First Report of Bacterial Blight of Four O'Clock (Mirabilis jalapa), Caused by Xanthomonas campestris in California

Four o'clock (Mirabilis jalapa) is an ornamental used in California as a landscape plant. In 2000 and 2001, four o'clock transplants produced in commercial greenhouses in coastal California were severely affected by a foliar disease. Initial symptoms were small (2 to 5 mm diameter), angular, water-soaked leaf spots that often developed first on leaf edges. Spots enlarged, rapidly turned brown to dark brown, coalesced, and caused transplants to take on a blighted appearance. When leaf spots were macerated and streaked onto sucrose-peptone agar, a yellow, mucoid bacterium was consistently isolated. Based on morphological, physiological, and biochemical characteristics, we identified the bacterium as Xanthomonas campestris (2). Furthermore, Biolog GN profiles identified five Mirabilis strains as X. campestris pv. campestris with similarity values of 79.7 to 87.6%. Fatty acid analyses identified them as the same pathovar with similarity values of 75.8 to 82.1%. These strains also used cellobiose and arabinose as carbon sources and produced acid from arabinose, which are characteristic features for this pathovar. Pathogenicity was demonstrated by growing inocula of six strains in nutrient broth shake cultures for 48 h and misting 30 ml of the broth cultures (106 CFU/ml) on sets of 12 potted four o'clock plants. Control plants were misted with sterile broth. After inoculation, plants were incubated in a dew chamber (100% relative humidity at 18°C) for 24 h then maintained in a greenhouse (24 to 26°C). After 7 to 10 days, leaf spots similar to those originally observed developed on all inoculated plants. Bacteria reisolated from these plants were characterized and found to be the same as those used for inoculation. Control plants remained symptomless. Because of the biochemical similarity between Mirabilis strains and the black rot pathogen of crucifers (X. campestris pv. campestris), we inoculated sets of six cauliflower (Brassica oleracea var. botrytis cv. White Magic) plants with five Mirabilis strains and two X. campestris pv. campestris strains using the same method. After 14 days, cauliflower plants inoculated with Mirabilis strains were symptomless, while plants inoculated with the black rot pathogen developed symptoms typical of this disease. X. campestris was only reisolated from the cauliflower plants inoculated with the crucifer strains. Because the four o'clock transplants from the commercial greenhouse were produced in close proximity to vegetable hosts of other Xanthomonas pathogens, we inoculated pepper (Capsicum annuum), tomato (Lycopersicon esculentum) and four o'clock transplants with four Mirabilis strains using the method described. The four o'clock strains failed to cause any disease on pepper and tomato but resulted in typical leaf spots on four o'clock. Bacteria reisolated from four o'clock plants and characterized were the same as the original strains. All inoculation experiments were repeated and results were the same. To our knowledge, this is the first report of X. campestris on four o'clock in California and the United States. Occurrence of this disease on direct-seeded plants in enclosed greenhouses provides circumstantial evidence that the pathogen might be seedborne. This pathogen may be related to the Xanthomonas sp. reported on four o'clock in India (1). Reference: (1) J. C. Durgapal and B. M. Trivedi. Curr. Sci. 45:111, 1976 (2) N. W. Schaad et al. Laboratory Guide for Identification of Plant Pathogenic Bacteria, 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001.

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First Report of Zonate Leaf Spot Caused by Hinomyces moricola on Japanese Hop in Korea

Plant Disease ◽

10.1094/pdis-01-13-0021-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1117-1117 ◽

Cited By ~ 1

Author(s):

S. E. Cho ◽

J. H. Park ◽

S. H. Hong ◽

H. D. Shin

Keyword(s):

