bluuebunny/crossref_metadata_2025_split huggingface dataset:
Downy Mildew Caused by Peronospora radii on Marguerite Daisy (Argyranthemum frutescens) in California
Authors: Koike S. T. , Fogle D. , Tjosvold S. A. , King A. I. 
Published: May 2007

In California, marguerite daisy (Argyranthemum frutescens [= Chyrsanthemum frutescens]) is an important, commercially grown, perennial flowering plant that is used as a potted plant, cutflower, and landscape plant. For two seasons (2003 and 2004), a downy mildew disease has been affecting marguerite daisy at wholesale container and field cutflower nurseries and retail nurseries in coastal California (Monterey, Santa Cruz, and San Mateo counties). The disease occurred early in the season (January) and continued to infect new foliage throughout the year whenever cool, foggy weather occurred. The disease primarily affected newly expanded young leaves on shoot tips. Such leaves were chlorotic, twisted and bent, and stunted. In some cases, leaflet tips turned black and necrotic. The abaxial sides of affected leaves were heavily colonized by the extensive purplish brown growth of downy mildew. Older, fully expanded foliage was unaffected. Flowers could be infected with the fungus growing on the undersides of petals and resulting in slightly twisted, bent shapes. Symptomatic plants and cutflower stems were unmarketable. Hyaline conidiophores emerged from stomata, branched dichotomously (rarely trichotomously), and had branches ending in slender, curved branchlets that did not have swollen tips. Conidia were slightly brown, ovoid, mostly nonpapillate, and measured 28.5 to 40.0 × 19.0 to 28.0 μm. Oospores were not observed in plant tissue. On the basis of symptoms and morphology of the organism, the pathogen was identified as Peronospora radii (1,2). To prove pathogenicity, plants were spray inoculated with conidial suspensions, incubated for 24 h in a dew chamber (18 to 20°C), and then maintained in a greenhouse (22 to 24°C).After 18 to 20 days, symptoms and signs of downy mildew developed only on the newest foliage of inoculated plants, and the pathogen morphology matched that of the originally observed pathogen. Untreated control plants did not develop downy mildew. To our knowledge, this is the first report of downy mildew caused by P. radii on marguerite daisy in California and the United States. The pathogen has not been reported on other hosts in California. P. radii is found on marguerite daisy in England, Germany, Israel, Mexico, and the former Yugoslavia (1,2). References: (1) I. S. Ben-Ze'ev et al. Phytoparasitica 15:51, 1987. (2) O. Constantinescu. Sydowia Ann. Mycol. 41:79, 1989.
First Report of Blight on Ipomoea purpurea Caused by Phytophthora ipomoeae
Authors: Badillo-Ponce G. , Fernández-Pavía S. P. , Grünwald N. J. , Garay-Serrano E. , Rodríguez-Alvarado G. , Lozoya-Saldaña H. 
Published: May 2007

Several wild species of Ipomoea grow in the central highlands of Mexico. During the summer of 1999, in Metepec, Mexico, blighted leaves and petioles of Ipomoea purpurea were collected from diseased plants and placed in a moist chamber to induce sporulation. Sporangia that formed on the lesions were transferred with a piece of agar to selective rye agar medium (2). Phytophthora ipomoeae was consistently isolated. Species identification was based on sporangial and gametangial characteristics of five cultures grown on rye agar. Sporangia were mainly ellipsoid but occasionally ovoid, semipapillated, and deciduous with a short pedicel. All isolates were homothallic with smooth-walled and aplerotic oospores. Genotypic analysis for the allozymes Peptidase (Pep) and Glucose-6-phosphate isomerase (Gpi) indicated that all five isolates belonged to one genotype with alleles 78/78 (Pep) and 108/108 (Gpi). Morphological characteristics and the allozyme genotype correspond to the new, recently described species P. ipomoeae Flier & Grünwald (1) isolated from I. orizabensis (Pelletan) Ledeb. ex Steud. (I. tyrianthina) Lindl. and I. longepedunculata (Mart. & Gal.) Hemsl. Pathogenicity tests were carried out with leaves from greenhouse-grown I. purpurea plants. Detached leaves were inoculated with a suspension of 103 sporangia per ml and kept in a moist chamber at room temperature (17 ± 3°C). Lesions were observed between 7 and 15 days after inoculation and were characteristic of those observed in the field. The pathogen was reisolated from inoculated symptomatic tissue. To our knowledge, this is the first report of blight on I. purpurea caused by P. ipomoeae. References: (1) W. Flier et al. Mycol. Res. 106:848, 2002. (2) N. J. Grünwald et al. Phytopathology 91:882, 2001.
First Report of Downy Mildew Caused by Plasmopara helianthi Races 700 and 703 of Sunflowers (Helianthus annuus) in Italy
Authors: Tosi L. , Zazzerini A. 
Published: May 2007

