bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bacterial Ring Rot of Potatoes Caused by Clavibacter michiganensis subsp. sepedonicus in Lithuania
Authors: Baranauskaite L. , Vasinauskiene M. 
Published: May 2007

Bacterial ring rot of potato (Solanum tuberosum L.) was observed for the first time in Lithuania from 1998 to 1999. The disease, caused by Clavibacter michiganensis subsp. sepedonicus, is considered one of the most important bacterial diseases of potato. Nearly all countries that produce potatoes report the presence of the bacterium (1). C. michiganensis subsp. sepedonicus is listed as an A2 quarantine pathogen by the European and Mediterranean Plant Protection Organization. The pathogen has a latent period that can last for several generations of potato production, thus increasing the risk for further dissemination of the disease. Plant wilting and tuber rotting, characteristic symptoms of the disease, were observed in various localities in Lithuania. The disease was found in 12 potato varieties. Disease incidence approached 5% in the field and 5 to 21% in storage. The presence of C. michiganensis subsp. sepedonicus in diseased as well as asymptomatic plant tissue was determined by immunofluorescence cell staining and enzyme-linked immunosorbent assay with the use of monoclonal and polyclonal antibodies, respectively. More than 350 potato samples were tested. Twenty-five samples tested positive by these methods. Pathogenicity tests of 30 samples were conducted on eggplant. Characteristic symptoms were found on 21 plants. The bacteria were reisolated on nutrient dextrose agar medium from 12 inoculated eggplants. For confirmation of six suspicious strains, polymerase chain reaction with a specific Cms50 primer set was employed (2). In three cases, positive results were obtained. References: (1) I. M. Smith and L. M. F. Charles, eds. 1998. Distribution of Maps of Quarantine Pests for Europe. CAB International, Wallingford, U.K. (2) D. Mills et al. Phytopathology 87:853, 1997.
First Report of Pepino mosaic virus in Canada and the United States
Authors: French C. J. , Bouthillier M. , Bernardy M. , Ferguson G. , Sabourin M. , Johnson R. C. , Masters C. , Godkin S. , Mumford R. 
Published: May 2007

During the winter of 2000, tomatoes (Lycopersicon esculentum) with a bright yellow leaf mosaic were observed in a commercial greenhouse in southern Ontario, Canada. Examination of leaf extracts, using leaf dips and immunosorbent absorption electron microscopy (ISEM), showed flexuous rods consistent with the potexvirus group. Polyclonal antibodies raised against the original Peruvian Pepino mosaic virus (PepMV) isolate (1) and commercial antibodies obtained from Deutsche Sammlung von Mikro-organismen und Zellkulturen (DSMZ), GmbH, Braunsweig, Germany, and Plant Research International (PRI), Wageningen, the Netherlands, were used in ISEM. Leaves tested positive in double-antibody sandwich-enzyme-linked immunosorbent assay (ELISA) with antibodies from DSMZ and PRI. A triple-antibody sandwich-ELISA obtained from Adgen Ltd. (Nellies Gate, UK) gave similar results. Potato virus X did not react with PepMV antiserum in ELISA. Positive PepMV ELISA controls were a U.K. and a Dutch isolate supplied by R. Mumford and R. A. A. van Vlugt, respectively, and DSMZ. Using primers generated from a sequence of the RNA polymerase region of a U.K. PepMV isolate (R. Mumford, unpublished data), a reverse transcription-polymerase chain reaction test showed the expected 312-bp amplicon for the Canadian, Dutch, and U.K. isolates. The primer sequences used were forward 5′ CTA TTA CAA CTC CGG AAG CCA 3′ and reverse 5′ TGG TCT GGC CAG GCT TTG AC 3′. The three isolates were maintained in tomato cv. Bush Beefsteak. When mechanically inoculated on L. esculentum cv. Rapsodie, the Canadian isolate caused a bright yellow mosaic in 1 to 2 weeks, while the two European isolates caused a faint yellow mosaic and mild puckering of the leaves. When mechanically inoculated on 17 indicator plants, the Canadian isolate had a host range similar to the U.K. isolate. The most striking difference in symptoms occurred in L. pimpinellifolium, in which the Canadian isolate caused a yellow mosaic, the Dutch isolate caused no symptoms, and the U.K. isolate caused a marked puckering of the leaves, suggesting virus strain differences among the isolates. Tomato fruits originating from the United States were collected during border inspections by the Canadian Food Inspection Agency and tested for PepMV by ELISA with antisera from DSMZ. PepMV was not detected in 7 samples from California, but was detected in 6 of 12 samples from Colorado, 6 of 7 samples from Arizona, and 1 of 5 samples from Texas. PepMV was originally isolated from pepino (Solanum muricatum) in Peru in 1980 (1) and subsequently from tomato in the Netherlands in 1999 (2). To our knowledge, this is the first report of PepMV in North America. References: (1) R. Jones et al. Ann. Appl. Biol. 94:61, 1980. (2) R. A. A. van Vlugt et al. Plant Dis. 84:103, 2000.
