistletoe in 110-year-old wind-disturbed forests in Southeast Alaska

1998 ◽  
Vol 28 (10) ◽  
pp. 1501-1508 ◽  
Author(s):  
L M Trummer ◽  
P E Hennon ◽  
E M Hansen ◽  
P S Muir
Keyword(s):  
Basal Area ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Managed Forests ◽  
Coastal Forests ◽  
Dwarf Mistletoe ◽  
Infection Level ◽  
Southeast Alaska ◽  
Preliminary Validation

Amodel was developed to predict the severity of dwarf mistletoe (Arceuthobium tsugense (Rosendahl) G.N. Jones) in western hemlock trees (Tsuga heterophylla (Raf.) Sarg.) that developed within forests of Southeast Alaska that experienced near-catastrophic windthrow in the late 1800s. The model suggests that the degree of dwarf mistletoe severity on western hemlock trees was significantly and positively correlated with levels of dwarf mistletoe infection and basal area (m2/ha) in large and small residual trees that survived the wind disturbance. No significant relationships were found between severity level and any other factors, including site productivity, density of coexisting Sitka spruce (Picea sitchensis (Bong.) Carr.), or slope. The model demonstrates the overriding importance of infected residual trees to predict future severity of dwarf mistletoe; greater size and infection level of residual trees results in greater dwarf mistletoe levels on regenerating hemlock crop trees. The model, derived from 76 plots on Kuiu Island, was tested in 18 plots on Chichagof Island, providing a preliminary validation. Slower rates of dwarf mistletoe spread and intensification in forests of southeastern Alaska, as compared with similar coastal forests south of Alaska, provide an opportunity for managers to manipulate the parasite to desired levels in managed forests.

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.

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.

Impact of dwarf mistletoe on the growth of western hemlock trees having different patterns of suppression and release

1985 ◽  
Vol 15 (4) ◽  
pp. 665-668 ◽  
Author(s):  
A. J. Thomson ◽  
R. I. Alfaro ◽  
W. J. Bloomberg ◽  
R. B. Smith
Keyword(s):  
Volume Growth ◽  
Severe Infection ◽  
Vancouver Island ◽  
Western Hemlock ◽  
Dwarf Mistletoe ◽  
Area Sampling ◽  
The Impact ◽  
Site Variability

The impact of dwarf mistletoe on the volume growth of western hemlock was evaluated in trees from five locations on northeast Vancouver Island. Within each area, sampling was designed to minimize the effects of site variability. However, differences in age and in patterns of suppression and release between infection classes were observed in some stands. Growth was corrected for these differences by subtracting the suppression core and by making comparisons at equivalent ages. Volume losses associated with dwarf mistletoe infection were higher than reported in our previous studies in other areas, averaging 23 and 39% with moderate and severe infection levels, respectively.

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