scholarly journals Pathogenicity and Virulence of Pythium Species Obtained from Forest Nursery Soils on Douglas-Fir Seedlings

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 744-748 ◽  
Author(s):  
Jerry E. Weiland ◽  
Bryan R. Beck ◽  
Anne Davis
Keyword(s):  
Pseudotsuga Menziesii ◽  
Seedling Survival ◽  
The United States ◽  
Douglas Fir ◽  
Tree Seedlings ◽  
Pythium Species ◽  
Forest Nursery ◽  
Damping Off ◽  
Greenhouse Study ◽  
Forest Nurseries

Pythium species are common soilborne oomycetes that occur in forest nursery soils throughout the United States. Numerous species have been described from nursery soils. However, with the exception of P. aphanidermatum, P. irregulare, P. sylvaticum, and P. ultimum, little is known about the potential for other Pythium species found in nursery soils to cause damping-off of tree seedlings. A greenhouse study was conducted to evaluate the pathogenicity and virulence of 44 Pythium isolates representing 16 species that were originally recovered from soil at three forest nurseries in Washington and Oregon. Seeds of Douglas-fir (Pseudotsuga menziesii) were planted into soil infested with each of the isolates. Seedling survival, the number of surviving seedlings with necrotic root lesions, and taproot length were evaluated 4 weeks later. Responses of Douglas-fir to inoculation varied significantly depending on Pythium species and isolate. Eight species (P. dissotocum, P. irregulare, P. aff. macrosporum, P. mamillatum, P. aff. oopapillum, P. rostratifingens, P. sylvaticum, and P. ultimum var. ultimum) significantly reduced the number of surviving seedlings compared to the noninoculated treatment. However, all Pythium species caused a greater percentage of seedlings to develop root lesions (total mean 40%) than was observed from noninoculated seedlings (17%). Taproot length varied little among Pythium treatments and was not a useful character for evaluating pathogenicity. Results confirm the ability of P. irregulare, P. mamillatum, and P. ultimum var. ultimum to cause damping-off of Douglas-fir seedlings, and are indicative that other species such as P. dissotocum, P. aff. macrosporum, P. aff. oopapillum, P. rostratifingens, and P. sylvaticum may also be responsible for seedling loss.

scholarly journals Influence of Isolation Method on Recovery of Pythium Species from Forest Nursery Soils in Oregon and Washington

Plant Disease ◽  
2011 ◽  
Vol 95 (5) ◽  
pp. 547-553 ◽  
Author(s):  
Jerry E. Weiland
Keyword(s):  
Pacific Northwest ◽  
The United States ◽  
Pythium Species ◽  
Forest Nursery ◽  
Isolation Method ◽  
Species Identity ◽  
The Pacific ◽  
Forest Nurseries ◽  
Species Richness And Abundance ◽  
Isolated Species

Pythium species are common damping-off pathogens that can cause stunting, chlorosis, and death of conifer seedlings in the Pacific Northwest (PNW) region of the United States. Despite the prevalence and importance of these pathogens in forest nurseries, relatively little is known about the identity of Pythium species associated with forest nursery soils in Washington and Oregon. A limited number of studies have reported P. aphanidermatum, P. irregulare, P. mamillatum, and P. ultimum as the predominant species in the PNW, but most studies of this genus in forest nurseries have not reported Pythium species identity. In an attempt to identify Pythium species associated with forest nursery soils, field surveys were conducted at three forest nurseries (two in Oregon and one in Washington) in 2008 using three isolation methods. Pythium species were isolated by plating soil onto a semiselective medium or by baiting soil with rhododendron leaf disks and Douglas-fir needle segments. One hundred isolates were randomly selected from each isolation method at each nursery (900 isolates total) and identified on the basis of the internal transcribed spacer (ITS) sequence. Nineteen Pythium species were identified during the survey. Species richness and abundance were strongly influenced by both nursery and isolation method. Of the 300 isolates obtained from each nursery, P. irregulare was the most commonly isolated species from nursery A in Washington (65% incidence). P. ‘vipa’ and P. dissotocum were the most commonly isolated species from nurseries B and C in Oregon, respectively (53 and 47% incidence, respectively).

scholarly journals Infection of Select Pinaceae and Cupressaceae Seedlings to Phytophthora pinifolia