First Record of Barley yellow striate mosaic virus and Cereal yellow dwarf virus-RPV Infecting Wheat in Uzbekistan
Authors: Makkouk K. M. , Kumari S. G. , Kadirova Z. , Zueva A. 
Published: May 2007

A preliminary survey to identify virus diseases affecting wheat in Uzbekistan was conducted during May 2001. The survey covered 12 wheat fields from 2 cereal-growing regions (Tashkent-Angren and Tashkent-Samarkand). A total of 250 wheat samples with symptoms suggestive of virus infection were collected and tested for the presence of nine viruses by tissue-blot immunoassay (TBIA) (1) at the Virology Laboratory of ICARDA, Aleppo, Syria, using the following antisera: monoclonal antibodies for Cereal yellow dwarf virus-RPV (CYDV-RPV) (ATCC PVAS-669 [American Type Culture Collection, Manassas, VA]) and Barley yellow dwarf virus-MAV (BYDV-MAV) (ATCC PVAS-673); and polyclonal antibodies for BYDV-SGV and BYDV-RMV (3); BYDV-PAV, Barley stripe mosaic virus, and Wheat streak mosaic virus (from Virology Laboratory, ICARDA); Wheat dwarf virus (provided by J. Vacke, Research Institute of Crop Production, Prague, Czeck Republic); and Barley yellow striate mosaic virus (BYSMV) isolated from Lebanon (2). The most common virus present was BYDV-PAV (detected in 12% of the 250 samples tested), followed by BYDV-SGV (10.8%), BYSMV (5.6%), BYDV-RMV (2.4%), BYDV-MAV (2%), and CYDV-RPV (1.2%). CYDV-RPV was detected in three fields; one field was 50 km southeast of Tashkent, and the other two fields were between Tashkent and Samarkand. The majority of BYSMV-positive samples originated from the same field, ≈40 km northeast of Samarkand. Field symptoms of BYSMV-infected plants included yellow flag leaf and stunting. All samples that produced a positive reaction to BYSMV-Lebanon antiserum were tested against four other rhabdovirus antisera: BYSMV-Italy, BYSMV-Morocco, Cereal chlorotic mottle virus, and American wheat striate mosaic virus. Serological tests showed that 100% of the samples reacted strongly with BYSMV-Italy and BYSMV-Morocco. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by western blots, extracts from BYSMV-infected plants were found to contain 66- and 47-kDa structural proteins, typical of G and N proteins of rhabdoviruses, both of which reacted strongly with BYSMV-Italy antiserum. To our knowledge, this is the first report of BYSMV and CYDV-RPV in Uzbekistan. References: (1) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994. (2) K. M. Makkouk et al. Plant Dis. 85:446, 2001. (3) G. N. Webby and R. M. Lister. Plant Dis. 76:1125, 1992.
