First Report of Powdery Mildew Caused by Erysiphe betae on Swiss Chard in China

Swiss chard (Beta vulgaris L. subsp. cicla) is a widely planted vegetable in China. From May to June 2013, an outbreak of powdery mildew on Swiss chard cultivar Fangzheng was observed in the commercial fields in Zhoukou city of Henan Province, located in central China. More than 80% of the plants exhibited symptoms of the disease. At the beginning of infection, circular, white, dust-like colonies of powdery mildew occurred mainly on adaxial surfaces of leaves. As the disease progressed, white mycelia covered the foliar parts of plant. No cleistothecia were found on or in collected samples. Upon microscopic evaluation, conidiophores were unbranched with the length of 63 to 126 and width of 7 to 10 μm (n = 50), produced conidia singly, and composed of a cylindrical foot cell followed by one to three short cells. Conidia were colorless, hyaline, ovoid, measured 29 to 40 × 12 to 18 μm (n = 100), lacked fibrosin bodies, and produced germ tubes on the ends of the conidia. The fungus was identified as Erysiphe betae according to the morphological features (1). To verify the identity, the internal transcribed spacer (ITS) region was amplified with the universal primers ITS1 and ITS4 (2) and sequenced. The ITS sequence obtained was assigned as Accession No. KF268348 in GenBank, which showed 100% homogeneity with two ITS sequences of E. betae isolates from UK (DQ164432 and DQ164436). Koch's postulates were conducted by inoculating 15 healthy 5-week-old plants (cv. Fangzheng) with detached infected leaves, which grew in a growth chamber under 22/16°C (day/night), 50% relative humidity, 120 μmol/m2/s light and a 16-h photoperiod. Fifteen non-inoculated plants grew in another growth chamber with the same conditions as control. Symptoms consistent with the infected field plants were observed on the inoculated plants, while no symptoms were found on the control plants. Microscopic observation revealed that the pathogen growing on the inoculated plants was consistent with the morphology of the original fungus. To our knowledge, this is the first report of E. betae infection on Swiss chard in China (3). References: (1) S. Francis. Mol. Plant Pathol. 3:119, 2002. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990. (3) R. Y. Zheng et al. Page 63 in: Flora Fungorum Sinicorum, Vol. 1, Erysiphales. Science Press, Beijing, 1987.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe heraclei on Carrot in Central China

Plant Disease ◽

10.1094/pdis-04-13-0439-pdn ◽

2014 ◽

Vol 98 (2) ◽

pp. 277-277 ◽

Cited By ~ 1

Author(s):

Y. Wang ◽

K.-D. Xu ◽

Y. Zhang ◽

K. Liu ◽

F.-L. Zhang ◽

...

Keyword(s):

