The effects of male and female Arceuthobium americanum (lodgepole pine dwarf mistletoe) infection on the relative positioning of vascular bundles, starch distribution, and starch content in Pinus contorta var. latifolia (lodgepole pine) needles

Botany ◽  
2008 ◽  
Vol 86 (5) ◽  
pp. 539-543 ◽  
Author(s):  
Aditya Chhikara ◽  
Cynthia M. Ross Friedman
Keyword(s):  
Pinus Contorta ◽  
Biochemical Analysis ◽  
Lodgepole Pine ◽  
Starch Content ◽  
Periodic Acid ◽  
Vascular Bundles ◽  
Dwarf Mistletoe ◽  
Needle Anatomy ◽  
Arceuthobium Americanum

The lodgepole pine dwarf mistletoe, Arceuthobium americanum Nutt. ex Engelm., is a dioecious angiosperm that parasitizes conifers in western Canadian forests, causing significant yearly timber loss. A striking consequence of dwarf mistletoe infection is a marked reduction in the size of the needles located distal to the infection. The purpose of this work was to use microscopy, cytochemistry, and biochemical analysis to determine whether this reduction was associated with changes in needle anatomy and (or) starch content. Furthermore, we wanted to investigate whether these potential changes were affected by the gender of the infecting dwarf mistletoe plant. We developed a ratio (R) that evaluated the position of the two vascular bundles relative to the size of the needle, and found that bundles from male-infected trees were positioned significantly closer together than in needles from female-infected or uninfected trees (p < 0.05). Using the periodic acid – Schiff’s (PAS) reaction for cytochemical identification of starch in situ, we determined that needles from uninfected trees had abundant starch grains compared with needles from infected trees; colourimetric analysis for total starch content corroborated our PAS data. This is the first report of this phenomenon in lodgepole pine, and further supports the use of needle characteristics to assess tree health.

Relationships between dwarf mistletoe and the canopy structure of an old-growth lodgepole pine forest in central Oregon

2003 ◽  
Vol 33 (6) ◽  
pp. 997-1009 ◽  
Author(s):  
R C Godfree ◽  
R O Tinnin ◽  
R B Forbes
Keyword(s):  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Abiotic Factors ◽  
Canopy Structure ◽  
Structural Diversity ◽  
Conifer Forest ◽  
Dwarf Mistletoe ◽  
Arceuthobium Americanum ◽  
Canopy Volume ◽  
The Vertical Distribution

The relationships between abundance of dwarf mistletoe (Arceuthobium americanum Nutt.) and the canopy structure of stands of lodgepole pine (Pinus contorta var. murrayana (Grev. & Balf.) Engelm.) were investigated in the central Oregon pumice zone. Foliage height profiles were generated for stands containing light, moderate, and heavy infestations of A. americanum, and the vertical distribution of P. contorta foliage was modeled using the Weibull distribution. Stand-level changes in the Weibull parameters σ (scale parameter) and c (shape parameter) as well as other canopy indices were related to the abundance of A. americanum, the density of competing tree species, and stand-level abiotic factors. Foliage intercept diagrams showed that heavily infested stands had more foliage in the lower canopy and less in the upper canopy than lightly infested stands, but that total canopy height and canopy volume were similar regardless of infestation level. We also found that dwarf mistletoe abundance was strongly related to σ (r = –0.74, p < 0.001) and c (r = –0.54, p < 0.0001). Since heavily infested stands contained fewer large but many more small P. contorta than lightly infested stands, we conclude that A. americanum causes the canopy of infested stands to change, in part, by inducing demographic changes in populations of the host tree. These results illustrate the significant effects that dwarf mistletoes can have on the structural diversity of conifer forest communities and have important consequences for the conservation and management of these systems.

Aerial Application of Ethephon is ineffective in Controlling Lodgepole Pine Dwarf Mistletoe

1989 ◽  
Vol 4 (1) ◽  
pp. 27-28 ◽  
Author(s):  
Kathryn Robbins ◽  
David W. Johnson ◽  
Frank G. Hawksworth ◽  
Thomas H. Nicholls
Keyword(s):  
Plant Growth ◽  
Growth Regulator ◽  
Plant Growth Regulator ◽  
Direct Contact ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Aerial Application ◽  
Dwarf Mistletoe ◽  
Arceuthobium Americanum

Abstract Ethephon is an ethylene-releasing plant growth regulator that induces abscission of dwarf mistletoe (Arceuthobium americanum) aerial shoots on lodgepole pine (Pinus contorta) when applied from the ground. However, ethephon was not effective when applied by helicopter in two Colorado tests, because it did not come into enough direct contact with dwarf mistletoe shoots to induce abscission. West. J. Appl. For. 4(1):27-28, January 1989.

scholarly journals Effects of Lodgepole Pine Dwarf Mistletoe, Arceuthobium americanum, on Jack Pine, Pinus banksiana, Growth in Manitoba