First Report of Cucumber leaf spot virus in Spain
Authors: Segundo E. , Janssen D. , Velasco L. , Ruiz L. , Cuadrado I. M. 
Published: May 2007

Cucumber leaf spot virus (CLSV), reclassified as a species in the new genus Aureusvirus (family Tombusviridae) (1), has ≈30-nm isometric particles with a ≈4.4-kb positive-sense, single-stranded RNA. CLSV is transmitted by the chytrid fungus Olpidium bornovanus. The virus has been reported in Germany, Great Britain, Greece, Jordan, and Saudi Arabia. During the fall of 2000, abundant chlorotic spots with necrotic centers were observed on the leaves of cucumber plants grown in a commercial greenhouse in Granada (southeastern Spain). When sap from collected leaves was used to mechanically inoculate cucumber, symptoms were reproduced and were suggestive of CLSV. Based on the nucleic acid sequence of CSLV (2), the following specific primers were designed: CLSVU1440 (5′-AAGGTAGGGGAGATCTTG-3′) and CLSVA2160 (5′-GCTTCGGCTGATTCTGA-3′). When used in reverse transcription-polymerase chain reactions (RT-PCR), leaves expressing symptoms yielded amplification products of the expected size (720 bp). These products were cloned into a pGEM-T vector and sequenced (GenBank Accession No. AY038365). The similarity of the nucleic acid and derived amino acid sequences with the one published for CLSV (2) was 94.5 and 99.1%, respectively. The amino acid sequence was 86% identical to that of Pothos latent virus (GenBank Accession No. AJ243370). Ten cucumber plants grown in vermiculite supplemented with rhizosphere soil (1/30, vol/wt) from infected plants developed symptoms on leaves after 1 month and were positive for CLSV when leaf and root tissues were analyzed by RT-PCR and Southern blot hybridization. Plants grown in vermiculite alone did not become infected with CLSV. Microscopic examination of root tissue revealed O. bornovanus only in infected plants. To our knowledge, this is the first record of CSLV in Spain. References: (1) G. P. Martelli et al. Arch. Virol. 143:1847, 1998. (2) J. S. Miller et al. Virus Res. 52:51, 1997.
First Report of Resistance to Benomyl Fungicide in Sclerotinia sclerotiorum
Authors: Gossen B. D. , Rimmer S. R. , Holley J. D. 
Published: May 2007

Benomyl fungicide (Benlate) is used worldwide to control ascomycete pathogens, but resistance has developed in several pathogen populations (1). On the Canadian prairies, benomyl is used to reduce injury caused by Sclerotinia sclerotiorum (Lib.) de Bary on canola (Brassica napus, B. rapa) and alfalfa (Medicago sativa) seed crops. To determine if populations are resistant to benomyl, isolates of S. sclerotiorum collected from 15 fields (12 alfalfa and 3 canola, one isolate per field) in 2000 were grown on potato dextrose agar amended with benomyl at 0, 0.05, 0.5, 5, 50, and 500 mg/liter. Plugs of mycelium from the margin of an actively growing colony were placed in the center of a 10-cm-diameter petri dish containing 15 ml of test medium and incubated on a laboratory bench. Linear growth (mean of maximum width and right angle) of each colony (three replicates each) was measured after 5 to 6 days. The growth of isolates from 13 fields was inhibited by low concentrations of benomyl (EC50 < 8 mg/liter), but two isolates were very resistant (EC50 > 200 mg/liter). Resistant cultures were isolated from infected canola plants in the only two fields in the study in which reduced efficacy of benomyl was suspected. The distribution and importance of benomyl-resistant populations of S. sclerotiorum in the region remains to be determined. Reference: (1) T. R. Pettitt et al. Mycol. Res. 97:1172, 1993.
First Report of Erysiphe sedi on Sedum spectabile in North America
Authors: Kiss L. , Daughtrey Margery L. 