Powdery Mildew ◽

Its Region ◽

The United States ◽

Henan Province ◽

Central China ◽

Control Treatment ◽

Universal Primers ◽

Post Inoculation ◽

First Report ◽

Major Region

Carrot (Daucus carota) is an important root vegetable crop in China, which accounted for 46% of global production in 2011. Carrot was grown in Henan Province on >20,000 ha/year, which ranks first in China for area of carrots harvested. In October 2012, a powdery mildew outbreak was observed in 16 investigated carrot production fields in Zhoukou, Henan Province, in central China. White colonies typical of powdery mildew were seen on leaves of affected plants. The colonies enlarged and finally coalesced. Small, scattered fruiting bodies found on the adaxial and abaxial leaf surfaces were determined microscopically to be chasmothecia. Examining the pathogen morphologically revealed that appressoria were lobed, conidiophores were straight and bore single conidia, and cylindrical foot cells were followed by one to three shorter cells in the conidiophores. Conidiophores were subhyaline and 54.1 to 66.1 × 6.1 to 8.1 μm. Conidia were barrel-cylindrical and 28.8 to 38.6 × 11.4 to 14.8 μm. Chasmothecia were subspherical, dark brown to black, formed hyphoid appendages, and 110 to 122 μm in diameter. Appendages typically had one to five branches, which were nearly dichotomous or irregular, flexuous or almost straight, and 30 to 165 μm long. Each chasmothecium contained multiple asci that were saccate, multiguttulate, short-stipitate or not, 62.5 to 63.8 × 43.2 to 45.9 μm, and each contained two to six ascospores. Ascospores were subhyaline, ovoid to ellipsoid, and 16.5 to 17.7 × 11.2 to 12.7 μm. Based on characteristics of the anamorphic and teleomorphic stages, the fungus was identified as Erysiphe heraclei (2,4). To verify the identity, the internal transcribed spacer (ITS) region of ribosomal DNA was amplified with universal primers ITS1 and ITS4, and sequenced. The ITS sequence was assigned GenBank Accession No. KC480605, and showed 100% similarity to ITS sequences of E. heraclei on carrot in GenBank (EU371725 and GU252368). Koch's postulates were completed by using detached infected leaves from 10-week-old carrot plants growing in a field to inoculate 10 healthy, 5-week-old plants of the carrot cultivar Dinghong, growing in a growth chamber under 22/16°C (day/night) cycle at 50% relative humidity with 120 μmol/m2/s light and a 14-h photoperiod. Ten non-inoculated plants served as replicates of a control treatment. Symptoms consistent with those in the field were observed on inoculated plants 20 days post-inoculation. No symptoms were observed on the control plants. Microscopic observation of the pathogen growing on the inoculated plants revealed that it was the same as the original fungus. Powdery mildew on carrot has been observed in many countries including Australia (1), Mexico (3), and the United States (2). To our knowledge, this is the first report of E. heraclei infection on carrot in central China, a major region of carrot production, although the disease has previously been observed in northwestern China (4). Further research should help to reduce losses in carrot crops caused by E. heraclei in central China. References: (1) J. H. Cunnington et al. Australas. Plant Dis. Notes 3:38, 2008. (2) D. A. Glawe et al. Plant Health Progress doi: 10.1094/PHP-2005-0114-01-HN, 2005. (3) G. Rodríguez-Alvarado et al. Plant Dis. 94:483, 2010. (4) R. Zheng and G. Chen. Pp. 97-99 in: Flora Fungorum Sinicorum Vol. 1. Erysiphales. R. Zheng et al., eds. Science Press, Beijing, 1987.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe macleayae on Macleaya microcarpa in Poland

Plant Disease ◽

10.1094/pdis-03-12-0244-pdn ◽

2012 ◽

Vol 96 (9) ◽

pp. 1376-1376 ◽

Cited By ~ 3

Author(s):

