The Microscopy of Compatibility and Incompatibility in Ulmus

1985 ◽  
Vol 43 ◽  
pp. 504-505
Author(s):  
B. L. Redmond ◽  
Christopher F. Bob
Keyword(s):  
Dutch Elm Disease ◽  
Economic Losses ◽  
Hybrid Progeny ◽  
Ulmus Pumila ◽  
Ulmus Americana ◽  
American Elm ◽  
Asian Species ◽  
Ulmus Parvifolia ◽  
Initial Appearance ◽  
Chinese Elm

The American Elm (Ulmus americana L.) has been plagued by Dutch Elm Disease (DED), a lethal disease caused by the fungus Ceratocystis ulmi (Buisman) c. Moreau. Since its initial appearance in North America around 1930, DED has wrought inexorable devastation on the American elm population, triggering both environmental and economic losses. In response to the havoc caused by the disease, many attempts have been made to hybridize U. americana with a few ornamentally less desirable, though highly DED resistant, Asian species (mainly the Siberian elm, Ulmus pumila L., and the Chinese elm Ulmus parvifolia Jacq.). The goal is to develop, through breeding efforts, hybrid progeny that display the ornamentally desirable characteristics of U. americana with the disease resistance of the Asian species. Unfortunately, however, all attempts to hybridize U. americana have been prevented by incompatibility. Only through a firm understanding of both compatibility and incompatibility will it be possible to circumvent the incompatibility and hence achieve hybridization.

scholarly journals Evaluation of 19 American Elm Clones for Tolerance to Dutch Elm Disease

2005 ◽  
Vol 23 (1) ◽  
pp. 21-24 ◽  
Author(s):  
A. M. Townsend ◽  
S. E. Bentz ◽  
L. W. Douglass
Keyword(s):  
Block Design ◽  
Dutch Elm Disease ◽  
Stem Cuttings ◽  
Ulmus Americana ◽  
American Elm ◽  
Foliar Symptoms ◽  
Randomized Block Design ◽  
New Harmony ◽  
Crown Dieback ◽  
Valley Forge

Abstract Rooted stem cuttings of 19 American elm (Ulmus americana L.) cultivars and selections, and rooted cuttings of two non-American elm selections, U. carpinifolia Gleditsch 51 and 970 (U. glabra Huds. x (U. wallichiana Planch. x U. carpinifolia)), along with a group of American elm seedlings, were planted in a randomized block design. When the trees were nine years old, they were inoculated with a mixed spore suspension of Ophiostoma ulmi (Buisman) C. Nannf. and Ophiostoma novo-ulmi Brasier, the causal fungi for Dutch elm disease (DED). Analyses of variance showed highly significant variation among clones in foliar symptoms 4 weeks after inoculation and in crown dieback one and two years after inoculation. After two years, 13 of the American clones showed significantly less dieback than the American elm seedlings, and 18 American clones showed significantly less injury than a randomly chosen, unselected American elm clone, 57845. The American clones with the most DED-tolerance were cultivars ‘Valley Forge,’ ‘Princeton,’ ‘Delaware,’ and ‘New Harmony,’ and selections N3487, R18-2, 290, 190, and GDH. The non-American selections 51 and 970 also exhibited high levels of disease tolerance. Most susceptible were American clones 57845, ‘Augustine,’ Crandall, W590, and the American elm seedlings. The most disease-tolerant American elm selections identified in this study are being evaluated further for possible naming and release to the nursery industry.

Preliminary assessments of shoot cold tolerance for American elm bred for enhanced tolerance to Dutch elm disease

2021 ◽  
Author(s):  
Paul Schaberg ◽  
Paula Murakami ◽  
Christopher F. Hansen ◽  
Gary J. Hawley ◽  
Christian O. Marks ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Cold Tolerance ◽  
Dutch Elm Disease ◽  
Freezing Injury ◽  
Ulmus Americana ◽  
American Elm ◽  
The North ◽  
Cold Tolerant ◽  
Using Data ◽  
Plant Hardiness