Published: May 2007

Since 1997, powdery mildew infections have been repeatedly observed on Sedum spectabile plants, cv. Autumn Joy, grown as ornamentals in commercial greenhouses in New York. Circular patches of gray mycelia appeared and spread on upper and occasionally on lower leaf surfaces followed by necrosis of the leaf tissues and defoliation. The new disease reduced the market value of the infected ornamentals and required chemical control. The pathogen produced conidia singly on 2- to 3-celled conidiophores occurring on the ectophytic hyphae. Conidia were subcylindrical, measured 27 to 36 μm × 13 to 17 μm, and contained no fibrosin bodies. Germinating conidia produced a short germ tube, 5 to 30 μm, terminating in a lobed appressorium. Hyphal appressoria were lobed to multi-lobed, opposite or spread along the hyphae. Cleistothecia were not found. Based on conidial characteristics, the pathogen was identified as Erysiphe sedi Braun. To confirm pathogenicity, potted healthy S. spectabile plants were placed near infected plants in the greenhouse. In addition, detached S. spectabile leaves were inoculated with the pathogen by touching them to powdery mildew colonies and then placed in plates filled with one layer of polystyrene balls floated in water. Plates were covered and kept in the laboratory. Uninfected potted plants kept in another greenhouse and noninoculated detached leaves served as controls. After 1 week, powdery mildew appeared on all infected plants and leaves exposed to or inoculated with the pathogen. The pathogen was morphologically identical to the original fungus. No symptoms were observed on the controls. E. sedi is a common Asiatic powdery mildew species infecting many crassulaceous plants (1,2) and was introduced to Eastern Europe from Asia (2). To our knowledge, this is the first report of E. sedi in North America. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fisher Verlag, Jena, 1995.
First Report of Natural Infection by “Candidatus Phytoplasma brasiliense” in Catharanthus roseus
Authors: Montano H. G. , Dally E. L. , Davis R. E. , Pimentel J. P. , Brioso P. S. T. 
Published: May 2007

Catharanthus roseus (L.) G. Don (periwinkle) is well known as an experimental host for diverse phytoplasmas that are artificially transmitted to it through the use of dodder (Cuscuta sp.), laboratory vector insects, or grafting. However, few phytoplasma taxa have been reported in natural infections of C. roseus, and the role of C. roseus in phytoplasma dissemination and natural disease spread is not clear. In this study, naturally diseased plants of C. roseus exhibiting yellowing and witches' broom symptoms indicative of phytoplasma infection were observed throughout the year in the state of Rio de Janeiro, Brazil. Shoots and leaves of four diseased plants were assayed for the presence of phytoplasma DNA sequences by nested polymerase chain reactions (PCR) as previously described (2,3). Phytoplasma rDNA was amplified from diseased periwinkle plants in PCR primed by primer pair P1/P7 and was reamplified in nested PCR primed by primer pair R16F2n/R16R2 (F2n/R2). The results indicated the presence of phytoplasma in all four diseased plants. Phytoplasma identification was accomplished by restriction fragment length polymorphism (RFLP) analysis, using 11 restriction enzymes, of 16S rDNA amplified in PCR primed by F2n/R2. Phytoplasmas were classified according to the system of Lee et al. (1). On the basis of collective RFLP patterns of 16S rDNA, the phytoplasma infections in the four periwinkle plants could not be distinguished from one another. Furthermore, the collective RFLP patterns were indistinguishable from those reported previously for hibiscus witches' broom phytoplasma, “Candidatus Phytoplasma brasiliense” (2). The phytoplasma found in C. roseus, designated strain HibWB-Cr, was classified in group 16SrXV (hibiscus witches' broom phytoplasma group). HibWB-Cr is tentatively considered a new strain of “Ca. P. brasiliense”. C. roseus is the first known, naturally diseased alternate plant host of “Ca. P. brasiliense”. The present study identified strain HibWB-Cr in Rio de Janeiro State, where hibiscus witches' broom disease is prevalent (2). How this economically important disease of hibiscus spreads is not known. Our findings raise the possibility that a polyphagous insect vector is involved in the natural transmission of “Ca. P. brasiliense” and that C. roseus or other plant species serve as reservoirs for the spread of this phytoplasma taxon. References: (1) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (2) H. G. Montano et al. Int. J. Syst. Evol. Microbiol. 51:1109, 2001. (3) H. G. Montano et al. Plant Dis. 84:429, 1999.