Its Region ◽

The United States ◽

Infected Leaf ◽

Invasive Weed ◽

Voucher Specimen ◽

First Report ◽

Leaf Spots ◽

Initial Symptoms ◽

Wide Range ◽

Humulus Japonicus

Japanese hop (Humulus japonicus Siebold & Zucc. = H. scandens (Lour.) Merr.), native to East Asia, is an annual, climbing or trailing vine. The vines can spread to cover large areas of open ground or low vegetation, eventually blanketing the land and vegetation. Pollen of H. japonicus is allergenic, and this species is considered as one of the important causes of pollinosis in Korea and China. It is a notorious invasive weed in the United States and also in France, Hungary, and Italy (1). In September 2012, zonate leaf spots were observed on Japanese hops growing in wetlands in Yeongdong County of Korea. A voucher specimen was preserved in the Korea University Herbarium (KUS-F26901). Initial symptoms included grayish-green to grayish-brown spots without border lines. As the lesions enlarged, they coalesced, leading to leaf blight. Sporophores on the leaf lesions were dominantly hypophyllous, rarely epiphyllous, solitary, erect, easily detachable, and as long as 700 μm. The upper portion of the sporophores consisted of a pyramidal head was ventricose, 320 to 520 μm long and 110 to 150 μm wide. The fungus was isolated from leaf lesions and maintained on potato dextrose agar (PDA). Sclerotia were produced on PDA after 4 to 5 weeks at 18°C without light, but conidia were not observed in culture. These morphological and cultural characteristics were consistent with those of Hinomyces moricola (I. Hino) Narumi-Saito & Y. Harada (= Cristulariella moricola (I. Hino) Redhead) (3,4). An isolate was preserved in the Korean Agricultural Culture Collection (Accession No. KACC46955). Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. The resulting sequence of 452 bp was deposited in GenBank (Accession No. KC460209). A BLAST search in GenBank revealed that the sequence showed an exact match with those of C. moricola (JQ036181 ex Acer negundo and JQ036182 ex Glycine max). To determine the pathogenicity of the fungus, according to the procedure of Cho et al. (2), sporophores with the pyramidal head were carefully detached from a lesion on the naturally infected leaf using a needle. Each sporophore was transferred individually onto five places of four detached healthy leaves. The leaves were placed in dew chambers and incubated at 16°C. Symptoms were observed after 2 days on all inoculated leaves. A number of sporophores and immature sclerotia which were morphologically identical to the ones observed in the field were formed on the abaxial surface of the leaf 2 weeks after inoculation. The pathogen was reisolated from lesions on the inoculated leaves, confirming Koch's postulates. No symptoms were observed on the control leaves kept in humid chambers for 2 weeks. H. moricola was known to cause zonate leaf spots and defoliation on a wide range of woody and annual plants (3). To the best of our knowledge, this is the first report of Hinomyces infection on Japanese hops in Korea. References: (1) Anonymous. Humulus japonicus (Cannabaceae): Japanese hop. Eur. Medit. Plant Prot. Org. (EPPO). 2012. (2) S. E. Cho et al. Plant Dis. 96:906, 2012. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, Retrieved December 8, 2012. (4) S. A. Redhead. Can. J. Bot. 53:700, 1975.

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First Report of Bacterial Leaf Spot of Spinach Caused by a Pseudomonas syringae Pathovar in California

Plant Disease ◽

10.1094/pdis.2002.86.8.921a ◽

2002 ◽

Vol 86 (8) ◽

pp. 921-921 ◽

Cited By ~ 3

Author(s):

S. T. Koike ◽

H. R. Azad ◽

D. C. Cooksey

Keyword(s):

