scholarly journals Elm Yellows Phytoplasma Lethal to Dutch Elm Disease-Resistant Ulmus americana Cultivars

Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 560-560 ◽  
Author(s):  
W. A. Sinclair ◽  
A. M. Townsend ◽  
J. L. Sherald
Keyword(s):  
Fungal Pathogen ◽  
Methyl Salicylate ◽  
Dutch Elm Disease ◽  
Putative Hybrid ◽  
Field Plot ◽  
Ulmus Americana ◽  
New Harmony ◽  
Elm Yellows ◽  
Valley Forge ◽  
Hybrid Cultivar

Ulmus americana (American elm) clonal cultivars Independence, New Harmony, and Valley Forge, together with the triploid putative hybrid cultivar Jefferson, were tested for reaction to the elm yellows (EY) phytoplasma. These cultivars all possess resistance to the fungal pathogen Ophiostoma novo-ulmi (1,4) but had not been screened for EY resistance or tolerance. Procedures and conditions of the test were similar to those used previously for assessing EY tolerance of Eurasian elm cultivars (3). In brief, 9 to 15 saplings of each cultivar and of U. americana raised from seed (susceptible controls), growing in a field plot at Ithaca, NY, were challenged by grafting their mainstems with bark patches from U. americana naturally affected by EY. Six to nine additional trees of each clone and of the seedling group were left untreated as controls. Inoculations were performed in July 1999, and trees were evaluated for symptoms in early September 2000. Multiple individuals in every inoculated group developed the syndrome typical of EY in U. americana: epinasty, foliar yellowing, yellow discoloration and necrosis of root and stem phloem, odor of methyl salicylate from moist discolored phloem on first exposure to air, defoliation or sudden permanent wilting, and death (2). The numbers of trees with these symptoms, of those inoculated, were: 9 of 9 Independence, 7 of 11 New Harmony, 10 of 14 Valley Forge, 3 of 13 Jefferson, and 12 of 15 trees grown from seed. Untreated controls remained asymptomatic, except for one tree of Valley Forge and two trees grown from seed that became infected naturally and had symptoms like those in the grafted trees. Based on these results, the elm cultivars named above are typical of U. americana in susceptibility to, and intolerance of, EY phytoplasmal infection. Effective EY resistance or tolerance in this species, although once thought to occur in rare individuals (2), remains undocumented. References: (1) J. L. Sherald et al. Can. J. For. Res. 24:647, 1994. (2) W. A. Sinclair. 2000. Page 121 in: The Elms. C. P. Dunn, ed. Kluwer Academic Publishers, Norwell, MA. (3) W. A. Sinclair et al. Plant Dis. 84:1266–1270, 2000. (4) A. M. Townsend. 2000. Page 271 in: The Elms. C. P. Dunn, ed. Kluwer Academic Publishers, Norwell, MA.

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.

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.

scholarly journals Vegetative Propagation of American Elm (Ulmus Americana) Varieties from Softwood Cuttings

2012 ◽  
Vol 30 (2) ◽  
pp. 73-76
Author(s):  
Allison D. Oakes ◽  
Nicholas A. Kazcmar ◽  
Charles A. Maynard ◽  
William A. Powell
Keyword(s):  
Vegetative Propagation ◽  
The Other ◽  
Small Scale ◽  
Rooted Cuttings ◽  
Ulmus Americana ◽  
American Elm ◽  
Additional Testing ◽  
Control Clone ◽  
New Harmony ◽  
Valley Forge

Softwood cuttings of American elm varieties ‘Jefferson’, ‘New Harmony’, ‘Princeton’, ‘R18-2’, ‘Valley Forge’, and a tissue-cultured non-transformed control clone (BP-NT) were rooted using three different treatments to determine which method would be most suitable for small-scale propagation. The treatments included aeroponic chambers, an intermittent-mist bench in a greenhouse, and Grodan rootplugs soaked in a nutrient solution. The rootplug treatment had the highest percentage of rooted shoots (44%) followed by the intermittent-mist bench treatment (20%) and lastly by the aeroponics chambers (10%). The rooted cuttings from the rootplug treatment also looked substantially healthier and had more fresh growth four weeks after potting than the other two treatments. The Grodan rootplug treatment is recommended, but additional testing can be useful to improve the overall rooting percentage.

Studies on the Fungal Pathogen of Dutch Elm Disease

1981 ◽  
Vol 39 ◽  
pp. 400-401
Author(s):  
H.M. Mazzone ◽  
G. Wray ◽  
R. Zerillo
Keyword(s):  
Fungal Pathogen ◽  
Fungal Growth ◽  
Polymyxin B ◽  
The United States ◽  
Dutch Elm Disease ◽  
Effective Control ◽  
Sabouraud Agar ◽  
Total Inhibition ◽  
Zones Of Inhibition ◽  
Control Plate

The fungal pathogen of the Dutch elm disease (DED), Ceratocystis ulmi (Buisman) C. Moreau, has eluded effective control since its introduction in the United States more than sixty years ago. Our studies on DED include establishing biological control agents against C. ulmi. In this report we describe the inhibitory action of the antibiotic polymyxin B on the causal agent of DED.In screening a number of antibiotics against C. ulmi, we observed that filter paper discs containing 300 units (U) of polymyxin B (Difco Laboratories) per disc, produced zones of inhibition to the fungus grown on potato dextrose agar or Sabouraud agar plates (100mm x 15mm), Fig. 1a. Total inhibition of fungal growth on a plate occurred when agar overlays containing fungus and antibiotic (polymyxin B sulfate, ICN Pharmaceuticals, Inc.) were poured on the underlying agar growth medium. The agar overlays consisted of the following: 4.5 ml of 0.7% agar, 0.5 ml of fungus (control plate); 4.0 ml of 0.7% agar, 0.5 ml of fungus, 0.5 ml of polymyxin B sulfate (77,700 U). Fig. 1, b and c, compares a control plate and polymyxin plate after seven days.

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.

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