bluuebunny/crossref_metadata_2025 huggingface dataset:
First Report of Cucumber leaf spot virus in Poland
Authors: Pospieszny H. , Cajza M. , Plewa R.
Published: May 2007

During April 2003, four young cucumber plants with slight stunting and delay of flowering were found in two commercial greenhouses in the Wielkopolska Region in Poland. Sporadically, chlorotic spots, sometimes with necrotic centers, were observed on the leaves of plants. Later, symptoms were less recognizable or they disappeared completely. Crude sap from symptomatic leaves of Cucumis sativus was used for mechanical inoculation of various plant species. The virus caused local and systemic infections on Cucumis sativus, Nicotiana benthamiana, and N. clevelandii and induced local necrotic lesions only on Chenopodium quinoa, C. amaranticolor, C. ficifolium, C. murale, Petunia hybrida, Cucurbita melo, Zinnia elegans, and Spinacia oleracea. No symptoms were seen in inoculated N. tabacum, N. glutinosa, Lycopersicon esculentum, Capsicum annuum, Physalis floridana, Phaseolus vulgaris, and Cucurbita pepo. Symptoms and host range were similar to those described for infection by Cucumber leaf spot virus (CLSV) (1). Electron microscopic examination of negatively stained leaf-dip preparation from infected plants showed spherical virus particles (approximately 30 nm). Total RNA extracted from symptomatic C.sativus and N. benthamiana plants, and RNA extracted from purified virus preparations were tested using reverse transcription-polymerase chain reaction (RT-PCR) with specific primers designed to amplify a fragment of the RNA-dependent RNA polymerase gene (4). RT-PCR products were sequenced with CEQ DTCS dye terminator cycle sequencing kit and the CEQ 2000 DNA Analysis System (Beckman Coulter, Inc., Fullerton, CA). The 664-nt amplicon sequence (GenBank Accession No. AY571334) had 95% nucleotide and 98% amino acid sequence identity with the Spanish CLSV isolate (GenBank Accession No. AY038365) (4) and 98 and 99% identity, respectively, with another CLSV isolate (3). The nucleic acid sequence of the Polish CLSV isolate was 81 to 84% identical to the equivalent region of two isolates of Pothos latent virus, another aureusvirus (GenBank Accession No AJ243370 and X87115) and had 86% identity with the amino acid sequence of both isolates. To our knowledge, this is the first report of CLSV in Poland. The virus was previously reported in Germany, Great Britain, Jordan, Greece, Saudi Arabia, Spain, and Bulgaria (1,2,4). CLSV is a member of the genus Aureusvirus, formerly Carmovirus (family Tombusviridae). In the first half of 2004, no cucumber plants testing positive for CLSV were found. This incidental occurrence of CLSV indicates that the virus is not a significant threat to cucumber in Poland at this time.

References: (1) A. Brunt et al. Cucumber leaf spot virus. Viruses of Plants.Descriptions and Lists from the VIDE Database. CAB International, 1996. (2) D.Kostova et al. J. Plant Pathol. 83:147, 2001. (3) J. S. Miller et al. Virus Res. 52:51, 1997. (4) E. Segundo et al. Plant Dis. 85:1123, 2001.
First Report of Peronospora parasitica on Wild Rocket (Diplotaxis tenuifolia) in Italy
Authors: Garibaldi A. , Minuto A. , Gullino M. L.
Published: May 2007

Several species of Diplotaxis (D. tenuifolia, D. erucoides, and D. muralis), known as wild rocket, are now widely cultivated in Italy. Wild rocket is used in Mediterranean cuisine as salad, a component of packaged salad products, and as a garnish for food. During the fall of 2002, a foliar disease of D. tenuifolia was observed in the field or greenhouse on several commercial farms in the Liguria Region of northern Italy. Symptoms appeared as small, irregular, dark brown-to-black speckling on the adaxial surfaces of leaves. The speckled areas sometimes expanded into larger spots. These symptoms were followed by leaf yellowing and the appearance of sporangiophores and sporangia on the lower and upper leaf surfaces. Sporangiophores were dichotomously branched with slender curved tips. Sporangia were ovoid, measuring 20 to 28 (average 22) μm long and 15 to 25 (average 19) μm wide. The causal agent of the disease was identified as Peronospora parasitica (3). Pathogenicity was established by inoculating 10 30-day-old plants of D. tenuifolia grown in pots in a peat/pumice/clay/composted bark mix (60:20:10:10), with a conidial suspension (102 conidia per ml). Ten noninoculated plants maintained under the same conditions served as the control. Plants were maintained in a glasshouse at air temperatures ranging between 10 and 26°C (average 16°C) and relative humidity at 85%. The pathogenicity test was done twice. Downy mildew symptoms developed within 12 days, and the same fungus was observed on inoculated plants. Noninoculated plants did not develop symptoms. To our knowledge, this is the first report of P. parasitica on D. tenuifolia in Italy. P. parasitca has been reported as the causal agent of downy mildew on D. muralis in England (1) and on cultivated rocket (Eruca sativa) in California (2).