Brassica Oleracea ◽

Beta Vulgaris ◽

Pseudomonas Syringae ◽

Leaf Spot ◽

The United States ◽

Nutrient Broth ◽

Bacterial Leaf Spot ◽

First Report ◽

Leaf Spots ◽

Initial Symptoms

In 2000 and 2001, a new disease was observed on commercial spinach (Spinacia oleracea) in the Salinas Valley, Monterey County, CA. Initial symptoms were water-soaked, irregularly shaped leaf spots (2 to 3 mm diameter). As the disease developed, spots enlarged to as much as 1 to 2 cm, were vein-delimited, and turned dark brown. Faint chlorotic halos sometimes surrounded the spots. Death of large areas of the leaf occurred if spots coalesced. Spots were visible from the adaxial and abaxial sides of leaves, and no fungal structures were observed. The disease occurred on newly expanded and mature foliage. No fungi were isolated from the spots. However, cream-colored bacterial colonies were consistently isolated on sucrose peptone agar, and these strains were nonfluorescent on King's medium B. Strains were positive for levan and negative for oxidase, arginine dihydrolase, and nitrate reductase. Strains did not grow at 36°C, did not rot potato slices, but induced a hypersensitive reaction in tobacco (Nicotiana tabacum cv. Turk). These results suggested the bacterium was similar to Pseudomonas syringae. Fatty acid methyl ester (FAME) analysis (MIS-TSBA 4.10, MIDI Inc., Newark, DE) indicated the strains were highly similar (80.1 to 89.3%) to P. syringae pv. maculicola. However, in contrast to P. syringae pv. maculicola, the spinach strains did not utilize the carbon sources erythritol, L+tartrate, L lactate, and DL-homoserine. Pathogenicity of 10 strains was tested by growing inoculum in nutrient broth shake cultures for 48 h, diluting to 106 CFU/ml, and spraying 4-week-old plants of spinach cv. Bossanova. Control plants were sprayed with sterile nutrient broth. After 5 to 8 days in a greenhouse (24 to 26°C), leaf spots identical to those observed in the field developed on cotyledons and true leaves of inoculated plants. Strains were reisolated from the spots and identified as P. syringae. Control plants remained symptomless. The 10 strains were also inoculated on beet (Beta vulgaris), Swiss chard (Beta vulgaris subsp. cicla), cilantro (Coriandrum sativum), and spinach. Spinach showed leaf spots after 8 days; however, none of the other plants developed symptoms. Two strains were inoculated onto spinach cvs. Califlay, Lion, Nordic IV, Polka, Resistoflay, Rushmore, RZ 11, Spinnaker, Springfield, Viroflay, and Whitney. Leaf spot developed on all cultivars, and the pathogen was reisolated. Because the FAME data indicated a similarity between the spinach pathogen and P. syringae pv. maculicola, we inoculated sets of spinach cv. Bolero, cabbage (Brassica oleracea subsp. capitata cv. Grenedere), and cauliflower (Brassica oleracea subsp. botrytis cv. White Rock) with three P. syringae pv. maculicola and three spinach strains. Cabbage and cauliflower developed leaf spots only when inoculated with P. syringae pv. maculicola; spinach had leaf spots only when inoculated with the spinach strains. All inoculation experiments were done twice, and the results of the two tests were the same. To our knowledge, this is the first report of bacterial leaf spot of spinach in California caused by a nonfluorescent P. syringae, and the first record of this disease in the United States. Biochemical characteristics and limited host range of the pathogen indicate the California strains are likely the same as the P. syringae pv. spinaciae pathogen that was reported in Italy (1) and Japan (2). References: (1) C. Bazzi et al. Phytopathol. Mediterr. 27:103, 1988. (2) K. Ozaki et al. Ann. Phytopathol. Soc. Jpn. 64:264, 1998.

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First Report of Bacterial Blight Caused by Pseudomonas viridiflava on Pea in Spain

Plant Disease ◽

10.1094/pdis-94-1-0128a ◽

2010 ◽

Vol 94 (1) ◽

pp. 128-128 ◽

Cited By ~ 4

Author(s):

A. Martín-Sanz ◽

J. L. Palomo ◽

M. Pérez de la Vega ◽

C. Caminero

Keyword(s):

Pseudomonas Syringae ◽

Pathogenic Bacteria ◽

Carbon Sources ◽

Preliminary Test ◽

Soft Rot ◽

First Report ◽

Leaf Spots ◽

Pea Seedlings ◽

Disease Surveys ◽

Plant Pathol

Because production of dry peas (Pisum sativum L.) is increasing in Spain, disease surveys were carried out from 2004 to 2006 in Castilla y Leon, the largest pea-producing region. In May of 2004, a leaf and stem blight caused an estimated 25% loss in yield in pea (cv. Messire) fields in El Cerrato (Palencia). Bacteria were isolated on King's B medium from 10 symptomatic plants from different fields (3). Thirty gram-negative isolates produced fluorescent, yellowish mucoid colonies. All isolates showed oxidative glucose metabolism on Hugh-Leifson medium and were levan and oxidase negative, potato soft rot positive, arginine dihydrolase negative, and tobacco hypersensitive positive. They also hydrolyzed esculine and gelatine. These results were different than those expected by Pseudomonas syringae pv. pisi and P. syringae pv. syringae (3). API 50 CH tests (bioMerieux, Marcy l'Etoile, France) revealed that all the isolates used the following carbon sources: glycerol, erythritol, l-arabinose, ribose, d-xylose, galactose, d-glucose, d-fructose, d-manose, inositol, manitol, sorbitol, d-raffinose, d-fucose, and d-arabitol. This nutritional profile is identical with that of P. viridiflava strain CFBP 6730, originally from pea plants in France. Therefore, these isolates were tentatively identified as P. viridiflava (2). Since a preliminary test demonstrated that 9 of the 30 isolates were pathogenic on pea plants, pathogenic isolates P44, P45, and P46 were selected arbitrarily for further tests. These three isolates plus strains HRI-W 1704 (P. syringae pv. pisi type race 6) and CFBP 1769 (P. syringae pv. syringae) were inoculated onto 10 pea seedlings (cv. Messire) each in two identical trials, following a described protocol (1). Seedlings inoculated with sterile distilled water were used as controls. After 10 days of incubation in a growth chamber at 22°C and 80% relative humidity, severe rotting and collapse similar to symptoms observed in fields appeared on pea seedlings inoculated with isolates P44, P45, and P46, while water-soaked leaf spots and necrotic symptoms were caused by P. syringae pv. pisi and P. pv. syringae. No symptoms were observed on plants inoculated with sterile water. Isolates recovered from symptomatic stems showed the same morphological and biochemical features of the original isolates. Sequences of 1,399 bp long from the three isolates (GenBank Accession Nos. GQ398128, GQ398129, and GQ398130) were 100% identical to P. viridiflava 16S rDNA database reference sequences. To our knowledge, this is the first report of P. viridiflava causing a disease of pea in Spain. The disease has been reported in New Zealand (4) and France (2). References: (1) E. M. Elvira-Recuenco et al. Eur. J. Plant Pathol. 109:555, 2003. (2) C. Grondeau et al. Plant Pathol. 41:495, 1992 (3) N. W. Schaad et al., eds. Laboratory Guide for the Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001. (4) J. D. Taylor et al. N. Z. J. Agric. Res. 5:432, 1972.