M. J. Park ◽

S. E. Cho ◽

M. Piątek ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Sequence Similarity ◽

Signs And Symptoms ◽

Its Region ◽

Botanical Garden ◽

Central China ◽

Perennial Herb ◽

Width Ratio ◽

First Report ◽

Potted Plants

Macleaya microcarpa (Maxim.) Fedde, also known as smallfruit plume poppy, is a perennial herb belonging to the family Papaveraceae. The plant, together with the better-known species M. cordata (Willd.) R. Br., is native to central China and is now planted worldwide for medicinal purposes. In October 2008 and August 2009, dozens of smallfruit plume poppy planted in the Kraków Botanical Garden, Poland, were found to be severely infected with a powdery mildew. White colonies with abundant sporulation developed on both sides of leaves and young stems, forming circular to irregular patches. Infections caused leaf yellowing and premature defoliation. The damage has been observed every year since 2009. Representative voucher specimens were deposited in the fungal herbarium of the W. Szafer Institute of Botany of the Polish Academy of Sciences (KRAM) and the Korea University herbarium (KUS). Appressoria on the mycelia were lobed, often in pairs. Conidiophores composed of three to four cells arose from the upper part of creeping hyphae, 65 to 120 × 7 to 10 μm, attenuated toward the base, sub-straight or slightly flexuous in foot-cells, and produced conidia singly. Conidia were hyaline, oblong-elliptical to doliiform, 25 to 38 × 12 to 18 μm with a length/width ratio of 1.8 to 2.6; lacked fibrosin bodies; and produced germ tubes on the subterminal position with club-shaped or lobed appressoria. The conidial surface was wrinkled to irregularly reticulate. No chasmothecia were found. The structures described above match well with the anamorph of Erysiphe macleayae R.Y. Zheng & G.Q. Chen (3). To confirm the identity of the causal fungus, the internal transcribed spacer (ITS) region of rDNA from KUS-F24459 was amplified using primers ITS5 and P3 (4) and directly sequenced. The resulting sequence of 553 bp was deposited in GenBank (Accession No. JQ681217). A GenBank BLAST search using the present data revealed >99% sequence similarity of the isolate with E. macleayae on M. cordata from Japan (AB016048). Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of three healthy potted plants. Three noninoculated plants served as controls. Plants were maintained in a greenhouse at 25°C. Inoculated plants developed signs and symptoms after 7 days, whereas the control plants remained healthy. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants. The powdery mildew infections of M. cordata associated with E. macleayae have been recorded in China and Japan (2), and more recently in Germany (1,3). To our knowledge, this is the first report of E. macleayae on M. microcarpa globally as well as in Poland. This mildew species was described in China and is endemic to Asia, where chasmothecia of the fungus were found. Only recently have powdery mildews been found on M. cordata in Germany (1,3) and now on M. microcarpa in Poland, indicating the fungus is spreading in Europe. References: (1) N. Ale-Agha et al. Schlechtendalia 17:39, 2008. (2) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , February 7, 2012. (3) A. Schmidt and M. Scholler. Mycotaxon 115:287, 2011. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe euonymi-japonici on Euonymus japonicus in Central China

Plant Disease ◽

10.1094/pdis-12-10-0942 ◽

2011 ◽

Vol 95 (5) ◽

pp. 611-611 ◽

Cited By ~ 2

Author(s):

C. W. Li ◽

Y. Zhang ◽

Y. Liu ◽

J. M. Kang ◽

X. M. Ma ◽

...

Keyword(s):

Powdery Mildew ◽

Average Length ◽

Its Region ◽

Ornamental Plant ◽

Central China ◽

Universal Primers ◽

Herbarium Specimens ◽

Individual Plant ◽

5.8S Rdna ◽

Euonymus Japonicus

Euonymus japonicus Thunb. is a popular, woody, ornamental plant in China. From June to September 2010, severe outbreaks of powdery mildew occurred on all investigated E. japonicus plants used for hedges in Zhoukou and Shangqiu cities of Henan province in central China, which is the second largest province in terms of ornamental plant cultivation. A large amount of fungicide was used to prevent the fungal disease, which caused serious environmental pollution and was estimated to result in a 40 to 60% increase in preservation cost of E. japonicus hedges. Gray-white colonies of powdery mildew fungi occurred mainly on the leaves of E. japonicus, on average approximately 50% of the leaves of an individual plant were infected by the fungi. On severely infected leaves, mycelia were amphigenous, thick, forming irregular white patches, and effused to cover the whole surface. Subsequently, these leaves became chlorotic, curled, and withered. The fungus was identified as Erysiphe euonymi-japonici (Vienn.-Bourg.) U. Braun & S. Takam on the basis of the following data of microscopic morphology with scanning electron microscopy and molecular phylogenetic analysis of the internal transcribed spacer (ITS) region. The fungus had unbranched conidiophores with an average length of 57.3 μm and width of 8.8 μm, which was composed of a cylindrical foot cell, 15 to 40 × 6 to 10 μm and one to three shorter cells or cells of about the same length. Conidia were borne singly, cylindrical, or ellipsoid-cylindrical, with an average length of 27.7 μm and width of 10.4 μm. Chasmothecia were not observed in the collected samples during the whole outbreak period. PCR amplification and sequencing of the ITS region was amplified using the universal primers ITS1 and ITS4 (4). The obtained ITS sequence was assigned Accession No. HQ012432 in GenBank, which had a 99 and 98% nt similarity with the ITS sequences (ITS region including the 5.8S rDNA) of two Erysiphe euonymi-japonici isolates from Japan and Argentina in GenBank (Accession Nos. AB250228 and AB250229 (3), respectively). To our knowledge, Erysiphe euonymi-japonici has not been reported previously from central China, although synonymous species, Oidium euonymi-japonici and Microsphaera euonymi-japonici, were reported in southwestern (Sichuan Province) (1) and eastern (Shandong Province) (2) regions. Herbarium specimens are available at the Key Laboratory of Plant Genetics and Molecular Breeding, Zhoukou Normal University, Zhoukou, China. References: (1) H. Feng. J. Sichuan For. Sci. Technol. 13:57, 1992. (2) S. Z. Li et al. J. Shandong For. Sci. Technol. 46:40, 1995. (3) S. Limkaisang et al. Mycoscience 47:327, 2006. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

