scholarly journals First Report of Melampsora larici-populina on Populus spp. in Eastern North America

Plant Disease ◽  
2004 ◽  
Vol 88 (1) ◽  
pp. 85-85 ◽  
Author(s):  
L. Innes ◽  
L. Marchand ◽  
P. Frey ◽  
M. Bourassa ◽  
R. C. Hamelin
Keyword(s):  
North America ◽  
Ribosomal Rna ◽  
Leaf Surface ◽  
Hybrid Poplar ◽  
Western United States ◽  
Eastern North America ◽  
First Report ◽  
Melampsora Medusae ◽  
Abaxial Leaf Surface ◽  
Forest Biology

In September 2002, yellow spots were observed on the leaf surface of a hybrid poplar (Populus maximowiczii Henry × P. balsamifera L.) grown at the Berthier forest nursery (46°2′N, 73°11′W) in the St. Lawrence Valley (Lanaudière Region, Québec, Canada). Disease severity was low, but the pathogen was present on a hybrid that was previously thought to be resistant to Melampsora medusae Thuem, the only reported poplar rust in eastern North America. Uredinia typical of a Melampsora sp. were observed on the abaxial leaf surface. The observed urediniospores were longer (32 to 48 μm) than the expected range for M. medusae (23 to 35 μm) and possessed an apical bald spot; thick paraphyses were also observed. These characteristics are diagnostic of M. larici-populina Kleb (2). Samples were deposited in the National Mycological Herbarium of Canada (DAOM 232107 and 232108) and in the Quebec Forest Biology Herbarium (QFB14703 and 14704). DNA was extracted from uredinia, and the internal transcribed spacer (ITS) of the ribosomal RNA gene was amplified and sequenced (GenBank Accession Nos. AY429656 and AY429657). There was a 100% match between the two sequences obtained and that of M. larici-populina (GenBank Accession No. AY375267), but there was approximately 12% divergence with the ITS sequence of M. medusae (GenBank Accession No. AY375273-5). This is the first report of M. larici-populina in eastern North America. This fungus was reported on P. trichocarpa × P. deltoides hybrids in the western United States in the early 1990s (1). It appears that M. larici-populina can overwinter in Québec because it was observed again at the nursery in September 2003. The occurrence of M. larici-populina in eastern North America has direct implications for the poplar industry since the host specificities of M. medusae and M. larici-populina differ; P. balsamifera and P. maximowiczii are sensitive to M. larici-populina (3). Hybrids with P. balsamifera or P. trichocarpa components may be particularly at risk. References: (1) G. Newcombe and G. A. Chastagner. Plant Dis. 77:532, 1993. (2) J. Pinon. Eur. J. For. Pathol. 3:221, 1973. (3) J. Pinon. Silvae Genet. 41:25, 1992.

scholarly journals First Report of Puccinia xanthii on Sunflower in North America

Plant Disease ◽  
2002 ◽  
Vol 86 (5) ◽  
pp. 564-564 ◽  
Author(s):  
T. J. Gulya ◽  
L. D. Charlet
Keyword(s):  
South Africa ◽  
North America ◽  
Helianthus Annuus ◽  
Leaf Surface ◽  
Rust Fungi ◽  
First Report ◽  
Abaxial Leaf Surface ◽  
University Of Arizona ◽  
Plant Pathol ◽  
Size And Morphology