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First Report of Black Rot on Arugula Caused by Xanthomonas campestris pv. campestris in Argentina

Plant Disease ◽

10.1094/pdis-92-6-0980c ◽

2008 ◽

Vol 92 (6) ◽

pp. 980-980 ◽

Cited By ~ 1

Author(s):

A. M. Romero ◽

R. Zapata ◽

M. S. Montecchia

Keyword(s):

Xanthomonas Campestris ◽

Pathogenic Bacteria ◽

Biochemical Characterization ◽

Bacterial Suspension ◽

Black Rot ◽

Strictly Aerobic ◽

First Report ◽

Plastic Bags ◽

Water Plants ◽

Xanthomonas Campestris Pv Campestris

During the fall of 2005, arugula (Eruca sativa Mill.) plants grown in experimental field plots in Buenos Aires, Argentina presented V-shaped necrotic lesions on leaf margins and blackened veins with broad yellow halos, followed by leaf necrosis. At flowering, 96% of the plants were affected with 27% of the leaves with symptoms. Yellow, round, mucoid, convex, bacterial colonies were isolated from several leaves on yeast dextrose chalk agar. Two strains were further studied. Xanthomonas campestris pv. campestris Xcc8004 was used as a control. Strains were gram negative, rod shaped, strictly aerobic, catalase-positive, oxidase and urease-negative, hydrolyzed starch, gelatine and aesculin, and did not reduce nitrate (2). Pathogenicity was tested by spraying 10 3-week-old arugula plants with either a bacterial suspension (107 CFU/ml) or sterile water. Plants were placed in plastic bags for 72 h after inoculation. All inoculated plants showed necrotic lesions enlarging from the margin of the leaves 7 days after inoculation. No lesions were observed on control plants. On the basis of biochemical characterization (2) and genomic fingerprints generated by BOX-PCR (1), the pathogen was identified as X. campestris pv. campestris. To our knowledge, this is the first report of X. campestris pv. campestris causing black rot on arugula in Argentina. References: (1) J. L. Rademaker et al. Int. J. Syst. Evol. Microbiol. 50:665, 2000. (2) N. W. Schaad et al. Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001.

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First Report of Syringae Leaf Spot Caused by Pseudomonas syringae pv. syringae on Tomato in Italy

Plant Disease ◽

10.1094/pdis-91-11-1518b ◽

2007 ◽

Vol 91 (11) ◽

pp. 1518-1518 ◽

Cited By ~ 5

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. Scortichini ◽

M. L. Gullino

Keyword(s):

