bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of Downy Mildew (Caused by Peronospora destructor) of Onion in Georgia
Authors: Langston D. B. , Sumner D. R. 
Published: May 2007

In February 1999, localized areas in a commercial field of Vidalia sweet onions in Toombs County, GA, exhibited symptoms that included elongated pale to light tan lesions on older leaves as well as some totally collapsed leaves. A dark, sooty to purple-gray fungal growth also was observed on affected leaves. Both symptoms and signs were observed during a period of wet, cool weather. Microscopic observation of affected tissues revealed nonseptate mycelia and dichotomously branched sporangiophores, which tapered to short sterigmata, giving rise to pyriform to fusiform sporangia. Based on these observations, the disease was determined to be downy mildew of onion caused by Peronospora destructor (Berk.). The dimensions of 25 sporangia averaged 25.1 ± 3.8 × 64.2 ± 4.3 μm, falling within the range of those currently reported for P. destructor (1). The disease was isolated to the field in which it was initially reported and did not cause extensive damage. Its failure to progress and spread may have been due to the warm, dry conditions that prevailed subsequent to symptom detection. This is the first report of P. destructor in Georgia. Reference: (1) H. F. Schwartz and S. K. Mohan. 1995. Diseases of aerial parts caused by fungi. Pages 20–24 in: Compendium of Onion and Garlic Diseases. The American Phytopathological Society, St. Paul, MN.
Bean Anthracnose: Virulence of Colletotrichum lindemuthianum Isolates from Burundi, Central Africa
Authors: Bigirimana J. , Fontaine R. , Höfte M. 
Published: May 2007

The diversity of Colletotrichum lindemuthianum is a major limiting factor in control of anthracnose on bean (Phaseolus vulgaris), and race characterization of this pathogen is an important tool in breeding programs. Race characterization has been carried out on isolates from North, Central, and South America; Europe; and Asia, but little or no information exists on the diversity of C. lindemuthianum in Africa. In this work, 12 isolates from the major bean-growing areas of Burundi, Central Africa, were characterized. Their virulence was tested on 12 bean differential cultivars (1) and on 4 bean cultivars commonly grown in Burundi: 2 from local germ plasm (Muyinga-1 and Urubonobono) and 2 from Colombia (A 321 and Calima). Detached unifoliate bean leaves from 8-day-old plants were placed on a humid surface in trays and sprayed until runoff with a suspension of 106 spores ml-1. Trays covered with transparent plastic sheets to keep a minimum relative humidity of 92% were incubated at 20°C. Seven days after inoculation, symptoms were evaluated for severity on a scale of 1 to 9. Leaves scored as 1 to 3 were considered resistant. Races were characterized according to a numerical binary system (1). Nine races were identified: 9, 69, 87, 384, 385, 401, 448, 449, and 485. Seven of these races (9, 69, 87, 384, 401, 448, and 485) were described for the first time in Africa. Races 401 and 485 have not yet been reported in the literature. The most susceptible differential cultivars were Michelite, PI 207262, To, and Mexico 222. Muyinga-1, Urubonobono, and A 321 were sensitive to nine, six, and five races, respectively. There is a high diversity of C. lindemuthianum in Burundi, and the local germ plasm tested is very susceptible to the characterized races. Breeding programs in Burundi should focus on lines and cultivars, such as Tu, AB 136, G 2333, and Calima, that are resistant to all the races characterized in this study. Reference: (1) M. A. Pastor-Corrales. Phytopathology 81:694, 1991.
Identification of Tomato yellow leaf curl virus-Is in The Bahamas
Authors: Sinisterra X. , Patte C. P. , Siewnath S. , Polston J. E. 
Published: May 2007