References: (1) J. Fraymouth. Trans. Br. Mycol. Soc. 39:79, 1956. (2) S. T. Koike. Plant Dis. 82:1063, 1998. (3) D. M. Spencer. The Downy Mildews. Academic Press. New York, 1981.
Analysis of Pathotypes of Colletotrichum lindemuthianum Found in the Central Region of Mexico and Resistance in Elite Germ Plasm of Phaseolus vulgaris
Authors: González-Chavira Mario , Guerra Raúl Rodríguez , Hernández-Godínez Fernando , Acosta-Gallegos Jorge A. , de la Vega Octavio Martínez , Simpson June
Published: May 2007

The pathotypes of 17 isolates of Colletotrichum lindemuthianum from the central region of Mexico were characterized to determine the genetic relationship among isolates from this region and other regions of Mexico, and to evaluate the resistance present in the elite germ plasm collection of Phaseolus vulgaris at INIFAP. Eight pathotypes were identified, including pathotype 292, which is reported for the first time in Mexico. The lack of isolates infecting cultivar TU carrying the Co-5 resistance gene suggests that this cultivar is a useful source of resistance. Six pathotypes produced susceptible reactions on only differential cultivars of Middle American origin, one pathotype on a single cultivar of Andean origin, and one pathotype on cultivars of both Middle American and Andean origin. Comparison of amplified fragment length polymorphism (AFLP) genotypes of 21 isolates confirmed suggestions that populations of C. lindemuthianum are comprised of asexually reproducing clonal lineages. Analysis of five different pathotypes of C. lindemuthianum on 21 elite genotypes of P. vulgaris identified four genotypes from different races of P. vulgaris resistant to all five pathotypes. This information will allow breeders and farmers to select the resistant genotypes most suited to their needs.
First Report of Cytospora Canker Caused by Cytospora chrysosperma on White Poplar in Israel
Authors: Madar Z. , Solel Z. , Kimchi M.
Published: May 2007

A new disease, causing death of mature white poplar trees (Populus alba L.), was observed in Hulla Valley in northern Israel in the summer of 2002. The affected branches turned yellowish brown, and the inner bark turned black. The bark dried out and separated from the underlying wood. Later, copious, dark pycnidia developed on the dead bark. The pycnidia had a diameter of 650 µm (n = 50), ranging 600 to 800 µm. Under moist conditions, spore masses oozed out in long, reddish brown, coiled tendrils. The spores were hyaline, one-celled, and slightly curved, 1.1 × 5.5 µm (5.0 to 6.0 µm) (n = 100), and somewhat smaller than those reported by Schreiner (1). A herbarium specimen was deposited at the U.S. National Fungus Collections (BPI 843390). Isolations made from affected branches yielded colonies of Cytospora chrysosperma (Pers.:Fr.)Fr. with a whitish orange mycelium that turned dark green 11 days later. Its growth rate on potato dextrose agar at 25°C was 7.1 mm per day. Exposure to daylight induced pycnidial development after 3 to 4 weeks. Inoculation of eight 1-year-old seedlings of white poplar and willow (Salix acmophylla Boiss) proved the pathogenicity of several isolates of C. chrysosperma. The average canker length at 28 days after inoculation was 28.0 and 14.5 cm on white poplar and willow, respectively, indicating the higher susceptibility of P. alba. No cankers developed on the control seedlings. Reisolations from inoculated plants yielded C. chrysosperma. To our knowledge, this is the first report of Cytospora canker on white poplar in Israel.

Reference: (1) E. J. Schreiner. Am. J. Bot.18:1, 1931.
Patterns of Virulence Diversity in Puccinia triticina on Wheat in Egypt and the United States in 1998-2000
Authors: McVey D. V. , Nazim M. , Leonard K. J. , Long D. L.
Published: May 2007

Frequent epidemics of leaf rust in Egypt have been attributed to the appearance of new races virulent on commonly grown wheat cultivars. In 1998, 1999, and 2000, 726 isolates of Puccinia triticina collected in Egypt were tested on a set of 20 single Lr gene differential wheat lines, and 160 races were identified. Three races, MBDLQ, MCDLQ, and TCDMQ, were found in Egypt in all 3 years. Race MCDLQ occurred at >20% frequency each year. Virulences to wheat lines with Lr1, 3, 10, 14b, 15, 17, 23, and 26 occurred at >45% each year. Seven races found in Egypt also were found in either Israel, Sudan, Turkey, or Romania in 1998 or 1999, although the one race common to Sudan and Egypt was rare in Egypt (only 1 year, <1%). Four races found in Israel also were found in Egypt, and the similarity of virulence frequencies in Israel and Egypt indicate at least some exchange of inoculum. Romania and Turkey did not appear to be major sources of inoculum for leaf rust epidemics in Egypt. The level of genetic diversity in leaf rust collections in Egypt in 1998 to 2000 was similar to that of collections from the Southern and Central Plains of the United States in 1998 to 2000. The high diversity of races and the recurrence of common races in each year in Egypt as in the Southern and Central Plains of the United States is consistent with oversummer survival of P. triticina within Egypt or in a neighboring country. The buildup of races virulent on cultivars with the most commonly used Lr genes for resistance in Egypt also is consistent with year-round survival within Egypt or cyclical exchange of inoculum between Egypt and a neighboring country.
Effect of Sclerotinia Stem Rot on Yield of Soybean Inoculated at Different Growth Stages
Authors: Danielson G. A. , Nelson B. D. , Helms T. C.
Published: May 2007

The effects of Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, on yield of soybean were evaluated in the field with two cultivars in maturity group 0. Plants were inoculated at two growth stages, R3 and R5, using two inoculation methods. Seed weight, seed and pod numbers, seed protein, and oil content were measured. The effects of disease on yield were variable. Disease resulted in significant seed weight loss, with reductions per diseased plant ranging from 18.8 to 38.6%. The estimated yield loss per 10% disease incidence ranged from 83.2 to 229.0 kg/ha, with an average loss of 136.6 kg/ha for four field experiments. A reduction in the number of seeds and pods per plant and seed oil content occurred in some, but not all, experiments. Seed protein was not affected. When disease reduced seed weight, seed and pod numbers, or oil content, there was no growth stage × treatment interaction in the experiments, indicating that inoculation at R5 compared with R3 had a similar effect on yield.
First Report of White Pine Blister Rust on Rocky Mountain Bristlecone Pine
Authors: Blodgett J. T. , Sullivan K. F.
Published: May 2007