Sunflower (Helianthus annuus L.) plants showing systemic downy mildew (Plasmopara helianthi Novot.) symptoms (stunting and leaf chlorosis) were collected during May and June 2001-2003 in fields located in four regions of central Italy (Umbria, Tuscany, The Marches, and Emilia-Romagna). Generally restricted, a low disease incidence (2 to 12%) was observed in fields planted with commercial hybrids. In the surveyed areas, higher field incidences (20 to 30%) of downy mildew were only observed where suitable climatic conditions occurred. To determine pathogen race variability of P. helianthi, 18 isolates (one for each field) were recovered directly from infected leaves showing sporulation or after 24 h of incubation in a humid chamber at room temperature. After increasing initial inocula on the susceptible cv. Ala, race identification of all isolates was determined by the whole-seedling immersion technique (2) on three sets of nine differential sunflower lines (three lines per each set): HA-304, RHA 265, RHA 274; PMI-3, PMI-17, 803-1; and HAR-4, QHP-1, HA 335 using triplet coding (1). All differential lines were tested twice with 40 seeds per replicate (three replicates per line). Twelve days after inoculation, plants were placed in a chamber maintained at 20°C and 100% relative humidity for 24 h and then evaluated for a susceptible (sporulation on cotyledons and/or first true leaves) or resistance (absence of sporulation) reaction. Races 700 and 703 were identified during the 3-year survey. Race 700 was recovered frequently (56% of isolates) from the Italian regions except Emilia-Romagna. Race 703 was not detected in Tuscany. Races 700 and 703 have been previously isolated in other European countries (3,4), but to our knowledge, this is the first report of the occurrence of either race in Italy. Our results confirm previous investigations and suggest that the restricted presence of downy mildew should be attributed to several factors: (i) lack of any source of resistance to both races in commercial hybrids; (ii) insufficient seed dressing with metalaxyl as observed on remnants of commercial hybrid treated seeds tested in laboratory analyses; and (iii) short rotation of cereals (often only 2- to 3-year interval) with sunflower crops. Although greenhouse tests showed most P. helianthi isolates were not controlled by metalaxyl seed treatment at the registered rate (2.1 g kg-1) loss of fungicide efficiency in fields has not yet been observed indicating that appropriate phytosanitary measures and proper seed treatment can provide control of sunflower downy mildew. References: (1) T. J. Gulya. Pages 76–78 in: Proc. 17th Sunflower Res. Workshop, Fargo, ND, 1995. (2) T. J. Gulya et al. Helia 14:11, 1991. (3) M. L. Molinero-Ruiz et al. Plant Dis. 86:736, 2002. (4) F. Virany and T. J. Gulya. Plant Pathol. 44:619, 1995.
First Report of Lettuce big-vein virus and Mirafiori lettuce virus in Chile
Authors: Rosales I. M. , Sepúlveda P. , Bruna A. 
Published: May 2007