First Report of the Prevalence of Benzimidazole-Resistant Isolates in a Population of Cylindrocladium pauciramosum in Italy
Authors: Polizzi G. , Vitale A. 
Published: May 2007

Cylindrocladium pauciramosum C.L. Schoch & Crous (teleomorph Calonectria pauciramosa C.L. Schoch & Crous), described as a member of the Cylindrocladium candelabrum Viégas complex (4), was recently reported from Europe (3). In southern Italy, the fungus has caused extensive losses, and chemical control measures are necessary, especially in ornamental nurseries. Several researchers have found benzimidazole fungicides to be effective for control of different species of Cylindrocladium, however, in fungicide trials conducted on myrtle plants infected by C. pauciramosum, benomyl was ineffective (2). Another study showed that mycelial growth of six isolates was completely inhibited by carbendazim at a concentration of 1 μg a.i./ml whereas, concentrations of 10, 100, and 500 μg a.i./ml did not completely inhibit growth of four isolates (1). To examine benzimidazole resistance in C. pauciramosum, 200 single-conidia isolates were tested. These were collected during 1996 and 1997 from several symptomatic hosts in different nurseries located in Sicily and Calabria and identified through morphological characteristics as well as mating-type studies with tester strains. Sensitivity to benomyl was determined by plating mycelial plugs on potato dextrose agar (PDA) amended with benomyl at 1, 10, 100, and 500 μg a.i./ml. For 20 benomyl-resistant isolates, fungal growth was also determined at the same concentrations on carbendazim-amended PDA. Sensitivity was expressed as the minimum inhibitory concentration (MIC) (the lowest fungicide concentration that completely prevented fungal growth). Isolates that did not grow on benzimidazole-amended PDA were classed as sensitive. Isolates were considered resistant to benzimidazole if MIC values were greater than 1 μg a.i./ml. Of the 200 isolates tested, 58% were resistant to benomyl. The benomyl-resistant isolates tested for carbendazim sensitivity were cross-resistant to carbendazim. Most resistant isolates grew in the presence of benomyl at 500 μg a.i./ml. On agar culture, the isolates were either the fast-growing or slow-growing type. The slow-growing phenotype appears to be related to the higher level of resistance (500 μg a.i./ml). On the basis of these data, the use of benzimidazole for the control of this pathogen should be seriously questioned. To our knowledge, this is the first report of the prevalence of benzimidazole resistance in a population of C. pauciramosum. References: (1) G. Polizzi. Inf. Fitopatol. 11:39, 2000. (2) G. Polizzi and A. Azzaro. Petria 6:117, 1996. (3) G. Polizzi and P. W. Crous. Eur. J. Plant Pathol. 105:407, 1999. (4) C. L. Schoch et al. Mycologia 91:286, 1999.
First Report of Powdery Mildew Caused by Podosphaera leucotricha on Prunus africana in Kenya
Authors: Mwanza E. J. M. , Waithaka S. K. , Simons S. A. 