White pine blister rust caused by Cronartium ribicola was introduced into North America in the early 20th century and is spreading throughout the range of five-needle pines. In northern Colorado, this pathogen was first observed in 1998 on limber pine (Pinus flexilis) (1). It has not been reported on Rocky Mountain or Great Basin bristlecone pine (Pinus aristata and P. longaeva, respectively) in nature. However, Rocky Mountain bristlecone pine is susceptible to the disease when artificially inoculated (2). In October 2003, a Rocky Mountain bristlecone pine was found infected with C. ribicola in the Great Sand Dunes National Monument, Alamosa County, Colorado. Seven branch cankers were observed on the tree. Cankers ranged in length from 15 to 41 cm and were estimated to be approximately 5 to 7 years old. Distinct C. ribicola branch symptoms were observed, including flagging, spindle-shaped swellings, and 6 mm long aecial scars. A branch was deposited at the Colorado State Herbarium. Microscopic examination of spores within remnant aecial blisters revealed aeciospores characteristic of C. ribicola (yellow-orange, ellipsoid, verrucose, and 19 × 25 μm). Cankers were only observed on one bristlecone pine. However, most limber pines in the area were infected with C. ribicola, including a limber pine less than 1 m from the infected bristlecone pine. To our knowledge, this is the first report that shows Rocky Mountain bristlecone pine can become infected naturally, and the pathogen is further south in Colorado on limber pine than previously reported. These observations suggest the need for a more complete investigation of this disease on bristlecone pines.

References: (1) D. W. Johnson and W. R. Jacobi. Plant Dis. 84:595, 2000. (2) B. R. Stephan, Allg. Forst Z. 28:695, 1985.
Identification of Fungi and Fungal Pathogens Associated with Hypolixus haerens and Decayed and Cankered Stems of Amaranthus hybridus
Authors: Blodgett J. T. , Swart W. J. , Louw S. vdM.
Published: May 2007

Discoloration, cankers, and decay in branches, stems, and root collars of Amaranthus hybridus were observed in Bloemfontein, South Africa. Examination of symptomatic stems revealed larval galleries of the pigweed weevil (Hypolixus haerens). The objectives of this study were to: identify the most common fungal species associated with this damage, determine if the adult pigweed weevil might be a vector for the fungi, and test if the associated fungi can cause the stem canker disease observed in the field. The most common fungal species isolated were Fusarium subglutinans from discolored tissues adjacent to insect galleries (42%), F. subglutinans from weevil larvae (29%), the Alternaria tenuissima group from adult weevils (31%), and the A. tenuissima group from cankered stems (40%). Three of the seven most common fungal species produced cankers following wounding and inoculation, with F. sambucinum and F. oxysporum being the most aggressive. Although fungal species compositions differed (P < 0.01) among the four tissue/insect stage combinations tested, all four had the same major fungal species, suggesting the pigweed weevil as a vector for the Fusarium pathogens. There is significant potential for yield loss affiliated with this insect-fungal association. The identification of this insect-fungal relationship and the pathogens involved in disease set the stage for further research on the etiology and disease management of this important insect-fungal relationship.
Sensitivity of Monilinia fructicola from Stone Fruit to Thiophanate-Methyl, Iprodione, and Tebuconazole
Authors: Yoshimura Michael A. , Luo Yong , Ma Zhonghua , Michailides Themis J.
Published: May 2007

Sensitivity in Monilinia fructicola to three fungicides was determined by measuring mycelial growth in fungicide-amended media. Resistance to thiophanate-methyl was found in 39 of 52 isolates (75%) collected from 1992 to 1998 (historic population) and 22 of 100 isolates (22%) collected in 2002 (current population). Three groups having distinct ranges of values for 50% effective concentration (EC50) to thiophanate-methyl were identified. Benzimidazole-sensitive (benS) isolates had EC50 values less than 2.0, low-resistant (benL) isolates between 2.0 and 30.0, and high-resistant (benH) isolates greater than 30.0 μg/ml. One (2%) isolate from the historic and three (3%) isolates from the current population were benH. Inoculation of untreated nectarine blossoms with four isolates from each of the three groups, individually or combined using equal numbers of conidia from each isolate, showed that the benS, benL, and benH isolates were equally pathogenic and competitive. Use of thiophanate-methyl at 300 μg a.i./ml (half dosage) and 600 μg a.i./ml (full dosage) effectively reduced the percentage of blighted blossoms caused by the benS group but not that caused by the benL and benH groups. The benH isolates caused significantly greater percentage of blighted blossoms than the benL isolates at both dosage levels. None of the tested isolates of M. fructicola were resistant to either iprodione or tebuconazole.
Detection, Isolation, and Pathogenicity of Colletotrichum spp. from Strawberry Petioles
Authors: Mertely J. C. , Legard D. E.
Published: May 2007

