Publications by W.J. Bloomberg

Effect of stand conditions on advance of Phellinus weirii in Douglas-fir plantations

Sat, 26 Aug 2000

Relationship of growth reduction in Douglas-fir to infection by Armillaria root disease in southeastern British Columbia

Sat, 26 Aug 2000

Modelling applied to analysis of crop-pest-management interactions

Sat, 26 Aug 2000

Modeling control strategies for laminated root rot in managed Douglas-fir stands: model development

Sat, 26 Aug 2000

Equipment trials for uprooting root rot-infected stumps

Sat, 26 Aug 2000

Effect of root injury and auxin treatments on adventitious root development in second-growth Douglas-fir

Sat, 26 Aug 2000

Computers in forest disease research, application and technology transfer

Sat, 26 Aug 2000

Comparison of dwarf mistletoe effects on hemlock in Alaska, British Columbia and the Pacific Northwest

Sat, 26 Aug 2000

Modelling control strategies for Phellinus weirii root rot in managed stands: model development

Sat, 26 Aug 2000

Effects of laminated root rot on relationships between stem growth and root-system size, morphology, and spatial distribution in Douglas-fir

Sat, 26 Aug 2000

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

Sat, 26 Aug 2000

Growth loss and mortality in laminated root rot infection centers in second-growth Douglas-fir on Vancouver Island

Sat, 26 Aug 2000

The epidemiology of forest nursery diseases

Sat, 26 Aug 2000

Relationship of ecosystem to Phellinus weirii root rot on southern Vancouver Island

Sat, 26 Aug 2000

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

Sat, 26 Aug 2000

A power-driven increment borer

Sat, 26 Aug 2000

A power-driven increment borer was developed from commercially available components. The power source is a 58-cc gasoline chainsaw motor which provided power sufficient to bore conifers up to 80 cm in diameter. The chain drive was converted to the rotary action needed for turning the increment borer by an Atom drilling attachment. This attachment can be adapted to all standard chainsaw motors and has forward, neutral and reverse gears. The borer was tested on over 200 western hemlock 30–60 cm dbh, over 1000 lodgepole pine with dbh up to 30 cm and a number of Douglas-fir up to 30 cm dbh. The cores were clean and easily read and the mechanical efficiency of power boring greatly exceeded that of manual operation. The unit is portable and can easily be handled by one person.

Surveying for root disease losses in British Columbia

Sat, 26 Aug 2000

Computer models as tools for forest disease management

Sat, 26 Aug 2000

A ground survey method for estimating loss caused by Phellinus weirii root rot. III. Simulation of disease spread and impact

Sat, 26 Aug 2000

A ground survey method for estimating loss caused by Phellinus weirii root rot IV. Multiple disease recording and stratification by infection intensity

Sat, 26 Aug 2000

Estimating probability of intertree root contact in second-growth Douglas-fir

Sat, 26 Aug 2000

Factors affecting transfer and spread of Phellinus weirii mycelium in roots of second-growth Douglas-fir

Sat, 26 Aug 2000

Measurement and simulation of dwarf mistletoe infection of second-growth western hemlock on southern Vancouver island

Sat, 26 Aug 2000

Disease assessment models

Sat, 26 Aug 2000

Disease caused by Fusarium in forest nurseries

Sat, 26 Aug 2000

Estimating and total extent of Phellinus weirii root rot centers using above- and below-ground disease indicators

Sat, 26 Aug 2000

A case for structured, modular, simulation models in plant pathology research

Sat, 26 Aug 2000

A ground survey method for estimating loss caused by Phellinus weirii root rot, I: Development of survey design

Sat, 26 Aug 2000

A ground survey method for estimating loss caused by Phellinus weirii root rot, II: Survey procedures and data analysis

Sat, 26 Aug 2000

A model of spread and intensification of dwarf mistletoe infection in young western hemlock stands