Published: May 2007

Prunus africana, formerly known as Pygeum africanum, is widely distributed in moist, tropical Africa and produces durable timber. Extracts from its bark are used in treatment of prostate disorders. Powdery mildew was observed on nursery-grown seedlings of P. africana in Kenya (Nyeri, Kiambu, and Kericho districts) in the dry seasons of 1998, 1999, and 2000. White ectotrophic mycelial growth was observed on leaves. The fungus caused stunting, distortion of leaves, surface necrosis of invaded tissues, and general decline in growth of seedlings that led to premature leaf fall and death. Invaded leaflets wilted and dropped, leaving behind a bare stem. The primary mycelium was hyaline, with no secondary brown mycelium. The conidial state was conspicuous, with conidia produced in chains. Appressoria were unlobed and nipple shaped. Conidiophores were straight and three-celled, measuring 75 to 112 μm. Conidiophore foot cells were topped by a longer cell and one or two shorter cells measuring 35 to 77 μm. Conidia had fibrosin bodies, were ovoid, and measured 27 to 30 × 17 to 18 μm. The fungus was identified by the International Mycological Institute IMI (W6496) as Podosphaera leucotricha (Ellis & Everh.) E. S. Salmon. Infected leaves of P. africana were deposited at the East African Herbarium, National Museums of Kenya (Accession No. KM-KEFRI/446/2001). Pathogenicity was confirmed by inoculating seedlings of P. africana by gently pressing infected leaves with abundant sporulation onto healthy leaves. The plants were then incubated under moist conditions for 48 h and thereafter maintained in a glasshouse. After 15 days, powdery mildew symptoms developed on seedlings. Examination of leaves confirmed that they were infected with Podosphaera leucotricha. Uninoculated control plants were free of powdery mildew. To our knowlege, this is the first report of Podosphaera leucotricha as a pathogen of P. africana. Reference: 1. H. J. Boesewinkel. Bot. Rev. 46:167, 1980.
First Report of Frog Skin Disease in Cassava (Manihot esculenta) in Venezuela
Authors: Chaparro-Martínez E. I. , Trujillo-Pinto G. 
Published: May 2007

Frogskin disease (FSD) is a disease of clonally propagated cassava (Manihot esculenta Crantz) and has been reported to reduce cassava yields significantly in South America (1). FSD is caused by an uncharacterized virus that is restricted to South America. The evidence indicates FSD is transmitted by stem cuttings and graft (3). However, little information is available on its distribution and incidence in Venezuela. Eighty-seven samples with virus-like symptoms were collected with the help of technical staff and producers in cassava-producing states: Amazonas (1 sample), Aragua (7 samples), Barinas (35 samples), Cojedes (8 samples), Monagas (19 samples), and Portuguesa (17 samples). In these states, the average daytime temperature was 26°C, but the average was higher (>28°C) during the dry season. Samples were collected during the rainy season because high temperatures and dry field conditions appeared to suppress symptom expression, while cooler conditions tended to favor symptom development (2). Roots of sampled cassava plants were examined for the presence of FSD. A single 70- to 80-cm-long stem cutting was taken from each plant and subdivided into four pieces. Two pieces were used as rootstocks in graft-inoculation tests with Secundina scions for FSD detection, and two pieces were potted in sterilized soil to be used in other tests. All potted and grafted plants were kept in the Vegetable Virology Laboratory of the Faculty of Agronomy (Universidad Central de Venezuela), at an average temperature of 24°C and 80% relative humidity. FSD-infected plants were identified by mosaic symptoms on Secundina scions and the presence of 80-nm spherical viral particles. Most FSD-infected cultivars expressed only root symptoms. However, in the case of Secundina cvs. MCOL 22 and MCOL 113, foliar symptoms were also detected (1). FSD was found in a simple infection in one cassava sample from Aragua State (14.3% incidence, 1 of 7 samples) and in four cassava samples from Barinas State (11.4% incidence, 4 of 35 samples) associated with Cassava virus X (detected by double-antibody sandwich enzyme-linked immunosorbent assay). To our knowledge, this is the first report of FSD detection in Venezuela. References: (1) E. A. Frison et al. Informe Anual. CIAT, Cali, Colombia, 1995. (2) B. L. Nolt et al. Plant Pathol. 41:384, 1992. (3) Technical Guidelines for the Safe Movement of Cassava Rome. FAO/IBPGR. p. 10-27, 1991.