First Report of Powdery Mildew of Nandina domestica Caused by Microsphaera berberidis (Erysiphe berberidis) in the Pacific Northwest

2003 ◽  
Vol 4 (1) ◽  
pp. 30 ◽  
Author(s):  
Dean A. Glawe
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Host Species ◽  
Puget Sound ◽  
First Report ◽  
Landscape Plant ◽  
Landscape Plants ◽  
The Pacific ◽  
Microscopic Features ◽  
Plant Grown

Nandina domestica is a bamboo-like landscape plant grown widely in the Pacific Northwest. In 2000 through 2002, powdery mildew was observed on landscape plants of N. domestica in cities in the Puget Sound region. Microscopic features of the fungus present in these specimens fit those of Microsphaera berberidis, previously reported from this host species in Scotland and California. Accepted for publication 29 September 2003. Published 23 October 2003.

First Report of Powdery Mildew of Lycium chinense (Chinese Matrimony Vine) Caused by Arthrocladiella mougeotii in the Pacific Northwest

2004 ◽  
Vol 5 (1) ◽  
pp. 16
Author(s):  
Dean A. Glawe
Keyword(s):  
North America ◽  
Powdery Mildew ◽  
Medicinal Plant ◽  
Pacific Northwest ◽  
Morphological Features ◽  
Lycium Chinense ◽  
First Report ◽  
Landscape Plant ◽  
The Pacific ◽  
Plant Grown

Chinese matrimony-vine (Lycium chinense Mill.) is a traditional medicinal plant grown in China and used as a perennial landscape plant in North America. This report documents the presence of powdery mildew on L. chinense in the Pacific Northwest and describes and illustrates morphological features of the causal agent. It appears to be the first report of a powdery mildew caused by Arthrocladiella in the Pacific Northwest. Accepted for publication 10 November 2004. Published 8 December 2004.

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.

scholarly journals First Report of Powdery Mildew Caused by Leveillula taurica on Giant Blazing Star (Mentzelia laevicaulis)

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 132-132 ◽  
Author(s):  
R. K. Sampangi ◽  
D. A. Glawe ◽  
T. Barlow ◽  
S. K. Mohan
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Host Species ◽  
The United States ◽  
Similar Species ◽  
Voucher Specimen ◽  
First Report ◽  
Leveillula Taurica ◽  
The Pacific ◽  
Native Host

Mentzelia laevicaulis (Dougl. ex Hook.) Torr. & Gray (Loasaceae; common names are giant blazing star and smoothstem blazing star) is widely distributed throughout western North America in sites ranging from lowland deserts to mountainous areas in Canada and the United States. During a plant disease survey in June 2007 in the Owyhee Mountains, Canyon County, Idaho, leaves of M. laevicaulis displaying whitish, mycelial growth were collected from plants growing on stream banks and gravelly road embankments. Diseased leaves exhibited localized, chlorotic discolorations associated with signs of a powdery mildew. Of approximately 20 plants at the site, 50% were infected. White mycelia and conidia were more abundant on the adaxial leaf surfaces than on the abaxial surfaces. Severely diseased leaves were buckled and slightly twisted. By August and through September, sporulation was greatest on mature plants, and lowermost leaves were completely covered with flocculose, dense, white mycelia. Dimorphic conidia were lanceolate or cylindrical and measured (44-) 46 to 67 (-71) × (14-) 14.5 to 20 (-21) μm. DNA was extracted and PCR was used to amplify the internal transcribed spacer (ITS) region as described previously (2), except that primers ITS 5 and P3 (4) were used. The resulting 633-bp sequence (GenBank Accession No. GQ860947) included a 616-bp region identical to a sequence reported previously for Leveillula taurica (Lév.) Arnaud from eastern Washington (GenBank No. AY912077), as well as ITS regions from L. taurica previously reported from Iran (GenBank No. AB048350) (2) and Australia (GenBank No. AF 073351) (2). Based on the ITS sequence, the present fungus grouped within Khodaparast et al. (3) Clade 1 that included L. taurica strains they distinguished from other, superficially similar species of Leveillula. On the basis of morphological and sequence data, the fungus was determined to be L. taurica (1,3). A voucher specimen was deposited in the Mycology Herbarium (WSP) at Washington State University. To our knowledge, this is the first report of a named powdery mildew species from a member of the Loasaceae. The only previous report of a powdery mildew on a loasaceous host was an undetermined Oidium sp. on a species of Mentzelia (1). The discovery of L. taurica on a previously unknown native host species is further evidence that this introduced pathogen is becoming endemic to the Pacific Northwest. Native host species, such as M. laevicaulis, may play a role in the epidemiology of powdery mildew diseases caused by L. taurica on crop and ornamental species in the Pacific Northwest. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) D. A. Glawe et al. Mycol. Prog. 4:291, 2005. (3) S. A. Khodaparast et al. Mycol. Res. 105:909, 2001. (4) S. Takamatsu and Y. Kano. Mycoscience 42:135, 2001.