The herbicide paraquat is used to kill plant tissues and accelerate the growth of quiescent fungal colonists. In this study, freezing was investigated as an alternative to paraquat for the detection of latent infections of Colletotrichum spp. on strawberry petioles. Apparently healthy petioles from field-grown plants and inoculated petioles from greenhouse-grown plants were killed by freezing or exposure to 0.3% paraquat, and incubated in petri dish moist chambers. Previously frozen petioles were treated with 0.525 or 0.0525% sodium hypochlorite and Tween 20 at 18 µl/liter for selected intervals to test the effects of surface disinfestation on detection frequency. After 5 to 7 days of incubation, Colletotrichum acervuli developed much more frequently on freeze- and paraquat-treated petioles than on washed petioles which were not killed. Detection frequencies were similar for paraquat and some freeze treatments, but the latter were negatively affected by prolonged surface disinfestation. Using the petiole freeze method, Colletotrichum acutatum, C. gloeosporioides, and Glomerella cingulata (the teleomorph of C. gloeosporioides) were detected on symptomless petioles of field-grown plants. In addition, C. acutatum and C. dermatium were detected on apparently healthy transplants from northern nurseries. All of these fungi are reported pathogens of strawberry, but not all C. gloeosporioides isolates from frozen petioles were pathogenic in greenhouse bioassays. Freezing is a viable, nonhazardous alternative to paraquat for the detection of latent Colletotrichum infections on strawberry.
Tumorigenic Agrobacterium sp. Isolated from Weeping Fig in Spain
Authors: Penyalver R. , Sánchez J. J. , Petit A. , Salcedo C. I. , López M. M.
Published: May 2007

Agrobacterium-like colonies were recovered onto Roy-Sasser's medium from a young tumor (4 cm in diameter) on the stem of weeping fig (Ficus benjamina L.), 10 cm from the crown. The galled plant was collected in 1999 from a garden center in Valencia, Spain. After colony purification and tomato and weeping fig plant inoculations, one nonpathogenic and five Agrobacterium isolates that were tumorigenic in both plant species were characterized. On the basis of biovar classification tests, the nonpathogenic isolate was identified as belonging to biovar 1 of Agrobacterium (now called A. tumefaciens), whereas the tumorigenic isolates could not be assigned to any of the known Agrobacterium biovars. The isolates were positive for oxidase, growth in 2% NaCl, production of alkali from l-tartaric acid, and production of acid from mannitol-CaCO3 and negative for 3-ketolactose production, growth and pigmentation in ferric ammonium citrate, growth at 35°C, citrate utilization, acid production from sucrose and melezitose, and alkali production from malonic acid. Nopaline was the unique opine found in galls induced in weeping fig plants inoculated with the pathogenic isolates. Moreover, all isolates utilize the opine nopaline, but not octopine, manopine, agropine, chrysopine, cucumopine, or mikimopine. They were susceptible to agrocin 84 produced by strain K84. Heat-treated bacterial suspensions of these isolates yielded the expected amplification product using polymerase chain reaction (PCR) with the FGPtmr530/FGPtmr701′ primers pair from the tmr gene (3). Aerial gall disease was first reported on F. benjamina in Florida (1), and the isolated agrobacteria belongs to a new species named A. larrymoorei (2). Later, tumorigenic agrobacteria from weeping fig galls were isolated in Italy and the Netherlands (4). Our data suggest that the tumorigenic strains isolated in Spain differ greatly from those first described in the United States (1) on the basis of alkali production from l-tartaric acid, chrysopine detection on tumors, susceptibility to agrocin 84, and tmr amplification, but they might be similar to some of the Italian isolates (4). To our knowledge, this is the first report of isolation of tumorigenic Agrobacterium sp. from F. benjamina L. in Spain.

References: (1) H. Bouzar et al. Appl. Environ. Microbiol. 61:65, 1995. (2) H. Bouzar and J. B. Jones. Int. J. Syst. Evol. Microbiol. 51:1023. 2001. (3) X. Nesme et al. Pages 47–50 in: Endocytobiology IV. P. Nardon et al. eds. INRA, France, 1989. (4) A. Zoina et al. Plant Pathol. 50:620, 2001.
Sterility Mosaic Disease—the “Green Plague” of Pigeonpea: Advances in Understanding the Etiology, Transmission and Control of a Major Virus Disease
Authors: Jones A. Teifion , Kumar P. Lava , Saxena K. B. , Kulkarni N. K. , Muniyappa V. , Waliyar Farid
Published: May 2007

Pigeonpea (Cajanus cajan), is a grain legume that is a very important subsistence crop in marginal farming systems adopted by millions of smallholder farmers in the Indian subcontinent. It is grown for its seed for human consumption and for income generation by trading surpluses in local and commercial markets, but is widely used for diverse purposes, including as animal fodder and for soil conservation. Sterility mosaic (SMD) is the most damaging disease of pigeonpea endemic in the Indian subcontinent. It causes yield losses of >US$300 million per annum in India and Nepal alone. SMD-affected plants show severe stunting and mosaic symptoms on leaves, with complete or partial cessation of flowering. The SMD causal agent is spread by the arthropod mite vector Aceria cajani (Acari: Eriophyidae). Cultivating SMD-resistant genotypes is the most viable way to manage this serious disease of pigeonpea. Progress in developing broad-based SMD resistant material has been hindered by the lack of knowledge of the causal agent, the absence of diagnostic tools, and factors influencing host-plant resistance. After seven decades of research, vital breakthroughs made on the identification, detection, transmission, and epidemiology of the SMD causal agent, Pigeonpea sterility mosaic virus (PPSMV), are enabling the development of broad-based durable resistant pigeonpea cultivars. These breakthroughs will contribute greatly to sustainable pigeonpea production and enhance the income and livelihood of poor farmers in the semi-arid tropics of the Indian subcontinent.
Insensitivity to the Fungicide Fosetyl-Aluminum in California Isolates of the Lettuce Downy Mildew Pathogen, Bremia lactucae
Authors: Brown Sarah , Koike Steven T. , Ochoa Oswaldo E. , Laemmlen Frank , Michelmore Richard W.
Published: May 2007