Lettuce big-vein disease (BVD) is a serious virus disease of lettuce. Recent evidence has brought into question the role of Lettuce big-vein virus (LBVV) in the etiology of BVD, and suggested that Mirafiori lettuce virus (MiLV) and not LBVV is the causal agent of BVD (1,2). Lettuce plants (Lactuca sativa L.) with symptoms similar to those of BVD were observed during the winter of 2003 in open-field and hydroponic-grown lettuce plants located in the Chacabuco Province of central Chile. Symptomatic plants exhibited leaves with chlorotic vein banding that became ruffled and distorted. Symptoms were usually accompanied by reduced plant size and absence of head formation. Roots from symptomatic plants were analyzed by light microscopy-acid fuchsin staining. Zoosporangia and resting spores of Olpidium brassicae were identified on the basis of their morphology and structure. Additionally, soil transmission experiments were performed with 50 healthy lettuce seedlings replanted into contaminated soil collected from lettuce fields having symptomatic crops. After 3 weeks, one-half of the seedlings showed differing degrees of big-vein symptoms, and the presence of spores of O. brassicae was confirmed in the roots by light microscopy. Seedlings raised in sterilized soil showed no symptoms after the same period of time. On the basis of nucleotide sequences of LBVV and MiLV from the GenBank database, primers specific to the coat protein genes of each virus were designed as follows: MiLVV-CP1: 5′-CAAATCTGTCCACAATTCC-3′; MiLVV-CP2: 5′-TCTCACTTGAAAACCTTCC-3′; MiLVV-CP3: 5′-TTGCAACGTGATGAAACC-3′; MiLVV-CP4: 5′-AAAGAAGAGAAGCCTGTTCC-3′; LBVV-CP1: 5′-AAGCTTTCCGTACTGTCC-3′; LBVV-CP2: 5′-CCTTGATACAGTTTTTGACC-3′; LBVV-CP3: 5′-GTATGCTGATTTCTGTAGACC-3′; LBVV-CP4: 5′-TAGATGTTCTTCGCCACC-3′. The primers were used in reverse transcription-polymerase chain reaction (RT-PCR) assays with dsRNA as a template. Amplicons of the expected size were obtained in each of the five symptomatic plants analyzed, using each of the designated primer sets: MiLVV-CP1/MiLVV-CP2: 562 bp; MiLVV-CP3/MiLVV-CP4: 743 bp; LBVV-CP1/LBVV-CP2: 485 bp; and LBVV-CP3/ LBVV-CP4: 570 bp. No amplicons were obtained from healthy lettuce plants. The identity of both viruses was verified by cloning and sequencing of the amplicons. Nucleotide sequences were compared with those in the GenBank database. Sequences derived from the Chilean isolates resulted in identities of 87 to 97% for MiLV and 97 to 99% for LBVV. All samples analyzed were from the Chacabuco Province where 43% of the lettuce crops in Chile are grown. Thus, the impact that BVD may have on lettuce availability for local consumption may be significant. To our knowledge, this is the first report of Lettuce big-vein disease and Mirafiori lettuce virus infecting lettuce and the first report of BVD in Chile. References: (1) H. Lot et al. Phytopathology 92:288, 2002. (2) P. Roggero et al. Eur. J. Plant Pathol. 109:261, 2003.
First Report of Dollar Spot Caused by Sclerotinia homoeocarpa on Agrostis stolonifera in Argentina
Authors: Rivera M. C. , Wright E. R. , Goldring L. V. , Pérez B. A. , Barreto D. 
Published: May 2007

During the summer of 2000, circular, yellow-to-brown, blighted, 2- to 4-cm-diameter patches were observed on creeping bentgrass (Agrostis stolonifera) putting greens (cv. Pennlinks) maintained at a 4- to 5-mm height on a golf course in Pilar (Buenos Aires, Argentina). Symptomatic leaves had transverse chlorotic bands that sometimes extended to the tip with brown lesions inside the bands. A fungus was isolated from symptomatic tissue after surface sterilization with 2% bleach for 1 min and plating on 2% potato dextrose agar (PDA). The mycelium was fluffy and white. The culture turned olive to brown and developed black stromata on the lower side of the plate base after 2 weeks. Pathogenicity tests were performed on 2-month-old healthy plants of A. stolonifera (cv. Crenshaw) grown in sterilized sand. Recently cut, 14-mm-diameter plugs of A. stolonifera were placed in 22- × 17-cm plastic trays filled with a sterilized mixture of 50:50 soil/sand (vol/vol). Plants were maintained at a 7-mm height. Two sources of inoculum were prepared; one was cultured on PDA at 22 to 25°C for 10 days and the other was prepared by incubating in sterilized soil at room temperature for 14 days. Twenty pieces of 1-cm-diameter agar blocks containing mycelium were placed in each plug at the base of the plants. In the infested soil inoculation, 25 g of soil were distributed among the plants on the substrate surface. Control plants were treated with either sterile PDA pieces or noninfested soil. The trays were irrigated with sterilized distilled water, covered with polyethylene bags, and kept in a controlled environment chamber at 25°C with 12 h per day of fluorescent light for 30 days. Leaf chlorosis appeared 7 and 10 days after inoculation for the agar-plug and infested-soil methods, respectively. Leaf necrosis was observed at day 23. Controls remained asymptomatic. The inoculated fungus was reisolated from symptomatic leaf tissue. The pathogen was identified as Sclerotinia homoeocarpa (1,2). To our knowledge, this is the first report of Sclerotinia homoeocarpa causing dollar spot disease on Agrostis stolonifera in Argentina and the first report of a disease on golf courses in our country. References: (1) J. E. M. Mordue. Sclerotinia homoeocarpa. No. 618 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1979. (2) R. W. Smiley. Dollar Spot. Pages 14–16 in: Compendium of Turfgrass Diseases. The American Phytopathological Society, St. Paul, MN, 1983.
First Report of Occurrence of Papaya ring spot virus Infecting Papaya in Bangladesh
Authors: Jain R. K. , Nasiruddin K. M. , Sharma Jyoti , Pant R. P. , Varma A. 
Published: May 2007