Although Dutch elm disease (DED) is the primary threat to American elm (Ulmus americana L.), we hypothesized that shoot freezing injury may also limit tree productivity and survival in the north. We assessed shoot cold tolerance and field winter injury of American elm bred for DED tolerance planted in Lemington, VT. We tested for differences in cold tolerance associated with date, maternal DED tolerance source, paternal sources from plant hardiness zones 5a, 6a and 6b (determined using data from 1996-2005), and the interactions of these. Cold tolerance was greatest in the winter, followed by fall and then spring. For all dates, cold tolerance never differed between maternal DED tolerance sources. However, in mid-winter, paternal sources from zone 5a (coldest zone) were significantly more cold tolerant than sources from zone 6b (warmest zone), and sources from zone 6a were intermediate. Field freezing injury confirmed that shoots were only marginally cold tolerant relative to ambient temperature lows.

scholarly journals Variation in Response of Selected American Elm Clones to Ophiostoma ulmi

1995 ◽  
Vol 13 (3) ◽  
pp. 126-128 ◽  
Author(s):  
A.M. Townsend ◽  
S.E. Bentz ◽  
G.R. Johnson
Keyword(s):  
Dutch Elm Disease ◽  
Main Trunk ◽  
Ulmus Americana ◽  
Disease Symptoms ◽  
Ophiostoma Ulmi ◽  
American Elm ◽  
Causal Fungus ◽  
One Year ◽  
Crown Dieback ◽  
High Degree

Abstract Ramets of nine American elm (Ulmus americana L.) clones or cultivars were planted with ramets of Ulmus ‘Frontier’, Ulmus ‘Prospector’, and American elm seedlings in a randomized block, split-plot design. When they were three years old, the trees were inoculated in the main trunk on either one of two selected dates in May with a spore suspension of Ophiostoma ulmi, the causal fungus for Dutch elm disease (DED). Analyses of variance showed significant variation among clones and between inoculation dates in disease symptoms four weeks and one year after inoculation. Inoculations made on May 18 generally created significantly more symptoms than inoculations made only nine days later. Four-week symptom expression was influenced also by a significant interaction between clonal or seedling group and inoculation date. When data from both inoculation dates were combined, six American elm clones (‘American Liberty’, ‘Princeton’, 680, R18–2, 180, and 3) showed significantly fewer foliar symptoms after four weeks than the American elm seedlings and three other American elm clones. Five of these same six more tolerant American clones averaged significantly less crown dieback after one year than the other American clones or seedlings tested. One of the American elm clones (clone 3) showed a level of disease tolerance equal statistically to ‘Frontier’ and ‘Prospector’, two cultivars which have shown a high degree of tolerance to DED in other studies.

In vitro conservation of American elm (Ulmus americana): potential role of auxin metabolism in sustained plant proliferation

2012 ◽  
Vol 42 (4) ◽  
pp. 686-697 ◽  
Author(s):  
Mukund R. Shukla ◽  
A. Maxwell P. Jones ◽  
J. Alan Sullivan ◽  
Chunzhao Liu ◽  
Susan Gosling ◽  
...  
Keyword(s):  
Dutch Elm Disease ◽  
Multiplication Rate ◽  
Mature Trees ◽  
Endangered Tree ◽  
In Vitro Proliferation ◽  
Ulmus Americana ◽  
Auxin Metabolism ◽  
American Elm

An efficient procedure for the conservation of mature American elm ( Ulmus americana L.) trees that have survived the epidemics of Dutch elm disease and are potential sources of disease resistance is reported. The model utilizes in vitro proliferation of fresh and dormant buds from mature trees for cloning nearly 100 year old American elm trees. The key factors that influenced sustained growth and multiplication included optimization of culture process and auxin metabolism in the source tissue. Blocking the action of endogenous auxins through the addition of antiauxin in the proliferation medium was crucial for high multiplication rate and optimum shoot development. Addition of antiauxin also mitigated the decline in productivity observed with multiple subcultures, which will enable long-term conservation of selected germplasm. The most effective medium for long-term proliferation contained 5.0 µmol/L p-chlorophenoxyisobutyric acid with 2.2 µmol/L benzylaminopurine and 0.29 µmol/L gibberellic acid. Medium with 2.5 µmol/L indole-3-butyric acid was the best for rooting microshoots (89%). Rooted plantlets were readily acclimatized to the greenhouse environment with a 90% survival rate. The strategy developed for American elm will aid in increasing multiplication of resistant clones, facilitate long-term conservation of elite genotypes, and also provide an approach to improve conservation of other endangered tree species.