Download Full-text

First Report of Nothofagus macrocarpa Dieback Caused by Phytophthora citrophthora and P. nicotianae in Chile

Plant Disease ◽

10.1094/pdis-03-11-0258 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1193-1193 ◽

Cited By ~ 2

Author(s):

A. L. Valencia ◽

R. A. Chorbadjian ◽

B. A. Latorre

Keyword(s):

Its Region ◽

Deciduous Tree ◽

Universal Primers ◽

Academic Press ◽

Central Chile ◽

First Report ◽

Phytophthora Spp ◽

Dual Cultures ◽

Root Necrosis ◽

Mycelial Suspension

The genus Nothofagus, family Nothofagaceae, comprises 36 species of trees that are native to the Southern Hemisphere. N. macrocarpa (DC.) F.M. Vásquez & R.A. Rodríguez (Roble de Santiago) is an important deciduous tree, endemic to central Chile (32 to 35°S), and found above 800 m altitude. There is an increasing interest in N. macrocarpa as an ornamental. However, a general dieback (40 to 50% prevalence) was observed at a commercial nursery in Santiago in 2009, limiting its multiplication. Symptoms are wilting, partial defoliation, reddish brown cankers on the crowns, and root necrosis. The purpose of this work was to study the etiology of the dieback in nurseries. Phytophthora was isolated from the roots and cankers of symptomatic plants (n = 3) and soil samples (using apples and avocados as baits) on amended corn meal agar (3) at 20°C for 5 days in the dark. Morphologically, P. citrophthora (Smith & Smith) Leonian, and P. nicotianae Breda de Haan were identified (2). On V8 juice agar (V8) (1), P. citrophthora formed petaloid colonies, grew between 5 and 30°C (optimum of 25°C), and produced deciduous, mono- or bipapillated sporangia of (28.1) 45.0 to 64.1 × (18.8) 32.0 to 39.2 μm. On V8, P. nicotianae produced cottony colonies, grew between 10 and 30°C (optimum of 25°C), and produced spherical, intercalary chlamydospores (mean diameter of 19.6 μm) and persistent, papillate, spherical to ovoid, ellipsoid, obpyriform sporangia of (33.2) 47.5 to 67.6 × (24.1) 30.0 to 48.9 μm. Isolates of P. citrophthora were sexually sterile, but P. nicotianae formed oogonia with amphigenous antheridia in dual cultures with P. cinnamomi (A2 compatibility type). BLAST analysis of the internal transcribed spacer (ITS) region of rDNA of isolates identified as P. citrophthora (IMI 399056 and IMI 399054, GenBank Accession Nos. JF699756 and JF699755) and P. nicotianae (IMI 399055, Accession No. JF699757), amplified by PCR using ITS universal primers (4), revealed 100% similarity with reference isolates of P. citrophthora (Accession Nos. GU259324.1 and GU259317.1) and P. nicotianae (Accession No. GU983635.1). P. citrophthora (n = 2) and P. nicotianae (n = 1) were pathogenic when wounded detached twigs (n = 5) of N. macrocarpa and N. obliqua were inoculated with 20 μl of a mycelial suspension (106 CFU/ml) of either Phytophthora spp. Twigs were placed in a moist chamber at 20°C for 12 days prior to determine the length of the necrotic lesions that developed. An equal number of noninoculated twigs were left as control. Reisolation of P. citrophthora and P. nicotianae from inoculated material was 100%. The length of the necrotic lesions (13 to 80 mm) from inoculated N. macrocarpa and N. obliqua was significantly greater (P < 0.05) compared with the controls. Regardless of Phytophthora isolates, necrotic lesions (53.9 ± 15.8 mm) in infected N. macrocarpa were significantly longer than in N. obliqua (28.6 ± 13.1 mm) (P < 0.0001). To our knowledge, this is the first report of P. citrophthora and P. nicotianae associated with dieback on N. macrocarpa in Chile. Therefore, there is a potential risk of Phytophthora dieback in N. macrocarpa in nature. References: (1) J. Ampuero et al. Plant Dis. 92:1529, 2008. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) B. A. Latorre and R. Muñoz. Plant Dis. 77:715, 1993. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