Puccinia xanthii Schwein., commonly known as cocklebur rust, is circumglobal on species of Xanthium and Ambrosia. This microcyclic rust has only been observed on oilseed sunflower (Helianthus annuus L.) in Australia (1) and on ornamental sunflowers in South Africa (4). In September 1999, large (4 to 10 mm), raised, chlorotic pustules were observed on the adaxial leaf surface of oilseed sunflower plants (Dekalb 3790) near Hettinger, ND. Telia were associated with the pustules on the abaxial leaf surface. No cocklebur (X. strumarium L.) plants were found in the field, but rust-infected cocklebur plants were collected several kilometers away. Approximately 10% of sunflower plants in the field were affected, and generally only one or two pustules were observed on one or two leaves per plant. In contrast, numerous leaves of cockleur plants were infected with 12 or more pustules. Teliospores from sunflower were brown, two-celled, and averaged 49 × 17 μm, with a distinctly thicker wall at the spore apex and a persistent pedicel averaging 40 μm long. Teliospores from cocklebur were morphologically similar to those from sunflower and averaged 46 × 16 μm. Size and morphology of teliospores from both hosts fit the description of P. xanthii (2). P. xanthii can be distinguished easily from the ubiquitous P. helianthi Schwein. because the latter has smaller telia (1 to 2 mm diameter) and produces wider teliospores (21 to 30 μm diameter). P. xanthii was not found in surveys of 20 other sunflower fields in southwestern North Dakota nor in 45 fields in eastern ND in 1999, nor was P. xanthii found in this or any other sunflower field in 2000 or 2001. To our knowledge, this is the first report of P. xanthii on cultivated or wild sunflower in North America. The relatively few pustules observed on oilseed sunflower agree with the observation that oilseed sunflowers are much less susceptible to P. xanthii (3) than Xanthium spp. References: (1) J. L. Alcorn and J. K. Kochman. Austral. Plant Pathol. Soc. Newsl. 5:33, 1976. (2) G. B. Cummins. Rust Fungi on Legumes and Composites in North America. University of Arizona Press, Tucson, 1978. (3) J. B. Morin et al. Can. J. Bot. 71:959, 1993. (4) Z. A. Pretorius et al. Plant Dis. 84:924, 2000.

A comparison of earthquake damage areas as a function of magnitude across the United States

1993 ◽  
Vol 83 (4) ◽  
pp. 1064-1080 ◽  
Author(s):  
G. A. Bollinger ◽  
M. C. Chapman ◽  
M. S. Sibol
Keyword(s):  
United States ◽  
North America ◽  
Ground Motion ◽  
Epicentral Distance ◽  
The United States ◽  
Western United States ◽  
Eastern North America ◽  
Similar Response ◽  
Eastern United States ◽  
The West

Abstract This study investigates the relationship between earthquake magnitude and the size of damage areas in the eastern and western United States. To quantify damage area as a function of moment magnitude (M), 149 MMI VI and VII areas for 109 earthquakes (88 in the western United States, 21 in the eastern United States and Canada) were measured. Regression of isoseismal areas versus M indicated that areas in the East were larger than those in the West, at both intensity levels, by an average 5 × in the M 4.5 to 7.5 range. In terms of radii for circles of equivalent area, these results indicate that damaging ground motion from shocks of the same magnitude extend 2 × the epicentral distance in eastern North America compared to the West. To determine source and site parameters consistent with the above results, response spectral levels for eastern North America were stochastically simulated and compared with response spectral ordinates derived from recorded strong ground motion data in the western United States. Stress-drop values of 200 bars, combined with a surficial 2-km-thick low velocity “sedimentary” layer over rock basement, produced results that are compatible with the intensity observations, i.e., similar response spectral levels in the east at approximately twice their epicentral distance in the western U.S. distance. These results suggest that ground motion modeling in eastern North America may need to incorporate source and site parameters different from those presently in general use. The results are also of importance to eastern U.S. hazard assessments as they require allowance for the larger damage areas in preparedness and mitigation programs.

First Report of Powdery Mildew of Platanus occidentalis caused by Microsphaera platani (Erysiphe platani) in Washington State

2003 ◽  
Vol 4 (1) ◽  
pp. 33 ◽  
Author(s):  
Dean A. Glawe
Keyword(s):  
North America ◽  
Powdery Mildew ◽  
Native Species ◽  
Washington State ◽  
Eastern North America ◽  
First Report ◽  
Platanus Occidentalis

American sycamore (Platanus occidentalis L.) is a common native species in eastern North America and is planted widely as a landscape tree in other regions. During a survey of powdery mildew diseases in Washington State, the fungus Microsphaera platani Howe was found on American sycamore trees in Madison Park, Seattle. This report documents the presence of M. platani in Washington State and presents information on the fungus. Accepted for publication 30 July 2003. Published 18 August 2003.

scholarly journals White Rust of Echinacea angustifolia and E. purpurea in North America Caused by a Pustula Species