In December 1996, symptoms of stunting, curling, and marginal chlorosis of leaves, reduced leaf size, and marked reduction in number of fruits were first seen in tomato (Lycopersicon esculentum) plants on the island of North Andros, The Bahamas. Similar symptoms were observed for the first time during fall 1997 in tomatoes on the island of Eleuthera. Incidences of symptomatic plants were as high as 100% in some fields. Leaves from one symptomatic plant from each island were collected during April 1998. DNA was extracted from the samples and tested by polymerase chain reaction (PCR) amplification for the presence of one or more geminiviruses (2). Three sets of primers were used to amplify the extracts: PAL1c496 and PAL1v1978, which amplify an ≈1,100- or ≈1,300-bp DNA product from the A component of a wide range of bipartite and monopartite begomoviruses, respectively; primers PCRc154 and PBL1v2042, which amplify an ≈600-bp DNA fragment from the B component of a wide range of bipartite geminiviruses; and primers PCRc154 and PTYC1v2180 (5′ACTACCATGGCCGC-GCAGCGGAATAC3′), which preferentially amplify Tomato yellow leaf curl virus (TYLCV-Is) (1,2). DNA products of ≈1,300 and ≈780 bp were amplified with PAR1c496 and PAL1v1978 and PCRc154 and PTYC1v2180, respectively, from one sample from each island. No product was obtained from primers PCRc154 and PBL1v2042. The symptoms and PCR results are consistent for the presence of TYLCV. PCR products generated by primers PAL1c496 and PAL1v1978 from each sample were cloned into a pGEM-T Easy Vector (Promega, Madison, WI), and one clone from each was sequenced with vector primers. The sequences of the two 1,300-nt Bahamian clones were identical. The Bahamian clones shared 98.9% sequence homology with equivalent sequences of a TYLCV-Is clone from Florida, 99.2 and 99.4% homology with two TYLCV-Is clones from the Dominican Republic (GenBank Accession no. AF024715, and a full-length infectious clone submitted to GenBank), 98.7% homology with a clone from Cuba (GenBank Accession no. AJ223505), and 98.0% homology with the type sequence from Israel (GenBank Accession no. X15656). A deletion (28 or 29 nt) in the intergenic region was shared by clones from The Bahamas and Florida but was not present in clones from Cuba (AJ223505), the Dominican Republic (AF024715), Egypt (GenBank Accession no. L12219), Israel (X15656), Jamaica (GenBank Accession no. U84146), Lebanon (GenBank Accession no. AF160875), Mexico (GenBank Accession no. AF168709), and Spain (GenBank Accession no. AJ223505). TYLCV-Is appeared in The Bahamas and Florida at almost the same time (1). Because clones from both locations share an unusual deletion, there may be a common source for both introductions. This is the first report of TYLCV-Is in The Bahamas. Reference: (1) J. E. Polston et al. Plant Dis. 83:984, 1999. (2) M. R. Rojas et al. Plant Dis. 77:340, 1993.
First Report of Aphanomyces Root Rot of Sugar Beet in Nebraska and Wyoming
Authors: Harveson R. M. 
Published: May 2007

Sugar beet (Beta vulgaris L.) plants exhibiting dull green and chlorotic foliage were first observed in a field near Dalton, NE, in late July 1999. Root symptoms included distal tip rot with internal, yellow-brown, water-soaked tissues. Isolations on MBV medium (1) consistently yielded Aphanomyces cochlioides Drechs. Water cultures produced primary zoospores that encysted at the tips of sporangiophores, followed by release of secondary zoospores within 12 h. Seedlings inoculated with zoospores began to die 2 weeks after emergence in a greenhouse. Symptoms on hypocotyls began as water-soaked lesions that turned black and thread-like. The causal agent was reisolated from infected seedlings, completing Koch's postulates. The disease was subsequently found in more than 15 separate fields, representing 5 of 11 sugar beet-growing counties in Nebraska and 1 county in Wyoming. In October, plants from the same fields were observed with stunted, distorted roots and superficial, scabby lesions associated with latent A. cochlioides infection. The pathogen could not be isolated from this stage but was confirmed by observing mature oospores within thin, stained sections under a microscope. The sections were additionally mixed with sterile potting soil and planted in the greenhouse with sugar beets. Several weeks after emergence, seedlings began to die, and the pathogen was reisolated. This represents the first report of Aphanomyces root rot and its spread in the Central High Plains. It also confirms that the described latent symptoms on sugar beet are caused by A. cochlioides. Reference: (1). W. F. Pfender et al. Plant Dis. 68:845, 1984.
First Report of Powdery Mildew on Nandina domestica (Berberidaceae) in North America
Authors: Saenz G. S. , Koike S. T. , Scheck H. J. 
Published: May 2007