Lettuce downy mildew, caused by Bremia lactucae, is the most important foliar disease of lettuce in California. In recent years, there were apparent failures of fungicides containing fosetyl-aluminum (Aliette) to control downy mildew in commercial lettuce fields in California. Consequently, we characterized 134 isolates collected over 2 years from throughout the coastal growing areas of California for insensitivity to the fungicides fosetyl-aluminum and maneb, pathotype, and mating type. Tests using seedlings in controlled growth room conditions demonstrated the widespread occurrence of insensitivity to fosetyl-aluminum in California populations of B. lactucae. Fifty percent of the isolates assayed sporulated profusely in the presence of fosetyl-aluminum applied at rates twice the normal field dosage, and an additional 40% showed moderate sporulation at this rate. Fosetyl-aluminum-insensitive isolates were detected from all regions sampled. Insensitivity was also observed in multiple pathotypes. Insensitivity was not complete, however, because quantitative analysis of the number of lesions on older plants revealed that applications of fosetyl-aluminum could reduce the levels of disease by 50%. Therefore, while fosetyl-aluminum may have utility under low disease pressure in the field, other control measures are required to provide control under conditions favorable to the disease.
Engineered Resistance Against Papaya ringspot virus in Venezuelan Transgenic Papayas
Authors: Fermin Gustavo , Inglessis Valentina , Garboza Cesar , Rangel Sairo , Dagert Manuel , Gonsalves Dennis
Published: May 2007

Local varieties of papaya grown in the Andean foothills of Mérida, Venezuela, were transformed independently with the coat protein (CP) gene from two different geographical Papaya ringspot virus (PRSV) isolates, designated VE and LA, via Agrobacterium tumefaciens. The CP genes of both PRSV isolates show 92 and 96% nucleotide and amino acid sequence similarity, respectively. Four PRSV-resistant R0 plants were intercrossed or selfed, and the progenies were tested for resistance against the homologous isolates VE and LA, and the heterologous isolates HA (Hawaii) and TH (Thailand) in greenhouse conditions. Resistance was affected by sequence similarity between the transgenes and the challenge viruses: resistance values were higher for plants challenged with the homologous isolates (92 to 100% similarity) than with the Hawaiian (94% similarity) and, lastly, Thailand isolates (88 to 89% similarity). Our results show that PRSV CP gene effectively protects local varieties of papaya against homologous and heterologous isolates of PRSV.
Inheritance of Resistance to Stagonospora nodorum Leaf Blotch in Kansas Winter Wheat Cultivars
Authors: Kim Yong-ki , Brown-Guedira Gina L. , Cox Thomas S. , Bockus William W.
Published: May 2007

Stagonospora nodorum blotch can cause serious yield and quality losses of wheat (Triticum aestivum) in many countries worldwide. Although there are other control methods, host resistance is the most desirable. Three recent Kansas winter wheat cultivars (Betty, Heyne, and 2163) have been developed with moderate levels of resistance to the leaf phase of Stagonospora nodorum blotch. To determine inheritance of resistance and allelism, these cultivars were crossed with one of three susceptible lines (Larned, KS96WGRC39, or Newton) and intercrossed in all possible combinations, including reciprocals. The parents, F1, F2, and F3 generations were tested for resistance to S. nodorum in the greenhouse as 4-week-old seedlings. Cytoplasmic effects were not detected in any cross. The mean levels of infection in the F1s of the two crosses Betty × Larned and Heyne × KS96WGRC39 indicated resistance was dominant. The observed phenotypic ratios of F2 plants for both crosses were not significantly different from the expected ratio for a single dominant gene. The ratio observed for F3 lines in the Betty × Larned cross fit that expected for a single dominant gene. However, the observed ratio of the F3 lines from the cross Heyne × KS96WGRC39 did not fit the ratio expected for a single dominant gene. The allelism test for Betty and Heyne indicated that they have different resistance genes. The F1 mean rating of the cross 2163 × Newton was intermediate between the two parents, indicating the absence of dominance for resistance in 2163. The phenotypic ratio observed in the F2 plants from this cross did not fit the ratio expected for a single dominant gene. The simple genetic control of resistance in cv. Betty makes it a useful source of resistance for wheat breeding programs.
Applying Rice Seed-Associated Antagonistic Bacteria to Manage Rice Sheath Blight in Developing Countries
Authors: Mew Twng Wah , Cottyn Bart , Pamplona Raymond , Barrios Helen , Xiangmin Li , Zhiyi Chen , Fan Lu , Nil-panit Nongrat , Arunyanart Parkpian , Van Kim Pham , Van Du Pham
Published: May 2007

One promising area of disease management for resource-poor farmers that emerged in recent years in developing countries is the potential of biological control. Biological control agents (BCAs) were found to be ubiquitous in the rice ecosystem. Seed bacterization with BCAs appeared to promote plant growth. BCAs showed efficacy on sheath blight (Rhizoctonia solani AG 1) but produced inconsistent results over time in the field using it alone. The control efficiency ranged from 50 to over 90%, with a high variance. To improve the efficacy, a half-dose of a commonly used fungicide, like Jingangmycin in China and Validamycin in Vietnam, was introduced to mix with BCAs and was found to be effective, and it reduced the variance of the field performance tests. To scale up the BCA technology for resource-poor farmers, a participatory approach, engaging the farmers to evaluate the product, was initiated in China and Vietnam. The BCA strain that is indigenous at a locality is mass produced at the research institution based on the total area required for application, as relayed by the farmers to extension workers. The demand by farmers would serve as the basis for the amount to be produced and for delivery to the rice farmers who were participating in the trials and, later, to those farmers who ordered the product. This process alleviates BCA storage and shelf-life problems. Data from the field performance trials also were used by the researchers to apply for registration for commercial use of BCAs. Scaling up to extend the BCA technology to more rice farmers as an integral part of their pest management scheme, in particular, and crop management practices, in general, is foreseen in the near future.
Crown and Root Infection of Lisianthus Caused by Fusarium solani in South Africa
Authors: Truter M. , Wehner F. C.
Published: May 2007