Papaya (Carica papaya L.) is an important fruit crop in Bangladesh. During surveys conducted in Dhaka and Mymensingh regions from April to June 2003, >50% of papaya plants were observed to have leaf mottling, mosaic and mild distortion, and water-soaked streaks on petioles and stem, which are typical symptoms of Papaya ring spot virus (PRSV) infection. Electron-microscopic examination of negatively stained leaf-dip preparations from 10 symptomatic samples revealed the association of flexuous virus particles that were decorated with polyclonal antibodies raised to an isolate from India (PRSV-D). The identity of PRSV associated with the papaya disease in Bangladesh was further confirmed by reverse transcription polymerase chain reaction and sequence analysis (2). By using PRSV specific primers (2), the 3′-terminal region comprising a part of the nuclear inclusion b gene, the coat protein (CP) gene, and the untranslated region were amplified and sequenced (GenBank Accession No. AY423557). The CP gene consisted of 286 amino acids and the conserved regions common to the genus Potyvirus, such as WCIEN and QMKAA, were present. Like all known PRSV sequences (1), a stretch of glutamic acid and lysine repeats (EK region) after the aphid transmission motif (DAG) also was present. Comparative CP amino acid sequence analyses revealed that the virus infecting papaya in Bangladesh, designated as PRSV-Bd, shared 89 to 92% identity with PRSV isolates from India and 88 to 93% identity with isolates from other parts of the world. To our knowledge, this is the first report of occurrence of PRSV infecting papaya in Bangladesh. References: (1) M. F. Bateson et al. J. Gen. Virol. 83:2575, 2002. (2) R. K. Jain et al. Ann Appl. Biol. 132:413, 1998.
A Virus Related to Clover Yellow Mosaic Virus Found East of the Mississippi River in Verbena canadensis in Florida
Authors: Baker C. A. , Beckham K. , Hiebert E. 
Published: May 2007

In September 2002, several unthrifty Verbena canadensis ‘Homestead purple’ plants were received at the Division of Plant Industry in Gainesville, FL. Symptoms included very subtle yellowing and distortion or stunting of the younger leaves, symptoms that could be overlooked as a nutritional problem. Symptomatic leaves were ground in phosphate buffer and mechanically inoculated to a variety of plants that included Antirrhinum majus, Chenopodium amaranticolor, Datura stramonium, Gomphrena globosa, Pisum sativum, Trifolium pratense, T. repens, Vicia faba, and Vigna unguiculata. These hosts showed symptoms similar to those described for infection by Clover yellow mosaic virus (ClYMV) (3). In addition, the virus systemically infected Arachis hypogaea, Catharanthus roseus, C. quinoa, Nicotiana benthamiana, and healthy seed-grown Verbena × hybrida. No symptoms were seen in inoculated Zinnia elegans, N. glutinosa, N. clevelandii, Lycopersicon esculentum, Cucumis sativus, or Capsicum annuum. However, back inoculations of Cucumis sativus to C. amaranticolor gave typical local and systemic symptoms. Microscopic examination of leaf strips of infected V. faba revealed banded inclusions typical of the genus Potexvirus (1). Reverse-transcription polymerase chain reaction (RT-PCR) using degenerate primers for the genus Potexvirus (2) produced a 750-bp product that is the expected product for the genus Potexvirus. The RT-PCR product was cloned in pGem-T easy (Promega, Madison, WI) and sequenced. BLAST ( http://www.ncbi.nlm.nih.gov/ BLAST/ ) analysis of the sequence showed an 82% identity at the nucleotide level with the RNA polymerase gene of ClYMV. Leaf extracts of the original verbena, several inoculated hosts, and a known sample of ClYMV in N. benthamiana were tested in sodium dodecyl sulfate immunodiffusion (4) against antiserum to the degraded capsid protein of ClYMV. A reaction of identity was seen with infected samples but not with samples for comparable virus-free plants. To our knowledge, this is the first time this virus has been found in the eastern United States. It is not known how or if the presence of this noninsect transmitted virus in an ornamental will affect the agricultural, forage, or ornamental industries in the east or how widely distributed Verbena sp. infected with this virus may be at this time. References: (1.) R. G. Christie and J. R. Edwardson. Fla. Agric. Exp. Stn. Monogr. 9, 1994. (2.) A. Gibbs et al. J. Virol. Methods 74:67,1998 (3.) M. J. Pratt. Can. J. Bot. 39:655. 1961. (4) D. E. Purcifull and D. L. Batchelor. Fla. Agric. Ext. Stn. Bull. 788, 1977.
First Report of Sweet Pepper (Capsicum annuum) as a Natural Host Plant for Tomato chlorosis virus
Authors: Lozano G. , Moriones E. , Navas-Castillo J. 
Published: May 2007