Sat, 26 Aug 2000

A model of damping-off and root rot of Douglas-fir seedlings caused by Fusarium oxysporum

Sat, 26 Aug 2000

Comparison of indicator variables for estimating growth reduction associated with Phellinus weirii root rot in Douglas-fir plantations

Sat, 26 Aug 2000

Total height, annual height increment, annual diameter at breast height (dbh) increment, ratio of total height to dbh, and ratio of annual height increment to annual dbh increment were assessed as indicator variables for estimating growth reduction associated with Phellinusweirii root rot of Douglas-fir (Pseudotsugamenziesii). Generally, height variables were more sensitive indicators than dbh. Total height by 2-cm-dbh classes, ratio of total height to dbh, and ratio of annual height increment to annual dbh increment were more sensitive and less variable than the other indicators. Ratio of total height to dbh was a more consistent and sensitive indicator of growth reduction than all other variables. Application of this ratio in estimating height growth reduction in three plantations indicated reductions in infected trees of 1 to 8 m over periods of 2 to 24 years, averaging 0.9 to 1.7% annually.

Model simulations of infection of Douglas-fir seedlings by Fusarium oxysporum

Sat, 26 Aug 2000

Modelling disease loss systems in forestry

Sat, 26 Aug 2000

Heatsum-emergence relationship in Douglas-fir seedlings

Sat, 26 Aug 2000

Usefulness of classifying Douglas-fir seed lots using heatsum–emergence relationship parameters was examined by (1) comparing nursery emergence with that predicted by the relationship, (2) testing seed lots for conformity to the relationship, and (3) computer simulation of emergence under various temperature regimes. The emergence parameters used were threshold heatsum (degree-hours above 0 °C that must be accumulated before emergence starts), emergence coefficient (percentage emergence per thousand degree-hours above the threshold), slow emergence percentage (percentage emergence at which the emergence rate is reduced), and slow emergence factor (amount by which the emergence coefficient is reduced). Emergence of seed lots at two nurseries was accurately predicted by a computer model based on the heatsum–emergence relationship. Five seed lots sown in growth chambers under two temperature regimes showed good conformity to the relationship. Computation of emergence percentage and days to 50 or 100% emergence was carried out by a computer model using various emergence parameter values chosen from the observed range and simulated temperature regimes comprising daily heatsums at the 0.5-cm soil depth for 40 days after sowing. These heatsums were derived by regression equation from air temperatures at a forest nursery and were increased or decreased to represent warm or cool regimes or combinations of both. Generally, emergence percentage increased and number of days to 50 or 100% emergence decreased as emergence coefficient and slow emergence percentage increased and threshold heatsum decreased. Emergence percentage was affected by temperature regime only at low emergence coefficients. Number of days to 100% emergence was affected by temperature regime only at average or high emergence coefficients.

Climatic injury in plantations and natural stands

Sat, 26 Aug 2000

Measurement of soil temperature in forest disease research

Sat, 26 Aug 2000

Problems and advances in the applications of modelling for forest insects and disease decision making in British Columbia

Thu, 20 Mar 2003

Simulation of Douglas-fir seedling root growth, damping-off and root rot

Sat, 26 Aug 2000

A mathematical system was developed to describe root growth, damping-off and root rot of Douglas-fir nursery seedlings during the first growing season. Components of the system were: i) Seedling germination, including radicle initiation, ii) Root growth, including elongation of taproot, initiation and directional elongation of first-order roots and initiation of second-order roots, iii) Pathogen behavior, including distribution, size and infectivity of Fusarium oxysporum inoculum, and iv) Infection of root tips by fungus and growth of lesions in root. Component relationships were identified as those with consistently important effects on seedlings and fungus under coastal nursery conditions. They were expressed as regressions, tabular values or probability distribution functions and were derived from published results, experiments, logical relationships and field observations.