Pseudomonas Syringae ◽

Leaf Spot ◽

Pathogenic Bacteria ◽

Test Group ◽

The United States ◽

Nutrient Broth ◽

Tomato Plants ◽

First Report ◽

Initial Symptoms ◽

Leaf Tissues

In the spring of 2006 and 2007, grafted and nongrafted tomato plants (scion cv. Cuore di Bue, rootstock Lycopersicon lycopersicum × L. hirsutum cv. Beaufort) displaying stem and petiole necrosis were observed in many commercial greenhouses in the Piedmont of northern Italy. Initial symptoms that developed 2 to 10 days after transplanting consisted of water-soaked circular lesions (2 to 3 mm in diameter) on stems and petioles. These lesions eventually coalesced into brown-to-black areas as much as 1 cm in diameter. In some cases, necrotic areas progressed from stem petioles to leaf tissues. Thereafter, plants wilted and died within a few days. In some greenhouses, more than 80% of young plants exhibited symptoms and production was severely reduced. Two to three sections of symptomatic tissue from stems and petioles from 20 affected plants were surface disinfested in 0.5% NaOCl for 1 min and repeatedly washed in sterile deionized water. Samples were macerated in nutrient yeast dextrose broth, streaked onto nutrient yeast dextrose agar (NYDA), and incubated at 22 ± 1°C for 48 h. Light yellow colonies typical of Pseudomonas spp. were consistently isolated on NYDA. All colonies fluoresced under UV light when grown on King's B medium (3). Colonies were levan positive, oxidase negative, potato soft rot negative, arginine dihydrase negative, and tobacco hypersensitivity positive (LOPAT test; group Ia). In addition, all isolates were positive for arbutin and aesculin hydrolysis and utilized erythitol, but not adonitol, l(+)-tartrate or dl-homoserine as a carbon source. The isolates also caused severe necrotic lesions on lemon fruits and lilac leaves (4). The bacterial colonies were identified as Pseudomonas syringae pv. syringae (1). Also, repetitive-sequence PCR using the BOXA1R primer indicated that the isolates belong to pattern 4 of P. syringae pv. syringae (4). The pathogenicity of three isolates was tested twice by growing the bacterium in nutrient broth shake cultures for 48 h, pelleting the suspension, resuspending the cell pellet in sterile water to a concentration of 106 CFU/ml, and spraying 35-day-old healthy tomato plants (cv. Cuore di Bue) with the inoculum. Ten grafted and 10 nongrafted plants were inoculated, and the same number of plants was sprayed with sterile nutrient broth as a control. After inoculation, plants were covered with plastic bags for 48 h and placed in the greenhouse at 22 ± 1°C. Six days postinoculation, stem lesions, similar to those seen in the field, and leaf spots were observed on all bacteria-inoculated plants, but not on the controls. Leaf tissues did not develop symptoms. Isolations were made from the lesion margins and the resulting bacterial colonies were again identified as P. syringae pv. syringae. To our knowledge, this is the first report of Syringae leaf spot caused by P. syringae pv. syringae in Italy as well as in Europe. A bacterial spot of tomato caused by P. syringae pv. syringae has been reported in the United States (2). References: (1) A. Braun-Kiewnick and D. C. Sands. Pseudomonas. Page 84 in: Laboratory Guide for the Identification of Plant Pathogenic Bacteria. 3rd ed. N. W. Schaad et al., eds. The American Phytopathological Society, St. Paul, MN, 2001. (2) J. B. Jones et al. Phytopathology, 71:1281, 1981. (3) E. O. King et al. J. Lab. Clinic. Med. 44:301, 1954. (4) M. Scortichini et al. Plant Pathol. 52:277, 2003.

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First Report of Sclerotinia sclerotiorum on Campanula carpatica and Schizanthus × wisetonensis in Italy

Plant Disease ◽

10.1094/pdis.2002.86.1.71a ◽

2002 ◽

Vol 86 (1) ◽

pp. 71-71

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

United States ◽

Sclerotinia Sclerotiorum ◽

Ornamental Plants ◽

Soil Surface ◽

The United States ◽

First Report ◽

Potted Plants ◽

Initial Symptoms ◽

Stem Necrosis ◽

Campanula Carpatica

The production of potted ornamental plants is very important in the Albenga Region of northern Italy, where plants are grown for export to central and northern Europe. During fall 2000 and spring 2001, sudden wilt of tussock bellflower (Campanula carpatica Jacq.) and butterfly flower (Schizanthus × wisetonensis Hort.) was observed on potted plants in a commercial greenhouse. Initial symptoms included stem necrosis at the soil line and yellowing and tan discoloration of the lower leaves. As stem necrosis progressed, infected plants growing in a peat, bark compost, and clay mixture (70-20-10) wilted and died. Necrotic tissues were covered with whitish mycelia that produced dark, spherical (2 to 6 mm diameter) sclerotia. Sclerotinia sclerotiorum was consistently recovered from symptomatic stem pieces of both plants disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar amended with streptomycin sulphate at 100 ppm. Pathogenicity of three isolates obtained from each crop was confirmed by inoculating 45- to 60-day-old C. carpatica and Schizanthus × wisetonensis plants grown in containers (14 cm diameter). Inoculum that consisted of wheat kernels infested with mycelia and sclerotia of each isolate was placed on the soil surface around the base of previously artificially wounded or nonwounded plants. Noninoculated plants served as controls. All plants were maintained outdoors where temperatures ranged between 8 and 15°C. Inoculated plants developed symptoms of leaf yellowing, followed by wilt, within 7 to 10 days, while control plants remained symptomless. White mycelia and sclerotia developed on infected tissues and S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of stem blight of C. carpatica and Schizanthus × wisetonensis caused by S. sclerotiorum in Italy. The disease was previously observed on C. carpatica in Great Britain (2) and on Schizanthus sp. in the United States (1). References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (2) J. Rees. Welsh J. Agric. 1:188, 1925.