2019 ◽  
Vol 20 (2) ◽  
pp. 106-111
Author(s):  
Timothy L. Widmer ◽  
Stephen C. Dodge
Keyword(s):  
United States ◽  
At Risk ◽  
Pseudotsuga Menziesii ◽  
Loblolly Pine ◽  
Pinus Radiata ◽  
Pinus Elliottii ◽  
The United States ◽  
Douglas Fir ◽  
Important Species ◽  
Monterey Pine

Phytophthora pinifolia caused a devastating disease on Monterey pine (Pinus radiata) in Chile. This pathogen has not been reported in the United States, but there is concern should it arrive. There is little information regarding other hosts besides Monterey pine that may be susceptible to this pathogen. In the present study, other potential hosts within the Pinaceae and Cupressaceae were inoculated with zoospores of P. pinifolia and observed for symptoms and infection after 4 weeks. Similar to Monterey pine, knobcone (Pinus attenuata), bishop (P. muricata), and ponderosa (P. ponderosa) pines were highly infectious, whereas several important species such as loblolly pine (P. taeda) and Douglas fir (Pseudotsuga menziesii) showed no infection. P. pinifolia was also not recovered from slash (Pinus elliottii) and eastern white (P. strobus) pines. This study is important because it demonstrates other economically important tree hosts are at risk by P. pinifolia, should it enter the United States.

scholarly journals Characterizing the Utility of the Root-to-Shoot Ratio in Douglas-Fir Seedling Production

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1745
Author(s):  
Rebecca A. Sheridan ◽  
Anthony S. Davis
Keyword(s):  
Seedling Survival ◽  
Douglas Fir ◽  
Tree Seedlings ◽  
Evaluation Tool ◽  
Physiological Basis ◽  
Shoot Ratio ◽  
Wide Variability ◽  
Vital Component ◽  
Root To Shoot Ratio ◽  
The Relationship

Nursery-grown tree seedlings are a vital component of successful restoration and reforestation programs, useful when calls for increased planting for industrial forest management are made, and a tool for climate change mitigation. One of the most extensively planted and studied trees in Western North America is Douglas-fir. Building on that body of work, this review was conducted to identify if the root-to-shoot ratio (root:shoot, R:S), a commonly referred-to metric in reforestation planning, yields meaningful guidance for producing seedlings that are better able to establish across a variety of field conditions. The results indicated that there is wide variability in R:S of nursery-grown seedlings. The relationship between R:S and subsequent root growth and seedling survival varies depending on Douglas-fir variety, seedling stocktypes, and site conditions. The biological and physiological basis for using R:S remains, and likely could be used to enhance seedling quality; however, there is an ongoing need for planning and collaboration between researchers and practitioners to identify how to best deploy this evaluation tool.

Survival and Growth of Douglas-Fir Seedlings with Spot-Spraying, Mulching and Root-Dipping

1986 ◽  
Vol 1 (4) ◽  
pp. 108-111 ◽  
Author(s):  
Chao-Hsiung Tung ◽  
Jim Batdorff ◽  
David R. DeYoe
Keyword(s):  
Pseudotsuga Menziesii ◽  
Seedling Survival ◽  
Growing Season ◽  
Vegetation Management ◽  
Height Growth ◽  
Douglas Fir ◽  
The Third ◽  
Growing Seasons ◽  
Survival And Growth ◽  
Survival Of Seedlings

Abstract Two vegetation management methods, paper mulching and spot-spraying with glyphosate, were combined with a root-dipping treatment, Terra Sorb®, to test effects on seedling survival and height growth on a harsh site in Oregon. Survival of Douglas-fir (Pseudotsuga menziesii) seedlings was significantly higher after the third growing season when competing vegetation had been controlled with mulch or glyphosate during the first two growing seasons. Seedlings retreated with paper mulch and glyphosate before the second growing season had 36 and 25% higher survival than those that were not retreated. None of the seedlings was retreated before the third season; after this season, survival of seedlings treated twice with glyphosate was 26, 23, and 21% higher than seedlings receiving one glyphosate treatment and one or two mulch applications, respectively. There were no differences in seedling height growth among treatments. Rootdipping with Terra Sorb® did not influence survival or growth. West. J. Appl. For. 1:108-111 Oct. 86.