Since 1997, epidemics of a tomato yellowing disease have occurred in the Málaga and Almería provinces of southern Spain. These epidemics have been associated with infections of Tomato chlorosis virus (ToCV) (genus Crinivirus, family Closteroviridae) (2). During the past few years, an increasing incidence of the disease was observed and it spread to new areas including eastern Spain and the Balearic and Canary Islands (G. Lozano, E. Moriones, and J. Navas-Castillo, unpublished results and [1]). In 1999, plants of sweet pepper (Capsicum annuum L.) exhibiting symptoms of interveinal yellowing, mild upward leaf curling, and stunting were observed in greenhouses of Almería that were heavily infested with the whitefly, Bemisia tabaci. Symptomatic plants were tested for the presence of the begomovirus, Tomato yellow leaf curl virus, a virus previously reported in sweet pepper (3) by molecular hybridization or polymerase chain reaction (PCR). Some of these plants tested positive. Total RNA extracts from the symptomatic plants were also analyzed for the presence of tomato criniviruses using reverse transcription (RT)-PCR with primers MA59 and MA60 for the HSP70h gene (2). A PCR DNA product of the expected size (587 bp) was obtained from several samples. The cloning and sequencing of the PCR product obtained from one of these samples confirmed the presence of ToCV, with a sequence 100% identical to the equivalent region of the first ToCV isolated from tomato in Málaga (2). Total RNA extracts from plants that tested positive using RT-PCR were also positive with molecular hybridization using a probe for the HSP70h gene of ToCV. To our knowledge, this is the first report of sweet pepper as a natural host of a tomato crinivirus, which may have important epidemiological consequences in regions where both crops are grown. Association between ToCV infection and specific symptoms observed in sweet pepper plants is under study. References: (1) M. I. Font et al. Bol. San. Veg. Plagas 29:109, 2003. (2) J. Navas-Castillo et al. Plant Dis. 84:835, 2000. (3) J. Reina et al. Plant Dis. 83:1176, 1999.
First Report of Root Rot and Stem Blight Caused by Phytophthora palmivora in Eustoma grandiflorum
Authors: Toppe B. , Aanonsen E. , Klemsdal S. 
Published: May 2007

Eustoma grandiflorum (Raf.) Shinn., commonly referred to as Lisianthus or Texas bluebell, is grown on a limited but increasing scale in Norwegian greenhouses. In autumn 1999, E. grandiflorum plants with brown rotten roots and wilting foliage were collected from a cut-flower production facility in southeastern Norway. Symptoms were difficult to distinguish from those caused by Pythium spp. or early attack of Fusarium spp. For diagnosis, root and stem segments surface sterilized by dipping in alcohol and hypochlorite were plated on potato dextrose agar. Phytophthora sp. was isolated consistently from diseased roots and stems. Suspected Phytophthora sp. isolates were transferred to selective agar medium containing hymexazol and identified by morphological characteristics and DNA sequence homology (1). The fungus was characterized by stellate mycelium, lack of oogonia in single culture, sympodial sporangiophores, and production of numerous papillate, ellipsoid sporangia that were caduceus with small pedicels in water. Optimum temperature for mycelium growth was 25 to 30°C, with limited growth at 10 and 35°C. The DNA sequence of the polymerase chain reaction amplified internal transcribed spacer (ITS1 and ITS2) regions of rDNA, confirmed the identification as P. palmivora. Pathogenicity studies were conducted by inoculating nine, 12-week-old E. grandiflorum plants grown in 10-cm pots with peat substrate at 24°C with artificial light (120 W/m2) for 10 h per day, with a zoospore suspension or an agar piece toward the plant stem. The pathogenicity study was repeated once. In both experiments, all plants except uninoculated controls, died within 3 weeks after inoculation. P. palmivora was reisolated from diseased plants. In later greenhouse experiments, more than 50% of plants showed disease symptoms when adding 1,000 zoospores of P. palmivora per pot. ‘Ecco Yellow’ was more susceptible than ‘Flamenco Purple’. The pathogen was as aggressive as Fusarium avenaceum in pathogenicity studies. Since E. grandiflorum is grown on a limited scale in Norway, we lack experience with the economic impact of this disease in the cut-flower industry. To our knowledge, this is the first report of P. palmivora in E. grandiflorum. Reference: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996.