Download Full-text

First Report of Dollar Spot of Sandbur Caused by Sclerotinia homoeocarpa in Oklahoma

Plant Disease ◽

10.1094/pdis-03-14-0244-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1160-1160

Author(s):

F. Flores ◽

N. R. Walker

Keyword(s):

Warm Season ◽

Its Region ◽

Small Subunit ◽

Type I ◽

Academic Press ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

First Report ◽

Small Subunit Rdna ◽

Disturbed Soils

Sandbur (Cenchrus incertus Curtis) is a warm-season, annual, noxious, grassy weed native to southern North America. It is common in sandy, disturbed soils and can also be found in home lawns and sport fields where low turf density facilitates its establishment. In July 2013, after a period of frequent rainfall and heavy dew, symptoms of dollar spot-like lesions (1) were observed on sandbur plants growing in a mixed stand of turf-type and native warm-season grasses in Logan County, Oklahoma. Lesions, frequently associated with leaf sheaths, were tan and surrounded by a dark margin. Symptomatic leaves were surface sterilized and plated on potato dextrose agar amended with 10 ppm rifampicin, 250 ppm ampicillin, and 5 ppm fenpropathrin. After incubation, a fungus morphologically identical to Sclerotinia homoeocarpa Bennett was consistently isolated. The nuclear ribosomal internal transcribed spacer (ITS) region of two different isolates, SCL2 and SCL3, were amplified using primers ITS4 and ITS5 (2). The DNA products were sequenced and BLAST analyses were used to compare sequences with those in GenBank. The sequence for isolate SLC2 was 869 bp, contained a type I intron in the 18S small subunit rDNA, and was identical to accession EU123803. The ITS sequence for isolate SLC3 was 535 bp and identical to accession EU123802. Twenty-five-day-old seedlings of C. incertus were inoculated by placing 5-mm-diameter agar plugs, colonized by mycelia of each S. homoeocarpa isolate, onto two of the plants' leaves. Plugs were held in place with Parafilm. Two plants were inoculated with each isolate and sterile agar plugs were placed on two leaves of another seedling as control. Plants were incubated in a dew chamber at 20°C and a 12-h photoperiod. After 3 days of incubation, water-soaked lesions surrounded by a dark margin appeared on inoculated plants only. Fungi that were later identified as S. homoeocarpa isolates SLC2 and SLC3 by sequencing of the ITS region were re-isolated from symptomatic leaves, fulfilling Koch's postulates. To our knowledge, this is the first report of dollar spot on sandbur. References: (1) R. W. Smiley et al. Page 22 in: Compendium of Turfgrass Diseases. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2005. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe betae on Sugar Beet in Korea

Plant Disease ◽

10.1094/pdis-07-16-1029-pdn ◽

2017 ◽

Vol 101 (1) ◽

pp. 254-254

Author(s):

J. H. Joa ◽

K. C. Seong ◽

I. Y. Choi ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Sugar Beet ◽

First Report ◽

Erysiphe Betae

Download Full-text

First Report of Powdery Mildew on Euryops pectinatus in Italy

Plant Disease ◽

10.1094/pdis.2002.86.8.920b ◽

2002 ◽

Vol 86 (8) ◽

pp. 920-920

Author(s):