Cultivation of lisianthus (Eustoma grandiflorum (Raf.) Shinn.) is a minor industry in South Africa, with only a few growers producing the crop commercially. Commercial production at a location in Gauteng Province is hampered by rotting of the crowns and roots of plants that result in mortality of as much as 22% of the plants. At advanced stages of infection, the crowns of affected plants characteristically are covered with masses of fusoid, curved hyalophragmospores. Crowns and roots of symptomatic plants that were submitted by the grower in January 2003 were surface disinfested by immersing for 2 min in a 3% solution of sodium hypochlorite, and segments excised from the plant tissue were plated on potato dextrose agar supplemented with 50 mg l-1 of rifampicin. Fusarium solani (Mart.) Appel & Wollenw. (1), was consistently and exclusively isolated from the segments. Teleomorph Nectria haematococca Berk. & Broome, commonly developed in culture after incubation for 4 to 6 weeks, although no sexual structures were observed on infected plants. A spore suspension containing 104 micro- and macroconidia ml-1 was prepared for each of two single-conidial isolates of F. solani. Using a 0.8-mm-diameter hypodermic needle, 100 μl of each suspension was injected subepi-dermally into the crown of each of three 1-month-old disease-free lisian-thus plantlets (cv. Texas Blue Bell) growing in 500-ml plastic pots filled with sterilized vermiculite. In addition, each suspension was incorporated at 2% (vol/vol) into three pots with sterile vermiculite, and a plantlet was planted in each pot. Control plantlets were treated similarly, but with sterile distilled water. All inoculated plantlets developed crown rot and wilted within 2 weeks while maintained at 28°C in a greenhouse, regardless of mode of inoculation, and F. solani was readily reisolated from their crowns and roots. Control plantlets remained symptomless and did not yield F. solani. Crown and root infection of lisianthus by F. solani has been described (2,3), but to our knowledge, this is the first report of the disease in South Africa.

References: (1) P. E. Nelson et al. Fusarium species: An Illustrated Manual for Identification. Pennsylvania State University Press, University Park. 1983. (2) J. J. Taubenhaus and W. N. Ezekiel. Phytopathology 24:19, 1934. (3) S. Wolcan et al. Plant Dis. 85:443, 2001.
First Report of Bean yellow mosaic virus (Pea Mosaic Strain) in Verbena × hybrida
Authors: Guaragna M. A. , Jordan R. L. , Putnam M. L.
Published: May 2007

Verbena × hybrida is an ornamental annual used in rock gardens as an edging plant and hanging baskets. It comes in a variety of colors and grows approximately 1.5 to 2.5 cm (6 to 10 inches) high. In the spring of 2002, verbena cv. Lavender Shades plants from California showing leaf mosaic symptoms tested positive for potyvirus using an antigen-coated plate enzyme-linked immunosorbent assay with our genus Potyvirus broad spectrum reacting PTY-1 monoclonal as the detecting antibody (3). The virus was transmitted mechanically to Nicotiana benthamiana by sap inoculation from infected verbena plants. Infected tobacco showed systemic mild mosaic symptoms. Total RNA extractions from infected verbena and tobacco leaves were used in reverse transcription-polymerase chain reaction (RT-PCR) assays with generic potyvirus-specific primers that amplify highly conserved 700-bp or 1,600-bp fragments from the 3′ terminus of most potyviruses. This region includes the 3′ noncoding region (3′NCR) and the potyviral coat protein (CP). The PCR-amplified fragments were cloned by using standard TA cloning procedures and sequenced using dye-terminator chemistry. The cloned nucleotide and putative coat protein amino acid sequences from the infected verbena and tobacco plants were compared with the corresponding regions of other potyviruses. Amino acid comparison of the CP region of the verbena po-tyvirus showed 95 to 96% identity to four pea mosaic strains (PMV) of Bean yellow mosaic virus (BYMV), 85 to 89% identity to 20 other strains of BYMV, 74 to 76% identity with six strains of Clover yellow vein virus (CYVV), and only 50 to 64% identity with 28 other potyviruses. Pairwise comparisons among and between the CP sequences of PMV, BYMV, CYVV, and other potyviruses revealed identities of 92 to 99% for BYMV∷ BYMV, PMV∷PMV, and CYVV∷CYVV; 84 to 89% for BYMV∷ PMV, 69 to 78% for BYMV∷CYVV and PMV∷CYVV, and 50 to 64% for all other potyvirus combinations. Additionally, similar pairwise analysis of the 3′NCR of the verbena potyvirus revealed 98 to 99% identity to PMV strains, 81 to 94% to other BYMVs, 68 to 75% to CYVVs, and 52 to 64% with other potyviruses. Other 3′NCR pairwise comparisons generally revealed the same identity trend as described for the CP. Further serological analysis with our panel of BYMV-specific, BYMV-subgroup, and potyvirus cross-reactive monoclonal antibodies (3) confirmed the designation of the verbena potyvirus isolate as a pea mosaic strain of BYMV. To our knowledge this is the first confirmed report of BYMV-pea mosaic strain in Verbena (1,2).