A computer model was constructed to integrate component relationships in logical order and in a computationally tractable form. This was achieved by subdivision of the growing season into 36 5-day periods, and the use of one vertical and one horizontal plane subdivided into 2-cm intervals of depth from soil surface and distance from taproot axis. Component relationships were modified as necessary to fit the time and space divisions of the model. A maximum population of 100 seedlings could be simulated.

Reliability of the model in predicting root growth, damping-off and root disease was tested over 2 years by applying temperature regimes for the germination, shoot growth and root zones derived from correlations with weather station records. Data on F. oxysporum inoculum concentration and distribution were supplied from field results or were estimated. Average accuracy of model results was better than 90% and 80% for root growth and for root disease, respectively. Accuracy in predicting root rot mortality, tested over 2 years, averaged about 80%. The model provides choice of detail in results ranging from individual root to total population parameters.

Distribution and pathogenicity of Fusarium oxysporum in a forest nursery soil

Sat, 26 Aug 2000

A data bank system for forest tree disease and growth plots in British Columbia

Sat, 26 Aug 2000

Growth and disease measurement data over periods up to 47 years and coordinates for 22,000 trees in seven natural stands and three plantations on eastern Vancouver Island are stored on magnetic tape. A system has been developed for rapid data retrieval by using standard formatting, sequential ordering and cross-indexing of data files. A data analysis program allows choice of compilation and statistical analysis procedures to be applied to selected data subsets, including calculation of total, mean, mode, median, range, frequency distribution, and tests of conformity to normal, random or patchy distribution. Stem maps are also produced. Data subsets can consist of any logical combination of up to 37 tree growth or disease parameters. The analysis program is in modular form, allowing the addition of compilation or statistical options. Procedures for using the system are described.

Two techniques for examining root distribution

Sat, 26 Aug 2000

Importance of treatment timing in the control of fusarium root rot of Douglas-fir seedlings

Sat, 26 Aug 2000

Two soil drenches of captan aqueous suspension to Douglas-fir seedbeds, applied 20 and 40 days after sowing, significantly reduced the number of seedlings killed by root rot caused by Fusarium oxysporum, but application of the dry chemical at sowing only, or drenches at 10 and 20 days failed to reduce disease incidence. No increase in control was obtained by increasing the frequency of treatment to every 10 days for up to 40 days after sowing, or by doubling the dosage rate from 0.19 g to 0.38 g/m of row.

A computer programme for Pielou's test of randomness in spatial distribution of populations

Sat, 26 Aug 2000

A computer programme for Pielou's test of distribution of clumpiness in a population

Sat, 26 Aug 2000

Fusarium root rot of Douglas-fir seedlings

Fri, 30 May 2008

Strain differences in Fusarium oxysporum causing diseases of Douglas-fir seedlings

Fri, 23 May 2008

Diseases of Douglas-fir seedlings caused by Fusarium oxysporum

Mon, 12 May 2008

Phenology and fungus-nematode relations of corky root disease of Douglas-fir

Mon, 12 May 2008

Effect of thiram on germination of Douglas-fir seed

Thu, 03 Apr 2008

Disease of Douglas-fir seeds during cone storage

Mon, 26 Nov 2007

Chemical control of root disease of Douglas-fir seedlings in relation to fungus and nematode populations

Mon, 26 Nov 2007

A technique for recovering seeds from forest nursery beds

Thu, 08 Nov 2007

Grey mould of Douglas-fir seedlings

Thu, 25 Oct 2007

The occurrence of endophytic fungi in Douglas-fir seedlings and seeds

Thu, 25 Oct 2007

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.