A. Garibaldi ◽

A. Minuto ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Leaf Surface ◽

Northern Italy ◽

Growth Chamber ◽

Growth Reduction ◽

First Report ◽

Similar Disease ◽

Commercial Farms ◽

White Mycelium ◽

Sphaerotheca Fusca

Euryops pectinatus is grown in Italy for landscape use in parks and gardens. In 2001, severe outbreaks of a previously unknown powdery mildew were observed in commercial farms located in Albenga (northern Italy). All green parts (leaves, stems, and petioles) became covered with a white mycelium. Infections were particularly severe on the upper leaf surface. With progress of the disease, infected leaves turned yellow and died. The presence of powdery mildew infections on leaves and stems only rarely was linked to growth reduction. Conidia were hyaline, cylindric to slightly doliform, did not show fibrosin bodies, borne in chains, and measured 24 to 41 × 12 to 20 μm. Cleistothecia were not observed. The pathogen was identified as Oidium sp. subgen. Fibroidium (1). Pathogenicity was confirmed by gently pressing diseased leaves on leaves of healthy E. pectinatus plants. Inoculated plants were maintained in a growth chamber at 20 to 24°C. After 12 to 14 days, powdery mildew symptoms developed. A similar disease of E. pectinatus was observed in 1999 in California and identified as being caused by Podosphaera (Sphaerotheca) fusca (2). It is possible that the powdery mildew observed in Italy belongs to the same species, also considering that recently the two genera, Podosphaera and Sphaerotheca, have been unified in the genus Podosphaera (1). References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (2) G. S. Saenz et al. Plant Dis. 84:1048, 2000.

Download Full-text

First Report of Anthracnose of Onion Caused by Colletotrichum coccodes in Ohio

Plant Disease ◽

10.1094/pdis-01-14-0032-pdn ◽

2014 ◽

Vol 98 (9) ◽

pp. 1271-1271 ◽

Cited By ~ 2

Author(s):

F. Baysal-Gurel ◽

N. Subedi ◽

D. P. Mamiro ◽

S. A. Miller

Keyword(s):

Leaf Tissue ◽

Its Region ◽

The United States ◽

Tween 20 ◽

Colletotrichum Coccodes ◽

Academic Press ◽

Conidial Suspension ◽

First Report ◽

Allium Cepa L ◽

Total Dna

Dry bulb onion (Allium cepa L. cvs. Pulsar, Bradley, and Livingston) plants with symptoms of anthracnose were observed in three commercial fields totaling 76.5 ha in Huron Co., Ohio, in July 2013. Symptoms were oval leaf lesions and yellowing, curling, twisting, chlorosis, and death of leaves. Nearly half of the plants in a 32.8-ha field of the cv. Pulsar were symptomatic. Concentric rings of acervuli with salmon-colored conidial masses were observed in the lesions. Conidia were straight with tapered ends and 16 to 23 × 3 to 6 μm (2). Colletotrichum coccodes (Wallr.) S. Hughes was regularly isolated from infected plants (2). Culturing diseased leaf tissue on potato dextrose agar (PDA) amended with 30 ppm rifampicin and 100 ppm ampicillin at room temperature yielded white aerial mycelia and salmon-colored conidial masses in acervuli. Numerous spherical, black microsclerotia were produced on the surface of colonies after 10 to 14 days. To confirm pathogen identity, total DNA was extracted directly from a 7-day-old culture of isolate SAM30-13 grown on PDA, using the Wizard SV Genomic DNA Purification System (Promega, Madison, WI) following the manufacturer's instructions. The ribosomal DNA internal transcribed spacer (ITS) region was amplified by PCR using the primer pair ITS1 and ITS4 (2), and sequenced. The sequence, deposited in GenBank (KF894404), was 99% identical to that of a C. coccodes isolate from Michigan (JQ682644) (1). Ten onion seedlings cv. Ebenezer White at the two- to three-leaf stage of growth were spray-inoculated with a conidial suspension (1 × 105 conidia/ml containing 0.01% Tween 20, with 10 ml applied/plant). Plants were maintained in a greenhouse (21 to 23°C) until symptoms appeared. Control plants were sprayed with sterilized water containing 0.01% Tween 20, and maintained in the same environment. After 30 days, sunken, oval lesions each with a salmon-colored center developed on the inoculated plants, and microscopic examination revealed the same pathogen morphology as the original isolates. C. coccodes was re-isolated consistently from leaf lesions. All non-inoculated control plants remained disease-free, and C. coccodes was not re-isolated from leaves of control plants. C. coccodes was reported infecting onions in the United States for the first time in Michigan in 2012 (1). This is the first report of anthracnose of onion caused by C. coccodes in Ohio. Unusually wet, warm conditions in Ohio in 2013 likely contributed to the outbreak of this disease. Timely fungicide applications will be necessary to manage this disease in affected areas. References: (1) A. K. Lees and A. J. Hilton. Plant Pathol. 52:3. 2003. (2) L. M. Rodriguez-Salamanca et al. Plant Dis. 96:769. 2012. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe diffusa, Oidium neolycopersici, and Podosphaera xanthii on Papaya in Taiwan