References: (1) Agdia, Inc. Positive Ornamental Plant Samples. Agdia On-line Publication, 2003. (2) A. A. Brunt et al. Verbena hybrida. Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version 20. On-line publication, August 1996. (3) R. L. Jordan, and J. Hammond. J. Gen. Virol. 72:1531, 1991.
First Report of Strawberry latent ringspot virus in Strawberry in the United States and Canada
Authors: Martin R. R. , Tzanetakis I. E. , Barnes J. E. , Elmhirst J. F.
Published: May 2007

Strawberries in southern California have shown decline symptoms during the last 2 years. More than 70% of plants tested in California were infected with two newly identified criniviruses that infect strawberry (Strawberry pallidosis and Beet pseudo-yellows). Strawberry cultivars are usually symptomless when infected with one virus, and testing for other strawberry viruses is performed to identify any other viruses that may be involved in the symptomatology. Primers SLRSV F (5′ CCTCTCCAACC-TGCTAGACT 3′) and SLRSV R (5′ AAGCGCATGAAGGTGTAACT 3′) that amplify a 497-bp fragment of RNA 2 of Strawberry latent ringspot virus (SLRSV) were developed and utilized for reverse transcription-polymerase chain reaction (RT-PCR) detection. SLRSV belongs to the family Sequiviridae and is transmitted by nematodes of the genus Xiphinema. The virus has a broad host range (4) and is usually symptomless in strawberries. Strawberry plants from commercial fields in California, Oregon, Washington, and British Columbia, Canada were tested. SLRSV was identified in 17% of plants tested from California and 4% of plants tested from British Columbia, while all samples from Oregon and Washington tested negative. The fragment amplified (GenBank Accession No. AY461735, isolate from British Columbia, Canada) shares 84% nucleotide and 94% amino acid sequence identity with the previously published sequence of SLRSV from strawberry (GenBank Accession No. X77466) (3). The virus was transmitted mechanically from strawberry samples from Canada to Chenopodium quinoa, and the infected C. quinoa plants tested positive for SLRSV with RT-PCR, while no amplicons were obtained from noninoculated control plants. To our knowledge, this is the first report of SLRSV in strawberry in North America, although it has been previously reported in a single cherry tree in Ontario, Canada (1) and in an imported seed lot of parsley in California (2). The number of plants that tested positive as well as the geographic distribution of the virus indicates that the virus is widespread in California, but further testing is needed to identify its distribution in other states.

References: (1) W. R. Allen et al. Phytopathology 60:1262, 1970. (2) C. M. Hanson and R. N. Campbell. Plant Dis. Rep. 63:142, 1979. (3) S. Kreiah et al. J. Gen. Virol. 75:2527, 1994. (4) K. Schmelzer. Phytopath. Z. 66:1, 1969.
An Immunological System for the Detection of Pepper mild mottle virus in Soil from Green Pepper Fields
Authors: Ikegashira Y. , Ohki T. , Ichiki U. T. , Higashi T. , Hagiwara K. , Omura T. , Honda Y. , Tsuda S.
Published: May 2007

A reliable method, based on the double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), was developed for the extraction of viruses from soil and optimized for the detection of Pepper mild mottle virus (PMMoV) in soil taken from green pepper (Capsicum annuum) fields. When added to phosphate buffer, Tween 20 increases extraction efficiency and skim milk increases the specificity for PMMoV. Samples positive by DAS-ELISA were verified by inhibition testing using specific anti-PMMoV antibody, immuno-electron microscopy, reverse transcription-polymerase chain reaction, and inoculation tests on assay plants. Our system for detecting PMMoV in soil was successfully tested on samples from 22 infected and uninfected fields in Japan. When used before seedlings are planted, this method allows for the prediction of possible damage to cultivated plants by soil-borne PMMoV.
Transmission, In Planta Distribution, and Management of Hibiscus latent Fort Pierce virus, a Novel Tobamovirus Isolated from Florida Hibiscus
Authors: Kamenova Ivanka , Adkins Scott
Published: May 2007

Three aspects of the infection process of a new tobamovirus species, Hibiscus latent Fort Pierce virus, recently isolated from hibiscus in Florida, were examined: (i) transmission efficiency of rub-, slash-, and cut-inoculation for two hibiscus cultivars, Pink Versicolor and Brilliant Red; (ii) distribution within infected hibiscus plants; and (iii) treatments to prevent infection during plant propagation and pruning. Rub-, slash-, and cut-inoculation methods were all effective and yielded infection rates of 66, 74, and 70%, respectively, in Pink Versicolor and 50, 56, and 38%, respectively, in Brilliant Red. Analysis of virus distribution in infected plants over time revealed that the virus moved from the place of inoculation to the roots and then toward the bottom (oldest) leaves of the plants. Virus was found in all leaves on branches of Brilliant Red plants at 210 days postinoculation, whereas it remained restricted to the bottom and middle leaves of Pink Versicolor plants at 290 days postinoculation. Although several treatments of tools reduced infection of hibiscus during experiments mimicking plant propagation and pruning, 10% (wt/vol) sodium hypochlorite and 20% (wt/vol) nonfat dry milk completely prevented infection.
First Report of the Root-Knot Nematode Meloidogyne ethiopica on Tomato in Slovenia
Authors: Širca S. , Urek G. , Karssen G.
Published: May 2007