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First Report of Stigmina palmivora Causing Leaf Spots on Phoenix roebelenii in Brazil

Plant Disease ◽

10.1094/pdis-10-13-1030-pdn ◽

2014 ◽

Vol 98 (6) ◽

pp. 849-849 ◽

Cited By ~ 1

Author(s):

A. Colmán ◽

R. A. da Silva ◽

R. Alves ◽

M. Silva ◽

R. W. Barreto

Keyword(s):

Pure Culture ◽

Leaf Surface ◽

The United States ◽

Culture Collection ◽

Commonwealth Mycological Institute ◽

First Report ◽

Leaf Spots ◽

Nucleotide Homology ◽

Query Coverage ◽

Representative Samples

Phoenix roebelenii (Arecaceae), known as dwarf date (tamareira-anã in Brazil), is a palm native to Southeast Asia and widely cultivated worldwide because of its ornamental value and ease of adaptation to a broad range of climates and soil types (4). In June 2012, some individuals were observed in a private garden in the municipality of Viçosa (state of Minas Gerais, Brazil) bearing numerous necrotic lesions on its leaves. Representative samples were taken, dried in a plant press, and brought to the laboratory for examination. A fungus was regularly associated with the leaf spots. Fungal structures were mounted in lactophenol and slides were examined under a microscope (Olympus BX 51). Spores were taken from sporulating colonies with a sterile fine needle and plated on PDA for isolation. A pure culture was deposited in the culture collection of the Universidade Federal de Viçosa (accession COAD1338). A dried herbarium sample was deposited in the local herbarium (VIC39741). The fungus had the following morphology: conidiophores grouped on sporodochia, cylindrical, 12 to 29 × 5 to 6 μm, dark brown; conidiogenous cells, terminal, proliferating percurrently (annellidic), 8 to 20 × 5 to 6 μm, pale to dark brown; conidia obclavate to subcylindrical, straight, 58 to 147 × 5 to 6 μm, 6 to 16 septate, hila thickened and darkened with a thin-walled projecting papilla, dark brown, and verrucose. The morphology of the Brazilian collections agrees well with the description of Stigmina palmivora (2), a species known to cause leaf spots on P. roebelenii in the United States (Florida) and Japan (3). Pathogenicity was demonstrated through inoculation of leaves of healthy plants by placing 6 mm diameter cuture disks of COAD1338 on the leaf surface followed by incubation in a moist chamber for 48 h and then transferred to a greenhouse bench at 21 ± 3°C. Typical leaf spots were observed 15 days after inoculation. DNA was extracted from the isolate growing in pure culture and ITS and LSU sequences were generated and deposited in GenBank under the accession numbers KF656785 and KF656786, respectively. These were compared by BLASTn with other entries in GenBank, and the closest match for each region were Mycosphaerella colombiensis strain X215 and M. irregulariamosa strain CPC 1362 (EU514231, GU2114441) with 93% of nucleotide homology (over 100% query coverage) for ITS and 98% of nucleotide homology (over 100% query coverage) for LSU. There are no sequences for S. palmivora deposited in public databases for comparison, but for Stigmina platani, the type species in this genus, 86% and 96% nucleotide homology for ITS and LSU with S. palmivora were found. The genus Stigmina is regarded as being polyphyletic (1) and this is probably reflected by these low homology levels found in the BLASTn search. To our knowledge, this is the first report of Stigmina palmivora in Brazil. References: (1) P. W. Crous et al. Stud. Mycol. 75:37, 2012. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, UK, 1971. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab. ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , 2013. (4) H. Lorenzi et al. Palmeira no Brasil: Exóticas e Nativas, 2nd ed. Editora Plantarum, Nova Odessa, Brazil, 2005.