Bionomics of Scolytus schevyrewi (Coleoptera: Curculionidae) in Saskatchewan and Manitoba, Canada

2020 ◽  
pp. 1-17
Author(s):  
Jonathan Veilleux ◽  
Fiona Ross ◽  
Neil J. Holliday
Keyword(s):  
Disease Management ◽  
Natural History ◽  
Dutch Elm Disease ◽  
Ulmus Pumila ◽  
Ulmus Americana ◽  
Potential Vector ◽  
Disease Management Programmes ◽  
History Of

Abstract The invasive alien Scolytus schevyrewi Semenov (Coleoptera: Curculionidae: Scolytinae) was detected in Saskatchewan and Manitoba, Canada, in 2007. Because S. schevyrewi is a potential vector of the Dutch elm disease pathogen (Ophiostomanovo-ulmi Brasier; Fungi: Ophiostomataceae), the natural history of the beetle was studied from 2009 to 2012 in the two provinces, where the disease is managed to protect Ulmus americana Linnaeus (Ulmaceae). Typically, healthy trees become infected when their xylem is contacted during feeding by spore-bearing scolytine adults that have flown from a diseased tree; adults emerging from brood galleries in diseased trees frequently carry spores. We caught flying S. schevyrewi adults from May to October; adults were weakly attracted to healthy Ulmus Linnaeus but were strongly attracted to Ulmus pumila Linnaeus stressed by girdling. Scolytus schevrewi colonised and completed development in girdled trees and trap logs of U. pumila. In contrast to other studies, U. americana – the major source of pathogen spores in the area – was never colonised as a brood host. Our results suggest that S. schevyrewi will primarily use U. pumila, which, in Manitoba and Saskatchewan, seldom exhibits symptoms of Dutch elm disease. Thus, arrival of S. schevyrewi does not appear to require changes to Dutch elm disease management programmes.

scholarly journals Rapid Removal of Symptomatic Trees Reduces Dutch Elm Disease Infection Rates

2012 ◽  
Vol 38 (3) ◽  
pp. 99-104
Author(s):  
J. Veilleux ◽  
J. Leferink ◽  
N.J. Holliday
Keyword(s):  
Dutch Elm Disease ◽  
Infection Rates ◽  
Ulmus Americana ◽  
American Elm ◽  
Annual Prevalence ◽  
Urban Study ◽  
Rapid Removal

In the province of Manitoba, Canada, 14 communities were paired on the basis of size and location. From 2004 to 2010 in one member of each pair, rapid removal of American elm (Ulmus americana) trees that displayed symptoms of Dutch elm disease was practiced: newly symptomatic trees were removed within six weeks of symptom detection. The remaining member of each pair continued with autumn or winter removal of symptomatic trees. Treed urban study areas were selected in each community, and in 2008 an inventory of U. americana was taken in these areas. From this inventory and from records of tree removals, estimates of the number of living U. americana and prevalence of Dutch elm disease were made for each year from 2004 to 2010. Following the switch to rapid removal, the annual prevalence of Dutch elm disease in rapid removal communities was 1.5 ± 0.2%, significantly lower than in communities with autumn/winter removal (3.1 ± 0.4%). The study authors estimate that in similar areas the value of the elm resource after 10 years would be almost CAD $600,000/km2 greater if rapid removal rather than autumn/winter removal were practiced. Therefore, under conditions similar to those in these communities, rapid removal should be a component of management programs for Dutch elm disease.

scholarly journals Variation among American Elm Clones in Long-term Dieback, Growth, and Survival following Ophiostoma Inoculation

2001 ◽  
Vol 19 (2) ◽  
pp. 100-103 ◽  
Author(s):  
A.M. Townsend ◽  
L.W. Douglass
Keyword(s):  
Height Growth ◽  
Dutch Elm Disease ◽  
Stem Cuttings ◽  
Ulmus Americana ◽  
Growth And Survival ◽  
American Elm ◽  
New Harmony ◽  
Crown Dieback ◽  
Valley Forge