The root-knot nematode Meloidogyne ethiopica Whitehead originally described from Tanzania is also distributed in South Africa, Zimbabwe, and Ethiopia (3). Although this species is a relatively unknown root-knot nematode, M. ethiopica parasitizes several economical important crops, such as tomato, cowpea, bean, cabbage, pepper, pumpkin, tobacco, lettuce, and soybean (4). This species can be morphologically confused with M. incognita (Kofoid & White), and therefore, is probably easily overlooked (1). Recently, characteristic esterase isozyme patterns were described for this species, which provide a more reliable identification (2). In October 2003, Lycopersicum esculentum cv. Belle plants with large root-galls were observed in a greenhouse at Dornberk, Slovenia, which were identified as an unknown root-knot nematode within the M. incognita group. Subsequent sampling revealed infestation of all tomato plants within this greenhouse with obvious aboveground symptoms of stunting and wilting. Additional morphological and isozyme studies identified this root-knot nematode as M. ethiopica. The identification was based on female, male, and second-stage juvenile morphology and malate dehydrogenase and esterase isozyme phenotypes from young egg-laying females isolated from 20 tomato plants and compared with a culture of M. ethiopica from Africa. To our knowledge, this is not only the first report of M. ethiopica in Slovenia, but also the first report of this species in Europe.

References: (1) A. M. Golden. Fundam. Appl. Nematol. 15:189, 1992. (2) W. Mandefro and K. Dagne. Afr. J. Plant Prot. 10:39, 2000. (3) A. G. Whitehead. Trans. Zool. Soc. Lond. 31:263, 1968. (4) A. G. Whitehead. Nematologica 15:315, 1969.
First Report of Powdery Mildew Caused by Erysiphe aquilegiae var. aquilegiae on Aquilegia flabellata in Italy
Authors: Garibaldi A. , Bertetti D. , Gullino M. L.
Published: May 2007

Aquilegia flabellata Sieb. and Zucc. (columbine) is a perennial garden species belonging to the family Ranunculaceae. During the summer of 2003, a severe outbreak of a previously unknown powdery mildew was observed in several gardens near Biella (northern Italy). Upper surfaces of leaves were covered with a white mycelium and conidia, and as the disease progressed infected leaves turned yellow and died. Foot cell was cylindric and appressorium lobed. Conidia were hyaline, ellipsoid, and measured 31.2 to 47.5 × 14.4 to 33 μm (average 38.6 × 21.6 μm). Fibrosin bodies were not present. Cleistothecia were globose, brown, had simple appendages, ranged from 82 to 127 (average 105) μm in diameter, and contained one to two asci. Ascocarp appendages measured five to eight times the ascocarp diameter. Asci were cylindrical (ovoidal) and measured 45.3 to 58.2 × 30.4 to 40.2 μm. Ascospores (three to four per ascus) were ellipsoid or cylindrical and measured 28.3 to 31.0 × 14.0 to 15.0 μ;m. On the basis of its morphology, the pathogen was identified as Erysiphe aquilegiae var. aquilegiae (1). Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of five, healthy A. flabellata plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a garden where temperatures ranged between 20 and 30°C. After 10 days, typical powdery mildew symptoms developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of the presence of powdery mildew on Aquilegia flabellata in Italy. E. communis (Wallr.) Link and E. polygoni DC. were reported on several species of Aquilegia in the United States (2), while E. aquilegiae var. aquilegiae was previously observed on A. flabellata in Japan and the former Union of Soviet Socialist Republics (3). Specimens of this disease are available at the DIVAPRA Collection at the University of Torino.

References: (1) U. Braun. Nova Hedwigia, 89:700, 1987. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) K. Hirata. Host Range and Geographical Distribution of the Powdery Mildews. Faculty of Agriculture, Niigata University, 1966.
First Report of Powdery Mildew Caused by an Oidium sp. on Papaver nudicaule in Italy
Authors: Garibaldi A. , Minuto A. , Bertetti D. , Gullino M. L.
Published: May 2007

Iceland poppy (Papaver nudicaule L.) is grown on the Italian Riviera for export as a cut flower and its importance in the industry is increasing. During the spring of 2003, severe outbreaks of powdery mildew that had not been reported previously, occurred in several commercial plantings grown outdoors in containers near Imperia in northern Italy. Mycelium was observed on all green organs of the plant (leaves, stems, and petioles). Both surfaces on the leaves were affected, and heavily colonized leaves were distorted. As the disease progressed, diseased leaves turned yellow and died. The disease did not affect the flowers. Conidia were hyaline, cylindric, and measured 10.8 to 29.8 × 16.8 to 48.0 μm (average 13.7 × 37.3 μm). Foot cells were cylindric and appressoria unlobed. Fibrosin bodies were not present, and cleistothecia were not observed. The pathogen was identified as Oidium sp. subgenus Pseudoidium (1,2). Pathogenicity was confirmed by gently pressing leaves with visible sporulation onto the leaves of five 90-day-old P. nudicaule plants that were healthy and free of symptoms. Five noninoculated healthy plants served as controls. Inoculated and noninoculated plants were maintained in a growth chamber at 15°C with a 12-h photoperiod. After 7 to 10 days, typical symptoms of powdery mildew developed on inoculated plants but not on noninoculated plants. Previously, Erysiphe cruciferarum Opiz ex L. Junell has been reported on P. nudicaule in all continents, and E. cichoracearum DC. and E. polygoni DC. have been reported in several countries, including Italy, as a causal agent of powdery mildew on other species of Papaver including P. rhoeas and P. strigosum. To our knowledge, this is the first report of powdery mildew caused by an Oidium sp. on P. nudicaule in Italy. The voucher specimen is kept in the department collection at the University of Torino.

References: (1) R. Belanger et al., eds. The Powdery Mildew A Comprehensive Treatise. The American Phytopathological Society, St Paul, MN, 2002. (2) U. Braun. Nova Hedwigia. 89:700, 1987.