The effect of chemical sterilization on the fungus population of soil in relation to root disease of Douglas-fir seedlings

Tue, 17 Feb 2004

Nursery beds were treated with methyl bromide, Mylone, Vapam, CIPC, and Simazine before sowing with Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seed. In beds treated by the first three chemicals, the incidence of seedling root disease was 15, 45, and 75% of that in the untreated bed. There was little or no reduction of disease in the Simazine- and CIPC-treated beds. Counts of fungi in soil dilution plates showed that methyl bromide and Mylone caused the greatest reduction in the total fungus population of the soil; the proportion of Trichoderma viride Pers. ex Fr. was larger and that of Penicillium spp. was smaller in soil treated by these chemicals than in soil from other treatments. Vapam caused a moderate reduction in the total population. All treatments reduced the proportion of Fusarium oxysporum Schlect. ex. Fr. in the soil, the fungus principally found to be associated with root disease; however, this proportion did not appear to be correlated with disease incidence.

Severe mineral deficiencies in Douglas-fir seedlings in a newly developed forest nursery

Tue, 17 Feb 2004

Measurement of wood moisture content using the Colman electrode

Tue, 17 Feb 2004

Colman electrodes were inserted into stem sections of Douglas-fir, western hemlock, western red cedar and black cottonwood and resistance readings were taken at wood moisture contents of 10% to 100% of maximum moisture content. In almost all the conifer sections tested, 85% or more of the readings lay within limits of ±10% moisture content about the mean curve, and over 50% were within ±5%. The variation was greater for black cottonwood. Variation was also greater in the larger than in the smaller sections. The curves for individual sections within each species had certain characteristics in common, but no two curves were identical.

Resistance readings given by Colman electrodes inserted into living black cottonwood trees showed a fairly good correlation with soil moisture content when the trees were subjected to cycles of drought and watering.

Some factors in the development of callus in popular cuttings

Wed, 11 Feb 2004

The effect of temperature, moisture content of the cutting, and location within the shoot and cutting on callus production were investigated in Populus trichocarpa Torr. and Gray, P. canadensis Moench 'Regenerata', and P. canadensis 'Robusta Bachelieri'. Callus production increased with temperature and moisture content although not to the same extent in the three varieties. Cuttings from the base of the shoot produced more callus than those from the upper part. The latter cuttings produced more callus from the end which had been lowermost in the parent shoot than that which had been uppermost. However, cuttings from the base of the shoot showed this difference between ends of cuttings only in P. 'Regenerata'.

Cytospora canker of poplars: Bark wounding in relation to canker development

Wed, 11 Feb 2004

Cuttings of Populus trichocarpa Torr. and Gray, P. × canadensis Moench 'Regenerata' and P. × canadensis ‘Robusta Bachelieri’ were adjusted to three different moisture contents, then wounded by scorching the bark. The moisture treatments differed significantly in their effects on the histological responses in tissues around the scorch wounds, the greatest contrast being in the mode of tannin deposition. Lignification was also affected by moisture content; however, fewer cells were involved in lignin changes than in tannin deposition. No suberization was observed as a result of wounding. There were qualitative and quantitative differences among the poplar varieties with respect to tannin deposition. When wounds were inoculated with Cytospora chrysosperma (Pers.) Fr., the growth of canker varied inversely as the number of tanniferous cells, the width of the tanniferous zone, and the number of lignified cells. The correlation with tannin deposition was much stronger than that with lignification. These findings suggested that the relationship previously observed between Cytospora canker growth and moisture content may operate partly through the mechanism of tannin deposition.

Use of organic residues in forest nurseries

Wed, 11 Feb 2004

A translucent rooting medium for the observation of Douglas-fir seedling roots

Wed, 11 Feb 2004

The significance of initial adventitious roots in Populus and the effect of certain factors on their development