Abstract Rooted stem cuttings of eight American elm (Ulmus americana L.) cultivars or selections, in addition to rooted stem cuttings of two non-American elm cultivars, ‘Prospector’ (U. wilsoniana Schneid.) and ‘Frontier’ (U. carpinifolia Gleditsch x U. parvifolia Jacq.), all planted in a randomized block, split-plot design, were inoculated on either one of two dates in May 1992 with a mixed spore suspension of Ophiostoma ulmi (Buisman) C. Nannf. and Ophiostoma novo-ulmi Brasier, the causal fungi for Dutch elm disease (DED). Crown dieback and survival were recorded once yearly for 7 years following inoculations, and height growth was measured after the sixth growing season. Analyses of variance and regression showed significant differences in disease severity among all clones tested. Among the American elms, crown dieback and mortality over time were least for ‘Valley Forge,’ ‘Princeton,’ and ‘New Harmony; ’ intermediate for ‘Delaware’ and selection R18-2; and greatest for selections 57845 and 11 and the cultivar American Liberty. Dieback and survival of ‘Prospector’ and ‘Frontier,’ the non-American elms, were comparable to that of the more disease-tolerant American elm clones. Height growth on surviving American elms for six years after inoculation was greatest for ‘Valley Forge’ and ‘Princeton’ and least for 57845, 11, and ‘American Liberty.’ Results demonstrate the ability of certain American elm cultivars and selections to respond and then recover from heavy doses of the two fungi which cause DED.

Ultrastructural cell wall modifications in secondary xylem of American elm surviving the acute stage of Dutch elm disease: fibres

1981 ◽  
Vol 59 (12) ◽  
pp. 2425-2438 ◽  
Author(s):  
G. B. Ouellette
Keyword(s):  
Cell Wall ◽  
Tension Wood ◽  
Secondary Xylem ◽  
Acute Stage ◽  
Dutch Elm Disease ◽  
Tubular Structures ◽  
Ulmus Americana ◽  
American Elm ◽  
Innermost Layer ◽  
Host Parasite

Various ultrastructural cell wall modifications of fibres have been observed in artificially or naturally infected American elm (Ulmus americana L.) trees surviving the acute stage of the Dutch elm disease caused by Ceratocystis ulmi (Buism.) C. Moreau. Bands of fibres with gelatinous (SG) layers characteristic of tension wood are frequent in or near invaded tissues; similar layers are also present sometimes in cells identifiable as parenchyma. The SG layer is often different from that observed in healthy trees. Masses or bands of dense material are present which often extend perpendicular as tubular structures to the plasmalemma location. Also, orientation of fibrils in such layers may be disordinate. One or more additional lignified-like layers alternating with additional SG-like or other opaque layers may occur inside the first SG layer. The innermost layer in these cases is often lamellate.Small intracellular locules delimited by one or two wall layers also occur in other cells.The possible significance of these observations in host–parasite relationships of the disease is briefly discussed.

STUDIES ON THE INFECTION PROCESS OF CERATOCYSTIS ULMI (BUISM.) C. MOREAU IN AMERICAN ELM TREES

1962 ◽  
Vol 40 (12) ◽  
pp. 1567-1575 ◽  
Author(s):  
G. B. Ouellette
Keyword(s):  
Seasonal Changes ◽  
Cell Walls ◽  
Growth Ring ◽  
Infection Process ◽  
Dutch Elm Disease ◽  
Ulmus Americana ◽  
American Elm ◽  
Bordered Pits ◽  
Rapid Spread ◽  
Per Se

Histological studies of controlled beetle and artificially infected American elm trees (Ulmus americana L.) show that the pathogen of the Dutch elm disease, Ceratocyslis ulmi (Buism.) C. Moreau, grows extensively in all tissues of the xylem. The pathogen produces numerous small spores and hyphae, which pass from cell to cell by means of pits and direct penetration of the walls. This explains the rapid spread of the fungus in the host. Disintegration of bordered pits and of cell walls occurs as infection develops. Acute symptoms of the disease are attributed primarily to complete plugging of the vessels of small branches by the fungus and disintegration products. Gradual or partial plugging of vessels of stems and larger branches and disintegration of cell walls per se are postulated as contributing to the chronic symptoms of the disease. Crossing of the fungus from one growth ring to the next in branches is described.Host reactions to the fungus and seasonal changes in nutrients are discussed in relation to resistance. In beetle-inoculated trees, it was found that wounds extending from the crotch down the sides of the branch were the most favorable for the establishment of infection.

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