THE OCCURRENCE OF ENDOPHYTIC FUNGI IN DOUGLAS-FIR SEEDLINGS AND SEED

1966 ◽  
Vol 44 (4) ◽  
pp. 413-420 ◽  
Author(s):  
W. J. Bloomberg
Keyword(s):  
British Columbia ◽  
Fusarium Oxysporum ◽  
Pseudotsuga Menziesii ◽  
Endophytic Fungi ◽  
Seed Coat ◽  
Douglas Fir ◽  
Malt Agar ◽  
Root Segments ◽  
Forest Nurseries

Segments taken from the roots and shoots of healthy 1-year-old seedlings of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) collected over a 2-year period from two British Columbia forest nurseries, were surface-sterilized, and incubated on various media. Fungi grew from segments of over 80% of the seedlings, the most frequent being Fusarium oxysporum Schlecht., F. redolens Wr., Mycelium radicis atrovirens, Cylindrocarpon didymum (Hart.) Wollenw., and C. radicicola Wollenw. Fungi were isolated more frequently from the shoot than from the root segments. Isolations from segments with the bark intact were more frequent than from segments that had the bark removed. Seedlings collected in the winter produced more fungi than those collected during the summer. Segments from diseased seedlings and seedlings grown under sterile conditions produced mycofloras which were different from each other and from that of healthy nursery-grown seedlings. Without exception, fungi grew from surface-sterilized seed placed on malt agar and samples from different seedlots had different floras. Stained sections clearly showed hyphae and chlamydospores well within the tissue of roots, shoots, and seed coat.

scholarly journals Twenty-Year Response of Ponderosa Pine (Pinus ponderosa Laws.) to Treatment with Hexazinone in Northeastern Oregon

2009 ◽  
Vol 24 (3) ◽  
pp. 151-156
Author(s):  
Amanda Lindsay ◽  
Paul Oester ◽  
Elizabeth Cole
Keyword(s):  
Pseudotsuga Menziesii ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Seedling Survival ◽  
Douglas Fir ◽  
Individual Tree ◽  
Growth And Survival ◽  
Competing Vegetation ◽  
Plant Associations ◽  
Initial Control

Abstract Chemical control of competing vegetation with hexazinone is a common and effective silvicultural treatment for ensuring ponderosa pine (Pinus ponderosa Laws.) plantation success on dry sites in the western United States, yet few studies document the effect for more than the first few years after planting. This study, re-evaluated 20 years after planting, followed ponderosa pine growth and survival when hexazinone was applied in broadcast and spot treatments for control of competing vegetation. We continued work from the first 5 years after establishment that identified early differences in ponderosa pine seedling survival and growth with treatment. Examination of 20-year trends indicated that individual tree volume and volume per hectare continued to diverge among treatments. The economic differences among treatments may increase as more surviving, faster-growing trees in the broadcast treatments reach higher-value products sooner. Initial control of competing vegetation increased the likelihood of seedling survival and increased tree size after 20 years. Results pertained to ponderosa pine of the Douglas-fir/spiraea (Pseudotsuga menziesii var. glauca Beissn./Spiraea betulifolia Pall.) and Douglas-fir/common snowberry (Pseudotsuga menziesii var. glauca Beissn./Symphoricarpos albus [L.] S. F. Blake) plant associations in northeastern Oregon, but they should apply to similar sites throughout much of the intermountain West.

scholarly journals Sensitivity of Pythium irregulare, P. sylvaticum, and P. ultimum from Forest Nurseries to Mefenoxam and Fosetyl-Al, and Control of Pythium Damping-off

Plant Disease ◽  
2014 ◽  
Vol 98 (7) ◽  
pp. 937-942 ◽  
Author(s):  
Jerry E. Weiland ◽  
Luisa Santamaria ◽  
Niklaus J. Grünwald
Keyword(s):  
Disease Control ◽  
Phosphorous Acid ◽  
Damping Off ◽  
Pythium Irregulare ◽  
Greenhouse Study ◽  
Biological Treatments ◽  
Forest Nurseries ◽  
And Control ◽  
Further Development

Mefenoxam and fosetyl-Al are common fungicides used to supplement disease control of Pythium damping-off and root rot in forest nurseries of the western United States. However, it is unknown whether fungicide-resistant Pythium isolates are present or whether new fungicide and biological treatments might also provide supplemental disease control. Isolates of Pythium irregulare, P. sylvaticum, and P. ultimum from three forest nurseries were evaluated for in vitro sensitivity to mefenoxam and fosetyl-Al. A greenhouse study was also conducted to assess efficacy of fungicide and biological treatments in Douglas-fir (Pseudotsuga menziesii) seedlings inoculated with Pythium dissotocum, P. irregulare, and P. ‘vipa’. P. irregulare was approximately three times less sensitive to mefenoxam (0.20 μg/ml) than P. sylvaticum (0.06 μg/ml) and P. ultimum (0.06 μg/ml), and two resistant isolates of P. ultimum were identified (≥311 μg/ml). All three Pythium spp. were similarly sensitive to fosetyl-Al (1,256 to 1,508 μg/ml) and no resistant isolates were found. In the disease control efficacy trial, both fosetyl-Al and phosphorous acid consistently provided good protection against damping-off caused by P. dissotocum, P. irregulare, and P. ‘vipa’. Other treatments, including mefenoxam, also provided good or intermediate protection but efficacy depended upon which Pythium sp. was used. Growers should consider rotating mefenoxam use with other fungicide chemistries or biological treatments to prevent further development and spread of mefenoxam-resistant isolates.