Wed, 11 Feb 2004

In planted cuttings of Populus trichocarpa Torr. and Gray, P. x canadensis Moench 'Regenerata', and P. x canadensis 'Robusta Bachelieri', adventitious roots developed first along the cutting, then later at the basal end. Removal of the first roots, termed initial roots, resulted in decreased shoot growth during the early growth of the cuttings and a smaller root system at the end of the growing season. Mortality occurred only in those cuttings from which all initial roots had been removed. Poplar varieties differed significantly with respect to number, but not length of initial roots produced. In general, the number, length and weight of initial roots increased with the cutting moisture content and with temperature. Number of roots increased with increasing age of parent shoot up to a maximum at 10 months, with no further increase up to 16 months. Cuttings from the base of the shoot produced longer, and in the hybrids, heavier roots than cuttings from the top. At 50% moisture content, basal cuttings produced more roots than top cuttings, but at 100% moisture content, there was no significant difference between the shoot regions. The position in which cuttings were placed exerted a significant effect on the number of roots produced in the hybrids, but not in P. trichocarpa.

Cytospora canker of poplars

Wed, 13 Nov 2002

The effects of shoot moisture content, region of shoot, age of shoot, temperature, relative humidity, and soil moisture content on the development of cankers caused by Cytospora chrysosperma (Pers.) Fr. were studied in Populus trichocarpa Torr. and Gray, P. × canadensis Moench 'Regenerata', and P. × canadensis 'Robusta Bachelieri'. Within the range studied, canker growth varied proportionally with temperature, and inversely with shoot moisture content, relative humidity, and soil moisture content. Canker growth was greater in P. trichocarpa than in the two hybrids, which did not differ significantly from each other. Canker growth was less in 8-month-old than in 10- and 12-month-old shoots of the hybrids, but cankers on P. trichocarpa showed no differences in this respect. The critical bark moisture deficit for infection was least in P. trichocarpa, intermediate in P. 'Regenerata', and greatest in P. 'Robusta'. The critical bark moisture deficit was greater, and the incubation period was shorter, in the upper part than in the lower part of the shoot.

Cytospora canker of poplars

Wed, 13 Nov 2002

A comparison was made between Populus trichocarpa Torr. and Gray, P. × canadensis Moench 'Regenerata', and P. × canadensis 'Robusta Bachelieri' with respect to shoot moisture relations and anatomy. The two hybrid varieties had slower rates of moisture loss and had higher wood moisture contents throughout most of the year than P. trichocarpa. The bark and wood moisture content of the three varieties was lower during dormancy than in the growing season. The upper region of the shoots had lower bark and wood moisture contents than the basal region during dormancy, but the reverse was true in summer. In all varieties, there was a significant positive correlation between wood and bark moisture content. Compared with P. trichocarpa, the two hybrids had larger piths, wider vessels, longer phloem rays, wider sieve tube zones, and thicker periderms; P. 'Robusta' had fewer lenticels. The upper region of the shoots had a wider pith, thicker bark, thinner periderm, and more lenticels than the basal region. The differences in moisture relations and anatomy of the three varieties suggest an explanation for the observed greater resistance to canker disease caused by Cytospora chrysosperma (Pers.) Fr. in the hybrids than in P. trichocarpa.

Electrical determination of wood moisture content

Tue, 29 Oct 2002

Willow blight in British Columbia

Tue, 29 Oct 2002

Root formation of black cottonwood cuttings in relation to region of parent shoot

Tue, 29 Oct 2002

Shoots of one-year-old Populus trichocarpa Torr. and Gray were collected just after breaking of dormancy from a nursery at Lulu Island, B. C. The shoots were divided into four sections of equal length and placed in an atmosphere of 100% relative humidity at a constant temperature of 4 °C. After one month the quarters were sampled to determine the number and length of adventitious roots formed and the number of new shoots. Significant differences were found in the number and length of roots produced in different quarters of the shoot but not in the number of new shoots. There were also significant differences in root length between clones. The most numerous and longest roots occurred on the lowest quarter of the shoot and decreased acropetally. The data suggest the better performance of cuttings of P. trichocarpa from the lower portions of the shoot and the importance of vigor in individual clones.

Some physiological and anatomical characteristics of Populus spp. as related to infection by Cytospora chrysosperma Fr

Tue, 29 Oct 2002