Plant Disease ◽

10.1094/pdis-05-11-0362 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1188-1188 ◽

Cited By ~ 6

Author(s):

J.-G. Tsay ◽

R.-S. Chen ◽

H.-L. Wang ◽

W.-L. Wang ◽

B.-C. Weng

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

Its Region ◽

Podosphaera Xanthii ◽

Oidium Neolycopersici ◽

First Report ◽

Plastic Bags ◽

The World ◽

Golovinomyces Cichoracearum ◽

Powdery Mildew Fungi

Powdery mildew can be found in most papaya (Carica papaya L.) fields during the winter and spring seasons in Taiwan. It usually causes severe yellowing of the leaf lamina and petiole and serious defoliation. Three types of powdery mildew fungi were isolated from papaya leaves in Chiayi City (23.28°N, 120.28°E) at the beginning of 2008. Conidia of the first one were single, globose, hyaline, and 24 to 36 × 14 to 18 μm (average 30.2 × 15.6 μm) without fibrosin bodies and with straight or occasionally flexuous conidiophores at the base. The second one had short pseudo-chains of two to four conidia which were ellipsoidal to ovoid, hyaline, and 24 to 40 × 12 to 16 μm (average 29.7 × 13.4 μm) without fibrosin bodies. The third type had chains of ellipsoidal conidia that were hyaline, 24 to 28 × 12 to 16 μm (average 26.3 × 14.4 μm) and contained fibrosin bodies. To confirm the identity of the three fungi, the internal transcribed spacer (ITS) region of rDNA was amplified using the primer pairs G1 (5′-TCC GTA GGT GAA CCT GCG GAA GGA T-3′)/Ed2 (5′-CGC GTA GAG CCC ACG TCG GA-3′), G1 (5′-TCC GTA GGT GAA CCT GCG GAA GGA T-3′)/On2 (5′-TGT GAT CCA TGT GAC TGG AA-3′), and S1 (5′-GGA TCA TTA CTG AGC GCG AGG CCC CG-3′)/S2 (5′-CGC CGC CCT GGC GCG AGA TAC A-3′). The alignment of obtained sequences (GenBank Accession Nos. GU358452, 507 bp; GU358451, 580 bp; and GU358450, 455 bp) showed a sequence identity of 100, 99, and 99% with the ITS sequences of Erysiphe diffusa, Oidium neolycopersici, and Podosphaera xanthii (GenBank Accession Nos. FJ378880, EU909694, and GQ927254), respectively. On the basis of morphological characteristics and ITS sequence similarities, these fungi were identified as E. diffusa (Cooke & Peck) U. Braun & S. Takam., O. neolycopersici L. Kiss, and P. xanthii (Castagne) U. Braun & S. Takam., respectively (1,3). Single colonies on papaya leaves infected with powdery mildew were identified in the laboratory and maintained on papaya leaves as inoculum. Pathogenicity was confirmed through inoculations by gently pressing a single colony of each fungus onto leaves of healthy papaya seedlings (cv. Horng-Fe). Five seedlings were inoculated for each fungus and then covered with plastic bags for 2 days. Five noninoculated seedlings served as control. After inoculation, treated plants were maintained separately from the control in different rooms of a greenhouse at 25°C under natural daylight conditions. Seven days after inoculation, typical symptoms of powdery mildew were observed on inoculated plants, but not on noninoculated plants. The same species from diseased lesions following artificial inoculation with each fungus were identified with light microscopy. Papaya was previously described as a host to O. caricae Noack in many tropical and subtropical areas of the world including Taiwan (2). However E. cruciferarum, Golovinomyces cichoracearum, Oidiopsis sicula, O. caricae, O. caricae-papayae, O. caricicola, O. indicum, O. papayae, Ovulariopsis papayae, P. caricae-papayae, P. macularis, P. xanthii, and Streptopodium caricae were reported to infect papaya (4). To our knowledge, this is the first report of papaya powdery mildew caused by E. diffusa and O. neolycopersici in the world and the first report of the three fungi found on papaya in Taiwan. References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (2) H. S. Chien and H. L. Wang. J. Agric. Res. China 33:320, 1984. (3) L. Kiss et al. Mycol. Res. 105:684, 2001. (4) J. R. Liberato et al. Mycol. Res. 108:1185, 2004.