2004 ◽  
Vol 118 (4) ◽  
pp. 595 ◽  
Author(s):  
Brock Epp ◽  
Jacques C. Tardif
Keyword(s):  
Pinus Banksiana ◽  
Growth Models ◽  
Lodgepole Pine ◽  
Wood Quality ◽  
Basal Area ◽  
Jack Pine ◽  
Dwarf Mistletoe ◽  
Tree Form ◽  
Arceuthobium Americanum ◽  
Pine Trees

The Lodgepole Pine Dwarf Mistletoe (Arceuthobium americanum Nutt. ex Engelm.) is an important pathogen of Jack Pine (Pinus banksiana Lamb.). Dwarf Mistletoe alters tree form, suppresses growth, and reduces volume and overall wood quality of its host. Stem analysis and a 3-parameter logistic regression model were used to compare the growth of heavily and lightly to non infected Jack Pine trees. At the time of sampling, no significant reduction in diameter at breast height and basal area were observed in heavily infected trees. However, a significant reduction in height and volume and an increase in taper were observed in heavily infected trees. Growth models predicted a 21.1% lower basal area, 23.4% lower height and 42.1% lower volume by age 60 for the high infection group.

Vegetative and floral development in the pistillate plant of Arceuthobium americanum (lodgepole pine dwarf mistletoe): an environmental scanning electron microscopy study of its phenology and shoot organization

Botany ◽  
2017 ◽  
Vol 95 (3) ◽  
pp. 337-346
Author(s):  
Dylan J. Ziegler ◽  
Cynthia Ross Friedman
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lodgepole Pine ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Dwarf Mistletoe ◽  
Three Generations ◽  
Arceuthobium Americanum ◽  
Female Flowers ◽  
Scanning Electron

Dwarf mistletoes (DM), genus Arceuthobium, are dioecious parasitic flowering plants having prolonged life cycles lasting six years, culminating with explosive discharge of the single seed from the fruit. Arceuthobium americanum Nutt. ex Engelm., the lodgepole pine dwarf mistletoe, infects lodgepole pine (Pinus contorta subsp. latifolia (Engelm.) Critchfield) in western North America, compromising the forest economy. Highly reduced flowers appear no later than two years following shoot development, with female flowers appearing and persisting for over two years. Development of the pistillate plant, including initiation of floral growth, has not been fully explored. Here, we used environmental scanning electron microscopy to demark phenological waypoints throughout the pistillate plant’s development. As successive crops of female flowers emerged every year, up to three generations of flowers/fruit could be found on a single shoot in late summer; we used these three generations to delineate specific developmental stages. Vegetative shoots could initiate growth at any time within the growing season, could assume a terminal position, could also adopt sympodial branching, but were never whorled or adventitious. Floral branches, however, could initiate adventitiously from older nodes in a whorled pattern, and could house flowers/fruits of any generation. Vegetative and floral units were structurally homogeneous, suggesting shared developmental pathways.

The effects of dwarf mistletoe, witches' brooms, stand structure, and site characteristics on the crown architecture of lodgepole pine in Oregon

2002 ◽  
Vol 32 (8) ◽  
pp. 1360-1371 ◽  
Author(s):  
R C Godfree ◽  
R O Tinnin ◽  
R B Forbes
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Soil Type ◽  
Pinus Contorta ◽  
Stand Structure ◽  
Lodgepole Pine ◽  
Stand Density ◽  
Dwarf Mistletoe ◽  
Site Characteristics ◽  
Crown Dimensions

We investigated the importance of lodgepole pine dwarf mistletoe (Arceuthobium americanum Nutt.) in determining the height to crown top (HCT), height to crown base (HCB), and live crown ratio (LCR) of 2025 lodgepole pine (Pinus contorta var. murrayana (Grev. & Balf.) Engelm.) growing over a 24-km2 study site in central Oregon. We compared the effects of infection and associated witches' brooms with those of site topography, soil type, shrub cover, stand density, and the abundance of mature ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws). using multiple regression and path analysis. The density of dominant-size P. contorta was consistently the most important factor influencing HCT, HCB, and LCR across the study site. In dense stands, trees tended to have elevated crown bases due to self-pruning and, hence, lower values of LCR. Dwarf mistletoe and related witches' brooms uniquely explained 6.9% of the variance in LCR, which was close to that of dominant P. contorta (7.1%) and more than that of soil type (3.0%), but explained only 2.6% of the variance in HCB, which was less than that of dominant P. contorta (6.5%) and soil type (4.6%). Regression models suggest that heavily infected trees should be 18% shorter and have crown bases 37% lower than uninfected trees, while moderately infected trees should have an LCR over 20% larger than that of uninfected and heavily infected trees. We also found that the largest 25 heavily infected trees sampled were approximately 19% shorter and 11–13% smaller in diameter than the largest 25 uninfected trees. The results suggest that dwarf mistletoe can be an important factor in determining the crown dimensions of P. contorta but that these effects may be interpreted only in the context of site characteristics and stand structure.