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First Occurrence of Downy Mildew of Statice, Caused by Peronospora statices, in California and the Rest of the United States

Plant Disease ◽

10.1094/pdis.1998.82.5.591a ◽

1998 ◽

Vol 82 (5) ◽

pp. 591-591 ◽

Cited By ~ 2

Author(s):

S. T. Koike ◽

P. A. Nolan ◽

S. A. Tjosvold ◽

K. L. Robb

Keyword(s):

United States ◽

Downy Mildew ◽

Fungal Growth ◽

The United States ◽

San Diego County ◽

Leaf Spots ◽

Initial Symptoms ◽

First Occurrence ◽

Humidity Chamber ◽

Favorable Conditions

In California, hybrid statice (Misty series; Limonium bellidifolium × Limonium latifolium) is grown as a commercial cutflower crop in fields and greenhouses. In 1997, downy mildew was observed on statice plantings in both southern (San Diego County) and central (Monterey and Santa Cruz counties) parts of coastal California. Initial symptoms consisted of light green, irregularly shaped leaf spots that, after a few days, became chlorotic. As disease progressed, chlorotic spots coalesced and turned necrotic, at times resulting in extensive death of leaf tissues. Under favorable conditions, the purple to gray sporulation of the pathogen could be seen on abaxial surfaces of leaves. Conidiophores had main trunks with dichotomous branches and measured 194 to 335 μm in length (mean = 229 μm) from the base to the first branches and 7 to 8 μm across at the widest part. Branch ends were slender with curved tips that measured 5 to 8 μm long. Conidia were ovoid to globose with very short pedicels, and measured 14 to 19 μm × 14 to 17 μm. Conidial surfaces appeared slightly roughened when viewed with a scanning electron microscope. Clearing leaf sections with 10% NaOH (1) revealed the presence of yellow-brown, globose oospores that measured 31 to 47 μm. The pathogen was identified as Peronospora statices (1). Pathogenicity was demonstrated by pressing leaves with abundant sporulation against healthy leaves of test plants (Misty White) and then placing inoculated plants in a humidity chamber. After 10 to 12 days, symptoms similar to those originally observed developed on inoculated plants; after 14 to 16 days, purple fungal growth morphologically similar to the original isolates grew on leaves. Uninoculated control plants did not develop symptoms or signs of downy mildew. This is the first report of downy mildew caused by P. statices on statice in California and the rest of the United States. The disease has also been confirmed on Blue Fantasia (L. bellidifolium × L. perezii). This disease has been reported previously in Italy, The Netherlands, and the United Kingdom (1). Reference: (1) G. S. Hall et al. Eur. J. Plant Pathol. 103:471, 1997.

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First Report of Alternaria Leaf Spot of Banana Caused by Alternaria alternata in the United States

Plant Disease ◽

10.1094/pdis-01-13-0007-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1116-1116 ◽

Cited By ~ 3

Author(s):

V. Parkunan ◽

S. Li ◽

E. G. Fonsah ◽

P. Ji

Keyword(s):