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 856-856
Author(s):  
L. J. du Toit ◽  
M. L. Derie
Keyword(s):  
North America ◽  
Plant Species ◽  
Leaf Surface ◽  
Consensus Sequence ◽  
Spore Suspension ◽  
Thick Wall ◽  
Echinacea Angustifolia ◽  
White Rust ◽  
Plastic Bags ◽  
Abaxial Leaf Surface

In 2012 and 2013, foliar symptoms were observed in certified organic, 2- to 4-ha crops of Echinacea angustifolia and E. purpurea in Grant and Klickitat counties, WA. White pustules were predominant on the abaxial leaf surface, increased in number, and coalesced on E. angustifolia, with 100% infection by the end of the season; in contrast, symptoms remained sparse on E. purpurea. Symptomatic leaves of each species were collected in May 2013 in Grant Co. Sori and sporangia were typical of those of white rust on Asteraceae caused by Pustula obtusata (1), originally named Albugo tragopogonis, then P. tragopogonis (4). Hyaline sporangia (n = 50) averaged 21 ± 2 × 20 ± 2 μm (16 to 25 × 16 to 24 μm) with a 2.6 ± 0.8 μm (1.0 to 4.0 μm) thick wall. Honey-colored to dark brown oospores were embedded in the abaxial leaf surface surrounding sori on older leaves. Oospores (n = 50) averaged 75 ± 7 × 63 ± 6 μm (60 to 96 × 52 to 76 μm) and 52 ± 4 × 51 ± 4 μm (44 to 65 × 44 to 60 μm) with (including protruberances) and without the hyaline outer wall, respectively. Sori were excised and shaken in 100 ml cold (4°C), deionized water at 400 rpm for 15 min on a gyrotory shaker. DNA extracted from the resulting spore suspension was subjected to a PCR assay using oomycete specific primers (2) to amplify the cytochrome oxidase subunit II (cox2) region of mtDNA (3). The 511-nt consensus sequence of the PCR product (GenBank Accession No. KF981439) was 98% identical to a cox2 sequence of A. tragopogonis from sunflower (Helianthus annuus) (AY286221.1), and 96% identical to cox2 sequences of P. tragopogonis (GU292167.1 and GU292168.1) (= P. obtusata) (1,2,4). Pathogenicity of the white rust isolate was confirmed by inoculating 49-day-old plants of E. angustifolia and E. purpurea with a spore suspension prepared as described above. One plant/species was placed in each of six clear plastic bags in a growth chamber at 18°C with a 12-h day/12-h night cycle for 48 h. Five replicate sets of one plant/species were each inoculated with 2.2 × 105 spores/ml on the adaxial and abaxial leaf surfaces using an airbrush (8 psi). One plant/species was sprayed with water as a control treatment. The plants were resealed in the bags for 48 h. After 7 days, white pustules were observed on at least one plant species. The plants were placed in plastic bags again overnight, and re-inoculated with 2.9 × 105 spores/ml. In addition, two sunflower plants at the 4-true-leaf stage were incubated in each of two plastic bags overnight, and inoculated with the spore suspension. Two additional sunflower plants were treated with water as control plants. All plants were removed from the bags after 48 h. White rust sori with sporangia developed on all inoculated Echinacea plants within 10 days, but not on control plants of either species, nor inoculated and non-inoculated sunflower plants, verifying that the pathogen was not P. helianthicola (1,2). Since the cox2 sequence was closest to that of a sunflower white rust isolate, the pathogen appears to be closer to P. helianthicola than P. obtusata, and may be a new Pustula species. To our knowledge, this is the first documentation of white rust on E. angustifolia and E. purpurea in North America. The severity of white rust on E. angustifolia highlights the need for effective management practices. References: (1) C. Rost and M. Thines. Mycol. Progress 11:351, 2012. (2) O. Spring et al. Eur. J. Plant Pathol 131:519, 2011. (3) S. Telle and M. Thines. PloS ONE 3(10):e3584, 2008. (4) M. Thines and O. Spring. Mycotaxon 92:443, 2005.

