Infection of Douglas-fir by Leptographium wageneri

2000 ◽  
Vol 78 (10) ◽  
pp. 1254-1261 ◽  
Author(s):  
Paul F Hessburg ◽  
Everett M Hansen
Keyword(s):  
Coming Out ◽  
Phase Contrast ◽  
Fine Root ◽  
Douglas Fir ◽  
Infection Frequency ◽  
Vascular Wilt ◽  
Direct Path ◽  
Root Mortality ◽  
Lateral Root Initiation ◽  
Potting Medium

In three related experiments, root systems of 2-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were dip-inoculated with a viscous blend of Leptographium wageneri var. pseudotsugae Harrington and Cobb spores and hyphal fragments and planted in a sterile potting medium. Infection frequency and points of entry were evaluated for dormant seedlings and seedlings that had been active for 4 and 8 weeks. All putative black stain infections and other areas of sapwood discoloration were free-hand sectioned and examined with a bright-field microscope and phase-contrast optics. This technique was shown to be 100% reliable in a prior experiment with 223 inoculated Douglas-fir seedlings that paired microscope examinations with pathogen isolation. In this study, all lesions were sectioned and examined at 250-1000 diameters magnification for the presence of L. wageneri var. pseudotsugae hyphae and characteristic pathological anatomy. Complete root system dissections revealed that L. wageneri var. pseudotsugae infected roots through wounds and natural openings where a direct path to the xylem was exposed and never penetrated living cortical or cambial tissues to infect its host. Among the dormant inoculated seedlings, 63% of infections occurred through wounds associated with nursery handling. Wound infection frequency decreased to zero in seedlings inoculated 8 weeks after coming out of dormancy. Seedlings inoculated 4 and 8 weeks after coming out of dormancy were most frequently infected through openings occurring at sites of new lateral root initiation. Infection of dead fine root stubs suggested that during periods of increased fine root mortality, these sites may be important for the new infection of healthy trees and egress from already diseased trees.Key words: Black-stain root disease, Leptographium wageneri, Verticicladiella wagnerii, infection courts, wounding, vascular wilt.

Impact of tephra deposition on growth in conifers: the year of the eruption

1984 ◽  
Vol 14 (5) ◽  
pp. 731-739 ◽  
Author(s):  
Thomas M. Hinckley ◽  
Hiromi Imoto ◽  
Katharine Lee ◽  
Susan Lacker ◽  
Yasushi Morikawa ◽  
...  
Keyword(s):  
Fine Root ◽  
Height Growth ◽  
Diameter Growth ◽  
Growth Reduction ◽  
Root Mortality ◽  
Foliar Damage ◽  
Associated Species ◽  
The Impact ◽  
Total Tree ◽  
Mount St Helens

Seven sites ranging from 15 to 135 km from Mount St. Helens were selected to study the impact of air-fall tephra on the growth of Abiesamabilis (Dougl.) Forbes, A. procera Rehd., Pseudotsugamenziesii (Mirb.) Franco, Tsugaheterophylla (Raf.) Sarg., and T. mertensiana (Bong.) Carr. As tephra depth increased, there was a corresponding increase in visible foliar damage and associated decreases in diameter and height growth. Reduction in diameter growth was greater than reduction in height growth. The reduction in diameter growth approached 50% in both trees and saplings of A. amabilis. Growth reduction in true firs was greater than in associated species. This difference was related to their greater capacity for interception and retention of air-fall tephra. Damage to trees, and resulting growth reductions, were due to tephra coverage of both the foliage and the soil. Coverage of the foliage resulted in foliar damage, foliage abscission and reduction of total tree foliar area, and increased fine root mortality. Tephra coverage of the soil had the potential to restrict oxygen diffusion into the soil. However, soil oxygen concentrations less than 10% were measured only once over a 2-year period.

Root production, mortality and turnover in soil profiles as affected by clipping in a temperate grassland on the Loess Plateau

2019 ◽  
Vol 12 (6) ◽  
pp. 1059-1072
Author(s):  
Lin Wei ◽  
Pengwei Yao ◽  
Guanghua Jing ◽  
Xiefeng Ye ◽  
Jimin Cheng
Keyword(s):  
Loess Plateau ◽  
Soil Profile ◽  
Root Length ◽  
Root Biomass ◽  
Turnover Rate ◽  
Fine Root ◽  
Root Production ◽  
The Loess Plateau ◽  
Soil Layers ◽  
Root Mortality

Abstract Aims Clipping or mowing for hay, as a prevalent land-use practice, is considered to be an important component of global change. Root production and turnover in response to clipping have great implications for the plant survival strategy and grassland ecosystem carbon processes. However, our knowledge about the clipping effect on root dynamics is mainly based on root living biomass, and limited by the lack of spatial and temporal observations. The study aim was to investigate the effect of clipping on seasonal variations in root length production and mortality and their distribution patterns in different soil layers in semiarid grassland on the Loess Plateau. Methods Clipping was performed once a year in June to mimic the local spring livestock grazing beginning from 2014. The minirhizotron technique was used to monitor the root production, mortality and turnover rate at various soil depths (0–10, 10–20, 20–30 and 30–50 cm) in 2014 (from 30 May to 29 October) and 2015 (from 22 April to 25 October). Soil temperature and moisture in different soil layers were also measured during the study period. Important Findings Our results showed that: (i) Clipping significantly decreased the cumulative root production (P < 0.05) and increased the cumulative root mortality and turnover rates of the 0–50 cm soil profile for both years. (ii) Clipping induced an immediate and sharp decrease in root length production and an increase in root length mortality in all soil layers. However, with plant regrowth, root production increased and root mortality decreased gradually, with the root production at a depth of 30–50 cm even exceeding the control in September–October 2014 and April–May 2015. (iii) Clipping mainly reduced root length production and increased root length mortality in the upper 0–20 cm soil profile with rapid root turnover. However, roots at deeper soil layers were either little influenced by clipping or exhibited an opposite trend with slower turnover rate compared with the upper soil profile, leading to the downward transport of root production and living root biomass. These findings indicate that roots in deeper soil layers tend to favour higher root biomass and longer fine root life spans to maximize the water absorption efficiency under environmental stress, and also suggest that short-term clipping would reduce the amount of carbon through fine root litter into the soil, especially in the shallow soil profile.