First Report of Powdery Mildew of Kalanchoe blossfeldiana caused by Sphaerotheca fuliginea (Podosphaera fuliginea) in the Pacific Northwest

2003 ◽  
Vol 4 (1) ◽  
pp. 39
Author(s):  
Dean A. Glawe ◽  
Rita Hummel ◽  
Grace Jack
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Sphaerotheca Fuliginea ◽  
First Report ◽  
Major Disease ◽  
The Pacific ◽  
Kalanchoe Blossfeldiana ◽  
Extension Center ◽  
Kalanchoë Blossfeldiana

Kalanchoe blossfeldiana Poelln. is a common ornamental houseplant. Although powdery mildew is a major disease of this species, there are no published reports of it in the Pacific Northwest. In August, 2002, powdery mildew was observed on six indoor K. blossfeldiana plants in an office and adjacent laboratory at the Puyallup Research and Extension Center. Accepted for publication 25 March 2003. Published 17 April 2003.

First Report of Powdery Mildew of Coreopsis Species Caused by Golovinomyces cichoracearum in the Pacific Northwest

2006 ◽  
Vol 7 (1) ◽  
pp. 57
Author(s):  
Dean A. Glawe ◽  
Gary G. Grove ◽  
Mark Nelson
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Causal Agent ◽  
Diagnostic Features ◽  
First Report ◽  
The Pacific ◽  
Powdery Mildew Disease ◽  
Golovinomyces Cichoracearum

In 2005, the authors encountered a previously unreported powdery mildew disease of Coreopsis verticillata L. (whorled tickseed) ‘Zagreb’ and C. auriculata L. (lobed tickseed) ‘Nana’ in central Washington and determined the causal agent to be Golovinomyces cichoracearum (DC.) VP Gelyuta. This report documents the occurrence of G. cichoracearum on Coreopsis species in the Pacific Northwest, and describes diagnostic features of the disease and causal agent. Accepted for publication 2 March 2006. Published 5 April 2006.

First Report of Powdery Mildew Caused by Leveillula taurica of Field-Grown Sweet Pepper in the Pacific Northwest

2010 ◽  
Vol 11 (1) ◽  
pp. 45 ◽  
Author(s):  
Dean A. Glawe ◽  
Tess Barlow ◽  
Jordan E. Eggers ◽  
Philip B. Hamm
Keyword(s):  
Powdery Mildew ◽  
Economic Impact ◽  
Pacific Northwest ◽  
Sweet Pepper ◽  
Disease Outbreak ◽  
First Report ◽  
Leveillula Taurica ◽  
The Pacific

In August 2009, a grower reported a disease affecting nearly all plants in a drip-irrigated field of sweet pepper cv. Excalibur in Umatilla Co., OR. The fungus was determined to be Leveillula taurica (Lév.) G. Arnaud, previously unreported from this host in Oregon or from field-grown peppers in the Pacific Northwest. This report documents the taxonomic determination of this species and provides information about the disease outbreak, including economic impact. Accepted for publication 18 May 2010. Published 8 July 2010.

First Report of Downy Mildew of Chives Caused by Peronospora destructor in the Pacific Northwest

2003 ◽  
Vol 4 (1) ◽  
pp. 38
Author(s):  
Dean A. Glawe
Keyword(s):  
Downy Mildew ◽  
Pacific Northwest ◽  
Puget Sound ◽  
Washington State ◽  
King County ◽  
Specialty Crops ◽  
First Report ◽  
Peronospora Destructor ◽  
The Pacific ◽  
Allium Schoenoprasum

Chive (Allium schoenoprasum L.) is one of the specialty crops grown by farmers in the Puget Sound region of Washington State. In September, 2002, downy mildew symptoms were observed in a 0.2 hectare field planting of chive near Fall City, King County, WA. Downy mildew had not been reported previously on chive in the Pacific Northwest. Accepted for publication 15 April 2003. Published 12 May 2003.