United States ◽

Alternaria Alternata ◽

Leaf Spot ◽

Morphological Characteristics ◽

The United States ◽

Its Sequencing ◽

Single Spore ◽

First Report ◽

Alternaria Leaf Spot ◽

Leaf Spots

Research efforts were initiated in 2003 to identify and introduce banana (Musa spp.) cultivars suitable for production in Georgia (1). Selected cultivars have been evaluated since 2009 in Tifton Banana Garden, Tifton, GA, comprising of cold hardy, short cycle, and ornamental types. In spring and summer of 2012, 7 out of 13 cultivars (African Red, Blue Torres Island, Cacambou, Chinese Cavendish, Novaria, Raja Puri, and Veinte Cohol) showed tiny, oval (0.5 to 1.0 mm long and 0.3 to 0.9 mm wide), light to dark brown spots on the adaxial surface of the leaves. Spots were more concentrated along the midrib than the rest of the leaf and occurred on all except the newly emerged leaves. Leaf spots did not expand much in size, but the numbers approximately doubled during the season. Disease incidences on the seven cultivars ranged from 10 to 63% (10% on Blue Torres Island and 63% on Novaria), with an average of 35% when a total of 52 plants were evaluated. Six cultivars including Belle, Ice Cream, Dwarf Namwah, Kandarian, Praying Hands, and Saba did not show any spots. Tissue from infected leaves of the seven cultivars were surface sterilized with 0.5% NaOCl, plated onto potato dextrose agar (PDA) media and incubated at 25°C in the dark for 5 days. The plates were then incubated at room temperature (23 ± 2°C) under a 12-hour photoperiod for 3 days. Grayish black colonies developed from all the samples, which were further identified as Alternaria spp. based on the dark, brown, obclavate to obpyriform catenulate conidia with longitudinal and transverse septa tapering to a prominent beak attached in chains on a simple and short conidiophore (2). Conidia were 23 to 73 μm long and 15 to 35 μm wide, with a beak length of 5 to 10 μm, and had 3 to 6 transverse and 0 to 5 longitudinal septa. Single spore cultures of four isolates from four different cultivars were obtained and genomic DNA was extracted and the internal transcribed spacer (ITS1-5.8S-ITS2) regions of rDNA (562 bp) were amplified and sequenced with primers ITS1 and ITS4. MegaBLAST analysis of the four sequences showed that they were 100% identical to two Alternaria alternata isolates (GQ916545 and GQ169766). ITS sequence of a representative isolate VCT1FT1 from cv. Veinte Cohol was submitted to GenBank (JX985742). Pathogenicity assay was conducted using 1-month-old banana plants (cv. Veinte Cohol) grown in pots under greenhouse conditions (25 to 27°C). Three plants were spray inoculated with the isolate VCT1FT1 (100 ml suspension per plant containing 105 spores per ml) and incubated under 100% humidity for 2 days and then kept in the greenhouse. Three plants sprayed with water were used as a control. Leaf spots identical to those observed in the field were developed in a week on the inoculated plants but not on the non-inoculated control. The fungus was reisolated from the inoculated plants and the identity was confirmed by morphological characteristics and ITS sequencing. To our knowledge, this is the first report of Alternaria leaf spot caused by A. alternata on banana in the United States. Occurrence of the disease on some banana cultivars in Georgia provides useful information to potential producers, and the cultivars that were observed to be resistant to the disease may be more suitable for production. References: (1) E. G. Fonsah et al. J. Food Distrib. Res. 37:2, 2006. (2) E. G. Simmons. Alternaria: An identification manual. CBS Fungal Biodiversity Center, Utrecht, Netherlands, 2007.

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First Report of a Leaf Spot Disease of Bells-of-Ireland (Moluccella laevis) Caused by Cercospora apii in California

Plant Disease ◽

10.1094/pdis.2003.87.2.203a ◽

2003 ◽

Vol 87 (2) ◽

pp. 203-203

Author(s):

S. T. Koike ◽

S. A. Tjosvold ◽

J. Z. Groenewald ◽

P. W. Crous

Keyword(s):

Leaf Spot ◽

Sequence Data ◽

Disease Incidence ◽

Leaf Spot Disease ◽

Conidial Suspension ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Spot Disease ◽

Leaf Spots ◽

Initial Symptoms

Bells-of-Ireland (Moluccella laevis) (Lamiaceae) is an annual plant that is field planted in coastal California (Santa Cruz County) for commercial cutflower production. In 2001, a new leaf spot disease was found in these commercially grown cutflowers. The disease was most serious in the winter-grown crops in 2001 and 2002, with a few plantings having as much as 100% disease incidence. All other plantings that were surveyed during this time had at least 50% disease. Initial symptoms consisted of gray-green leaf spots. Spots were generally oval in shape, often delimited by the major leaf veins, and later turned tan. Lesions were apparent on both adaxial and abaxial sides of the leaves. A cercosporoid fungus having fasciculate conidiophores, which formed primarily on the abaxial leaf surface, was consistently associated with the spots. Based on morphology and its host, this fungus was initially considered to be Cercospora molucellae Bremer & Petr., which was previously reported on leaves of M. laevis in Turkey (1). However, sequence data obtained from the internal transcribed spacer region (ITS1, ITS2) and the 5.8S gene (STE-U 5110, 5111; GenBank Accession Nos. AY156918 and AY156919) indicated there were no base pair differences between the bells-of-Ireland isolates from California, our own reference isolates of C. apii, as well as GenBank sequences deposited as C. apii. Based on these data, the fungus was subsequently identified as C. apii sensu lato. Pathogenicity was confirmed by spraying a conidial suspension (1.0 × 105 conidia/ml) on leaves of potted bells-of-Ireland plants, incubating the plants in a dew chamber for 24 h, and maintaining them in a greenhouse (23 to 25°C). After 2 weeks, all inoculated plants developed leaf spots that were identical to those observed in the field. C. apii was again associated with all leaf spots. Control plants, which were treated with water, did not develop any symptoms. The test was repeated and the results were similar. To our knowledge this is the first report of C. apii as a pathogen of bells-of-Ireland in California. Reference: (1) C. Chupp. A Monograph of the Fungus Genus Cercospora. Cornell University Press, Ithaca, New York, 1954.

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