Seasonal Browsing of Douglas-Fir Seedlings by Sheep

1989 ◽  
Vol 4 (3) ◽  
pp. 73-76 ◽  
Author(s):  
Wayne C. Leininger ◽  
Steven H. Sharrow
Keyword(s):  
Pseudotsuga Menziesii ◽  
Mechanical Damage ◽  
The United States ◽  
Douglas Fir ◽  
Bud Break ◽  
Seedling Height ◽  
Herbaceous Species ◽  
Coast Range ◽  
Sheep Grazing ◽  
Conifer Plantations

Abstract Controlled sheep grazing is being prescribed in the United States and elsewhere for the biological control of unwanted vegetation in regenerating conifer plantations. Efficient use of livestock to control brush and herbaceous species requires a thorough understanding of the potential for damage to the tree crop by the grazing animal. Sheep browsing and mechanical damage to Douglas-fir (Pseudotsuga menziesii) seedlings were evaluated in 1981 and 1982 in the Coast Range of Oregon. Sheep browsing of Douglas-fir was greatest in May, soon after bud break. Little browsing generally occurred during July and August. Percent of study trees with browsed terminal shoots decreased as seedling height increased above 90 cm. Less than 3% of the study trees were trampled or received other mechanical impacts by sheep. Our data suggest that Douglas-fir forests can be grazed by sheep with little or no damage to conifer regeneration, except in younger plantations in spring. Extra care must be exercised, during this season, when grazing plantations that have seedlings with terminal shoots less than 1.2 m in height. West. J. Appl. For. 4(3):73-76, July 1989.

Ectomycorrhizal fungi associated with Arctostaphylos contribute to Pseudotsuga menziesii establishment

1999 ◽  
Vol 77 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Thomas R Horton ◽  
Thomas D Bruns ◽  
V Thomas Parker
Keyword(s):  
Pseudotsuga Menziesii ◽  
Ectomycorrhizal Fungi ◽  
Seedling Survival ◽  
Arbuscular Mycorrhizal ◽  
Douglas Fir ◽  
Soil Core ◽  
Compelling Evidence ◽  
Central Coast ◽  
Vegetation Surveys

Chaparral on the central coast of California can occur as relatively stable patches of ectomycorrhizal Arctostaphylos directly adjacent to arbuscular mycorrhizal Adenostoma. Vegetation surveys and seedling survival assays show that Pseudotsuga establishes only in Arctostaphylos. We found no significant differences between Arctostaphylos and Adenostoma in allelopathy; light; temperature; or soil NH4+, NO3-, or K. Arctostaphylos soils tended to be higher in phosphate and were lower in pH, Ca, Mg, Ni, and Cr than those from Adenostoma. After 1 year of growth of Pseudotsuga seedlings in an Arctostaphylos patch, 17 species of fungi colonized both Pseudotsuga and Arctostaphylos. Fifty-six of 66 seedlings were colonized by fungi that also colonized Arctostaphylos within the same soil core. Forty-nine percent of the Pseudotsuga ectomycorrhizal biomass was colonized by fungi that were also associated with Arctostaphylos within the same core. Another 12% was colonized by fungi known to associate with Arctostaphylos from different cores. After 4 months of growth, Pseudotsuga seedlings in four of five Arctostaphylos plots were ectomycorrhizal and colonized by fungi in Russulaceae, Thelephoraceae, and Amanitaceae. Pseudotsuga seedlings in two of five Adenostoma plots were ectomycorrhizal but colonized by only two species of fungi in Thelephoraceae. These results provide compelling evidence that ectomycorrhizal fungi associated with Arctostaphylos contribute to Pseudotsuga seedling establishment.Key words: arbutoid, Douglas-fir, ectomycorrhizae, manzanita, RFLP, PCR.

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