The youngest styliolines and nowakiids (Late Devonian) currently known from New York

1986 ◽  
Vol 60 (3) ◽  
pp. 689-700 ◽  
Author(s):  
Ellis L. Yochelson ◽  
William T. Kirchgasser
Keyword(s):  
New York ◽  
North America ◽  
Wall Structure ◽  
Eastern North America ◽  
Late Devonian ◽  
Appalachian Region ◽  
The West ◽  
First Report

This is the first report of styliolines in the Angola Shale Member of the West Falls Formation in western New York. These specimens are of late Frasnian age and are the youngest individuals known from the Appalachian Region. This upward extension of range places the extinction of styliolines in eastern North America more in accord with their time of extinction in Europe. Nowakiids have also been found in the younger Hanover Shale Member, in the upper part of the Java Formation, also of late Frasnian age. These are the youngest known nowakiids from the Appalachians. Within the limits of preservation, the external characters and wall structure of the Angola styliolines are comparable with those of older specimens. The associated rare small annulated nowakiids and homotcenids have a laminated wall structure fundamentally different from that of the styliolines.

scholarly journals First Report of Powdery Mildew of Greenhouse Pepper Caused by Leveillula taurica in Canada

Plant Disease ◽  
1999 ◽  
Vol 83 (8) ◽  
pp. 781-781 ◽  
Author(s):  
R. F. Cerkauskas ◽  
J. Brown ◽  
G. Ferguson ◽  
S. Khosla
Keyword(s):  
Powdery Mildew ◽  
Leaf Surface ◽  
Morphological Characteristics ◽  
Chili Pepper ◽  
Width Ratio ◽  
Old Field ◽  
First Report ◽  
Leveillula Taurica ◽  
Plastic Bags ◽  
Abaxial Leaf Surface

In 1999, powdery mildew on cvs. Oberon and Triple 4 of greenhouse pepper (Capsicum annum L.) and cv. FireFlame of chili pepper was reported simultaneously in two commercial greenhouses at two separate locations, Leamington and Vineland, geographically separated by 290 km, in southern Ontario. Losses of 10 to 15% each in the 2 and 3.1 ha greenhouse pepper operations were noted. The greenhouse pepper industry in Canada consists of 89.4 ha with sales of $43.6 million (Canadian). Lesions appeared as a white, powdery coating on the abaxial leaf surface only, generally on the lower foliage of pepper plants, while diffuse chlorotic spots were present at corresponding locations on the adaxial surface. In chili pepper, this chlorosis was restricted to interveinal tissue, causing the leaves to have a somewhat netted appearance. In some cases, pale yellow spots appeared on the adaxial portion of the affected foliage during later stages of disease development. No cleistothecia were observed. Pyriform and cylindrical, hyaline, single-celled conidia were present in equal numbers. Both conidia had a network of crests and granules containing tiny, thornlike projections on the surface. These projections were also evident on the lower half of conidiophores. Pyriform conidia ranged in length from 61.6 to 84.0 μm (mean = 70.8, SE = 0.7) and in width from 14.0 to 25.8 μm (mean = 21.1, SE = 0.4, n = 50), with a mean length to width ratio of 3.4. Cylindrical conidia ranged in length from 54.9 to 80.1 μm (mean = 66.3, SE = 0.9) and in width from 15.7 to 24.1 μm (mean = 18.6, SE = 0.3, n = 50), with a mean length to width ratio of 3.1. Short conidial chains borne on conidiophores consisted of a pyriform conidium first followed by cylindrical conidium. Stomatal penetration and extensive endophytic mycelial growth in the mesophyll layer were evident in foliar tissue cleared with glacial acetic acid:EtOH (1:2) and stained with lactophenol cotton blue. To confirm pathogenicity, conidia from infected pepper leaves were dusted onto the water-misted abaxial leaf surface of 41-day-old greenhouse pepper cvs. Cubico and Edison, and onto the similarly treated adaxial leaf surface of 58-day-old field pepper cv. Renegade. Plants were enclosed in plastic bags for 24 h on a bench. Control plants were treated identically but not inoculated. Inoculated plants developed foliar powdery mildew symptoms, including sporulation similar to that of naturally infected plants. Occurrence of the fungus on the abaxial surface of pepper foliage, presence of endophytic mycelium, and the morphological characteristics of the imperfect state confirm the identity of the fungus. This is the first report of Leveillula taurica (Lév.) G. Arnaud on pepper in Canada. Reference: J. Palti. Bot. Rev. 54:423, 1988.