Life cycle of Arceuthobium americanum on Pinus banksiana based on inoculations in Edmonton, Alberta

2006 ◽  
Vol 36 (4) ◽  
pp. 1006-1016 ◽  
Author(s):  
J P Brandt
Keyword(s):  
Life Cycle ◽  
Pinus Banksiana ◽  
Lodgepole Pine ◽  
Jack Pine ◽  
Western Canada ◽  
Dwarf Mistletoe ◽  
Arceuthobium Americanum ◽  
Pine Trees

While lodgepole pine dwarf mistletoe, Arceuthobium americanum Nutt. ex Engelm., is one of the most damaging pests of jack pine (Pinus banksiana Lamb.) in western Canada, no studies have examined the life cycle of this parasite in this pathosystem. Twenty-five jack pine trees in a plantation in Edmonton, Alberta, were inoculated with seeds of A. americanum in the fall of 1998 and 1999; these inoculants were monitored until the dwarf mistletoe plants that arose completed their life cycle. Ninety-two percent of inoculated seeds overwintered on their host. Seventy percent of these seeds germinated, mostly in May. Of these germinants, 69% developed holdfasts. Sixty-eight percent of germinants that developed holdfasts infected their host and produced shoots, primarily between July and August in the second season after inoculation. Of the 56 plants that developed from the 175 inoculations, 34 were pistillate plants and 19 were staminate plants, and 3 immature plants died because the host branch died. Pistillate plants flowered significantly earlier than staminate plants (4.1 vs. 4.7 years). Most pistillate plants produced seed in the fifth year, although one plant produced seed in 4 years. Thus, A. americanum probably has a 5-year life cycle on jack pine.

Ectomycorrhizas of lodgepole pine (Pinus contorta) seedlings originating from seed in southwestern Alberta cut blocks

1998 ◽  
Vol 76 (2) ◽  
pp. 213-217 ◽  
Author(s):  
S M Bradbury
Keyword(s):  
Seed Germination ◽  
Pinus Contorta ◽  
Host Plants ◽  
Lodgepole Pine ◽  
Sampling Time ◽  
Pine Seedlings ◽  
Seedling Roots ◽  
Fungal Associates ◽  
One Year

Lodgepole pine (Pinus contorta Dougl. ex Loud.) seedlings, originating from seed in three southwestern Alberta cut blocks, were sampled to identify their ectomycorrhizal associates. Fourteen ectomycorrhizal taxa were identified, 10 were common to all three cut blocks, and 12 to two cut blocks. Individual seedlings were colonized by two fungal associates on average and never had more than six fungal associates at one sampling time. Total percent colonization of seedling roots was greater than 50% one year after seed germination and greater than 90% two years after seed germination. Species richness increased throughout the course of the study; however, all but two ectomycorrhizal taxa were found in mature forests nearby. Typical late-stage ectomycorrhizal fungi colonized regenerating lodgepole pine seedlings in the absence of refuge host plants; therefore, either these fungi remained viable in situ between harvesting and regeneration or they migrated back into the cut block once revegetation was initiated.Key words: lodgepole pine seedlings, ectomycorrhiza, percent relative abundance, Alberta cut blocks.

Fire and dwarf mistletoe (Viscaceae: Arceuthobium species) in western North America: contrasting Arceuthobium tsugense and Arceuthobium americanum

Botany ◽  
2017 ◽  
Vol 95 (3) ◽  
pp. 231-246 ◽  
Author(s):  
David C. Shaw ◽  
Michelle C. Agne
Keyword(s):  
North America ◽  
Pinus Contorta ◽  
Forest Disturbance ◽  
Fire Suppression ◽  
Forest Composition ◽  
Western North America ◽  
Dwarf Mistletoe ◽  
Arceuthobium Americanum ◽  
Primary Determinant ◽  
Composition Structure

Dwarf mistletoes (Viscaceae: Arceuthobium spp.) and fire interact in important ways in the coniferous forests of western North America. Fire directly affects dwarf mistletoes by killing the host, host branch, or heating/smoking the aerial shoots and fruits. Fire is a primary determinant of dwarf mistletoe distribution on the landscape, and time since fire controls many aspects of dwarf mistletoe epidemiology. Conversely, dwarf mistletoes can influence fire by causing changes in forest composition, structure, and fuels. Prescribed fire is important for management of dwarf mistletoes, while fire suppression is thought to have increased dwarf mistletoe abundance in western forests. Two dwarf mistletoes are compared in order to illustrate fire interactions in Oregon and Washington, USA: Arceuthobium americanum Nutt. ex Engelm. (lodgepole pine dwarf mistletoe) and Arceuthobium tsugense (Rosendahl)(western hemlock dwarf mistletoe). Arceuthobium persists on the landscape where the host is not killed by fire. Arceuthobium americanum spreads directly into the regenerating Pinus contorta Dougl. ex Loud., while A. tsugense persists in refugia for 200 years or more following fire. Host successional status is a driver of fire – dwarf mistletoe interactions, but forest disturbance agents also play a role. Given the importance of these interactions to the ecology of fire-prone forests, dwarf mistletoes warrant inclusion in disturbance ecology research.

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