scholarly journals First Report of Powdery Mildew, Caused by an Oidium sp., on Poinsettia in California

Plant Disease ◽  
1998 ◽  
Vol 82 (1) ◽  
pp. 128-128 ◽  
Author(s):  
S. T. Koike ◽  
G. S. Saenz
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Pacific Northwest ◽  
The United States ◽  
Euphorbia Pulcherrima ◽  
American Phytopathological Society ◽  
First Report ◽  
The Pacific ◽  
Uninoculated Control ◽  
Alternative Identification

In December 1996 and January 1997, powdery mildew was observed on potted poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) plants in Monterey County, CA. Mycelia were observed on stems, petioles, mature and immature leaves, and bracts. Severely diseased leaves became twisted and bent and senesced prematurely. The white mycelia were conspicuous, epiphytic, and amphigenous; hyphae measured 4.6 to 6.9 μm in diameter. Growth initially was in patches but eventually became effused. Appressoria were slightly lobed to lobed and sometimes opposite. Conidiophore foot cells were cylindrical, sometimes bent at the base, and slightly flexuous to flexuous. Foot cells measured 30.0 to 46.2 μm × 5.8 to 6.9 μm and were followed by one to two shorter cells. Conidia were cylindrical to slightly doliform and measured 25.4 to 32.3 μm × 11.6 to 18.5 μm. The length-to-width ratios of conidia generally were greater than 2.0. Conidia were produced singly, placing the fungus in the Pseudoidium-type powdery mildew group. Conidia germinated at the ends, and no fibrosin bodies were observed. Cleistothecia were not found. The fungus was identified as an Oidium species. Pathogenicity was demonstrated by gently pressing infected leaves having abundant sporulation onto leaves of potted poinsettia plants (cvs. Freedom Red, Peter Star Marble, and Nutcracker White), incubating the plants in a moist chamber for 48 h, and then maintaining plants in a greenhouse. After 12 to 14 days, powdery mildew colonies developed on the inoculated plants, and the pathogen was morphologically identical to the original isolates. Uninoculated control plants did not develop powdery mildew. This is the first report of powdery mildew on poinsettia in California. This fungus appears similar to Microsphaera euphorbiae but has longer, slightly flexuous foot cells that do not match the description for M. euphorbiae (1,2). An alternative identification would be Erysiphe euphorbiae; however, there are no available mitosporic descriptions for morphological comparisons (1,2). In the United States, powdery mildew of poinsettia previously has been reported in various states in the Pacific Northwest, Midwest, and Northeast. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.

First Report of Powdery Mildew of Myosotis sylvatica (Wood Forget-me-not) Caused by Golovinomyces cynoglossi (Erysiphe cynoglossi) in Washington State

2004 ◽  
Vol 5 (1) ◽  
pp. 18
Author(s):  
Dean A. Glawe
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Washington State ◽  
Causal Organism ◽  
First Report ◽  
The Pacific ◽  
Western Washington ◽  
Symptoms And Signs

Wood forget-me-not cultivars are popular ornamentals in the Pacific Northwest. In western Washington, this species frequently displays symptoms and signs of powdery mildew after anthesis. This report records the disease from King, Pierce, Snohomish, and Skagit counties and describes and illustrates symptoms of the disease as well as taxonomically important features of the causal organism. Accepted for publication 29 October 2004. Published 24 November 2004.

First Report of Powdery Mildew of Hypericum perforatum (St. John's-wort) Caused by an Anamorphic Microsphaera Species in the Pacific Northwest

2004 ◽  
Vol 5 (1) ◽  
pp. 20 ◽  
Author(s):  
Dean A. Glawe
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Hypericum Perforatum ◽  
Growing Season ◽  
Morphological Features ◽  
King County ◽  
First Report ◽  
St John’S Wort ◽  
St John's Wort ◽  
The Pacific

St. John's-wort has been valued as a medicinal herb for centuries. During the 2002 growing season a specimen plant with powdery mildew symptoms was observed in a demonstration garden in Kenmore, King County, WA. This report provides information on symptoms of the disease, morphological features useful in characterizing the causal agent, and taxonomic aspects of the fungus. Accepted for publication 30 June 2004. Published 07 July 2004.

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