Download Full-text

First Report of Leaf Blight Caused by Nigrospora sphaerica on Curcuma in China

Plant Disease ◽

10.1094/pdis-04-11-0284 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1190-1190

Author(s):

L. X. Zhang ◽

J. H. Song ◽

G. J. Tan ◽

S. S. Li

Keyword(s):

Disease Incidence ◽

Its Region ◽

Leaf Blight ◽

Morphological Data ◽

Future Research ◽

Leaf Margin ◽

Academic Press ◽

First Report ◽

Pathogenicity Tests ◽

Leaf Pathogen

Curcuma (family Zingiberaceae) is commonly cultivated for the use of rhizomes within traditional Chinese medicines. In October 2009 and 2010, severe leaf blight was observed on Curcuma wenyujin Y.H. Chen & C. Ling (4) in fields located in Ruian, China. The area of cultivation in Ruian encompasses 90% of the production in Zhejiang Province. Disease incidence was approximately 90% of plants observed in affected fields. Early symptoms were yellow-to-brown, irregular-shaped lesions on the leaf margin or tip. After several days, lesions expanded along the mid-vein until the entire leaf was destroyed. Blighted leaves turned grayish to dark brown and withered, and severely affected plants died. Eight fungal isolates were recovered from symptomatic C. wenyujin leaves, collected from eight different fields, on potato dextrose agar (PDA). These fungal colonies were initially white, becoming light to dark gray and produced black, spherical to subspherical, single-celled conidia (14 to 17 × 12 to 15 μm), which were borne on a hyaline vesicle at the tip of the conidiophores. On the basis of these morphological features, the isolates appeared to be similar to Nigrospora sphaerica (2). Strain ZJW-1 was selected as a representative for molecular identification. Genomic DNA was extracted from the isolate, and the internal transcribed spacer (ITS) region of the ribosomal DNA (ITS1-5.8S-ITS2) was amplified using ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) primers (3). The ITS region was further cloned and sequenced (GenBank Accession No. JF738028) and was 99% identical to N. sphaerica (GenBank Accession No. FJ478134.1). On the basis of morphological data and the ITS rDNA sequence, the isolate was determined to be N. sphaerica. Pathogenicity tests were conducted on four leaves of four C. wenyujin plants by placing agar pieces (5 mm in diameter) from 8-day-old cultures on pushpin-wounded leaves. An equal number of control plants were wounded and inoculated with noncolonized PDA agar pieces. Plants were placed in moist chambers at 25°C with a 12-h photoperiod. Brown-to-black lesions were observed on wounded leaves after 3 days and expanded to an average of 56 × 40 mm 15 days after inoculation. No symptoms developed on the control leaves. The pathogen was reisolated from the margins of necrotic tissues but not from the controls. The pathogen has been reported as a leaf pathogen on several hosts worldwide (1). To our knowledge, this is the first report of N. sphaerica as a leaf pathogen of C. wenyujin in China. Future research will focus primarily on management of this disease. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, USDA-ARS, Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , March 31, 2011. (2) E. W. Mason. Trans. Brit. Mycol. Soc. 12:152, 1927. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (4) J. Zhao et al. Molecules 15:7547, 2010.

Download Full-text