scholarly journals First Report of Powdery Mildew of Kenaf Caused by Leveillula taurica in South Africa

Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 923-923
Author(s):  
W. J. Swart ◽  
J. Terblanche
Keyword(s):  
South Africa ◽  
Powdery Mildew ◽  
Seed Quality ◽  
Leaf Surface ◽  
Hibiscus Cannabinus ◽  
First Report ◽  
Leveillula Taurica ◽  
Abaxial Leaf Surface ◽  
Extensive Growth ◽  
Northwest Province

Kenaf (Hibiscus cannabinus L.) is a fast-growing, bamboo-like annual plant belonging to the Malvaceae. The stem, which ranges from 1.5 to 4 m, presents a source of high-quality cellulose fibers. The plant is being investigated in South Africa with a view to commercial production. In April 2001, at least 50% of 4- to 5-month-old kenaf plants grown from seed in trials near Rustenburg, Northwest Province, South Africa, were observed as having powdery mildew. Signs included extensive growth of white, superficial mycelium and emergent conidiophores on the abaxial leaf surface, followed by partial defoliation. On older leaves, the abaxial leaf surface was completely covered by powdery mildew, and chlorotic and necrotic patches were clearly visible on the adaxial surface. Symptoms were observed on all five planted cultivars (Everglades 41, Cuba 108, El Salvador, SF459, and Tainung 2), and no difference in disease severity was noted among cultivars. Leveillula taurica (Lév.) Arnaud (anamorph Oidiopsis taurica [Lév.] Salmon) was subsequently identified by the presence of endophytic mycelia, often branched conidiophores, and dimorphic conidia borne singly or in short chains (1). In 100 measurements of each type, pyriform conidia averaged 69 ± 5 × 18 ± 2 μm and cylindrical conidia averaged 62 ± 6 × 16 ± 2 μm. The teleomorph was not observed. The source of L. taurica for this reported outbreak is unknown, and powdery mildew was not observed in a field of mature cotton (Gossypium hirsutum L.) growing within 10 m of the kenaf plot. L. taurica was reported on kenaf in Texas in 1992 (2) and in Italy in 1995 (3). The pathogen can cause significant losses in seed yield and reduce seed quality in susceptible kenaf cultivars. Although L. taurica has been reported from Hibiscus sabdariffa in Egypt (4), to our knowledge this is the first report of the pathogen occurring on kenaf in Africa. References: (1) H. J. Boesewinkel. Bot Rev. 46:167, 1980. (2) C. G. Cook and J. L. Riggs. Plant Dis. 79:968, 1995. (3) S. Frisullo et al. Inf. Fitopatol. 45:37–41, 1995. (4) M. Khairy, et al. Phytopathol. Medit. 10:269–271, 1971.

First Report of Powdery Mildew of Magnolia Caused by Microsphaera magnifica (Erysiphe magnifica) in the Pacific Northwest

2003 ◽  
Vol 4 (1) ◽  
pp. 37
Author(s):  
Dean A. Glawe
Keyword(s):  
United States ◽  
North America ◽  
Powdery Mildew ◽  
Pacific Northwest ◽  
Western United States ◽  
First Report ◽  
Landscape Plant ◽  
First Finding ◽  
The Pacific ◽  
First Time

Magnolia liliiflora Desrousseaux in Lamarck (orthographic variant: M. liliiflora), a species thought to have originated in China (3), is used as a landscape plant in North America. In August 2002, Microsphaera magnifica U. Braun was collected from three plants of M. liliiflora in the Magnolia collection at the Washington Park Arboretum, University of Washington, Seattle. This report documents for the first time a powdery mildew disease of a Magnolia species in the Pacific Northwest, and the first finding of M. magnifica in the western United States. Accepted for publication 14 April 2003. Published 12 May 2003.

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