scholarly journals Fine Root Mortality Increased by Earthquake Induced Landslides

2016 ◽  
Vol 05 (03) ◽  
pp. 172-176 ◽  
Author(s):  
Yinping Bai ◽  
Gang Yang
Keyword(s):  
Fine Root ◽  
Root Mortality

scholarly journals Distribution of Fine Roots of Ponderosa Pine and Douglas-Fir in a Central Idaho Forest

2008 ◽  
Vol 23 (4) ◽  
pp. 202-205 ◽  
Author(s):  
Gabriel Dumm ◽  
Lauren Fins ◽  
Russell T. Graham ◽  
Theresa B. Jain
Keyword(s):  
Ponderosa Pine ◽  
Root Distribution ◽  
Fine Roots ◽  
Fine Root ◽  
Douglas Fir ◽  
Tree Size ◽  
Soil Horizon ◽  
Soil Horizons ◽  
Fine Root Distribution ◽  
Root Content

Abstract This study describes soil horizon depth and fine root distribution in cores collected at two distances from the boles of Douglas-fir and ponderosa pine trees at a study site in a central Idaho forest. Concentration and content of fine roots extracted from soil cores were compared among species, soil horizons, tree size, and distance from bole. Approximately 80% of litter and humus samples contained no fine roots. The highest fine root content and concentrations of fine roots occurred in deep mineral soil for both species (1.24 g and 2.82 g/l for Douglas-fir and 0.98g and 2.24 g/l for ponderosa pine, respectively). No statistically significant differences were found in fine root content or concentration between species in any of the four soil horizons. Tree size was not a significant factor in fine root distribution in this study. Significant variables were horizon, distance from bole, and interactions among tree size, location of sample, and soil horizon. This study, which was part of a larger US Forest Service study to develop a predictive model of postfire tree mortality, provides baseline information that may be useful in predicting postfire damage to fine roots.

Whole-seedling biomass allocation, leaf area, and tissue chemistry for Douglas-fir exposed to elevated CO2 and temperature for 4 years

2003 ◽  
Vol 33 (2) ◽  
pp. 269-278 ◽  
Author(s):  
David M Olszyk ◽  
Mark G Johnson ◽  
David T Tingey ◽  
Paul T Rygiewicz ◽  
Claudia Wise ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Leaf Area ◽  
Biomass Allocation ◽  
Fine Root ◽  
Lateral Roots ◽  
Douglas Fir ◽  
Specific Leaf Mass ◽  
Leaf Mass ◽  
Seedling Biomass ◽  
Elevated Co2 And Temperature

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were grown under ambient or elevated ( ambient + 180 µmol·mol–1) CO2 and ambient or elevated (ambient + 3.5°C) temperature in outdoor, sunlit chambers with a field soil. After 4 years, seedlings were harvested and measured for leaf area, leaf, fine root (<1 mm diameter), and structural (buds, branches, stems, main root, and lateral roots >1 mm in diameter) dry masses, and leaf and fine root C/N ratio, percent sugar, and percent cellulose. Elevated CO2 did not affect biomass production or allocation for any plant organ but increased specific leaf mass, leaf C/N ratio, and percent sugar and decreased the ratio of leaf area to structural weight and leaf percent cellulose. Elevated temperature tended to reduce biomass allocation to leaves and leaf sugar concentration. Fine root percent sugar tended to increase with elevated temperature but only at elevated CO2. Therefore, for Douglas-fir seedlings growing under naturally limiting soil moisture and nutrition conditions, elevated CO2 and temperature may have little impact on biomass or leaf area except for reduced specific leaf mass with elevated CO2 and reduced biomass allocation to leaves with elevated temperature. However, both elevated CO2 and temperature may alter leaf chemistry.

scholarly journals Shifts in Ectomycorrhizal Fungal Communities and Exploration Types Relate to the Environment and Fine-Root Traits Across Interior Douglas-Fir Forests of Western Canada

2019 ◽  
Vol 10 ◽  
Author(s):  
Camille E. Defrenne ◽  
Timothy J. Philpott ◽  
Shannon H. A. Guichon ◽  
W. Jean Roach ◽  
Brian J. Pickles ◽  
...  
Keyword(s):  
Fine Root ◽  
Root Traits ◽  
Douglas Fir ◽  
Fungal Communities ◽  
Western Canada ◽  
Exploration Types

scholarly journals Changes in the risk of fine-root mortality with age: a case study in peach, Prunus persica (Rosaceae)

2002 ◽  
Vol 89 (1) ◽  
pp. 79-87 ◽  
Author(s):  
Christina E. Wells ◽  
D. Michael Glenn ◽  
David M. Eissenstat
Keyword(s):  
Prunus Persica ◽  
Fine Root ◽  
Root Mortality
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