Nandina domestica Thunb. (heavenly bamboo) is an ornamental plant that is widely planted in landscapes in California and other states. Since 1996, powdery mildew disease has been seen on outdoor landscape N. domestica in various regions of California (Alameda, Monterey, Riverside, and Santa Barbara counties). Symptoms consist of reddening of leaf and stem tissues colonized by the fungus and curling and twisting of infected leaves. The following observations were the same for all collected isolates. White ectophytic mycelium was observed on leaves and petioles. Mycelium on leaves was amphigenous, mostly epiphyllous, and effused or in patches. Hyphal appressoria were nipple-shaped to lobed and sometimes opposite in orientation. Conidiophores were cylindrical, straight, sometimes slightly flexuous, 22 to 32 × 6 to 8 μm in dimension, and followed by one to two shorter cells. Conidia were cylindrical, produced singly, and 27 to 42 × 11.5 to 14 μm in dimension. Fibrosin bodies were not observed. Conidial germ tubes were approximately twice the length of the spore, originated from the ends of the spore, and terminated in simple appressoria. Cleistothecia were not present. Based on these characteristics, the fungus was identified as Microsphaera berberidis (DC) Lév. (1). Pathogenicity was confirmed by gently pressing diseased leaves on leaves of healthy N. domestica plants. Plants were incubated in a humidity chamber at 22 to 24°C, and after 10 to 14 days, powdery mildew colonies developed. A voucher specimen was deposited in the University of California Herbarium (UC 1738622). Additional inoculation experiments showed that four other N. domestica cultivars were susceptible (Compacta Nana, Gulf Stream, Harbour Dwarf, and Royal Princess). Helfer (2) noted several possible candidates for the Nandina powdery mildew pathogen in the United Kingdom. However, due to the conidial characteristics of that fungus and the paucity of character descriptions for the several species mentioned, no species name was given to the Edinburgh isolate. In contrast, the mitosporic characteristics of our isolates fit the description for M. berberidis. This is the first report of powdery mildew on N. domestica in North America. References: (1) U. Braun. Nova Hedwigia 89:1, 1987. (2) S. Helfer. Plant Dis. 79:424, 1995.
First Report of Verticillium dahliae Causing Wilt on Solanum cardiophyllum and Solanum ehrenbergii
Authors: Rodríguez-Alvarado G. , Fernández-Pavía S. P. , Galindo-Alonso J. 
Published: May 2007

Solanum cardiophyllum Lindl and Solanum ehrenbergii (Bitt) Rydb are wild edible potato plants found throughout central Mexico (2). These plants are not cultivated, but farmers collect tubers for their own consumption and to sell at local markets (2). Wilted plants were observed in experimental plots of these wild potatoes established near Chapingo, Mexico, during spring 1983. Initial symptoms included wilting and dark yellowing of lower leaves. As the disease advanced, all of the foliage became chlorotic and the plants wilted and eventually died. Disease incidence was 13.4% for S. ehrenbergii and 0.2% for S. cardiophyllum. Verticillium dahliae Kleb. was consistently isolated from the roots and lower stems of diseased plants of both Solanum species. The isolating procedure consisted of thoroughly rinsing roots and lower stems with tap water and cutting roots and stems into 3- to 6-cm sections that were placed in 10% bleach for 3 to 5 min. Bleach excess was removed with sterile paper, and the tissue sections were cut into smaller pieces (0.5 cm) and placed on potato dextrose agar (PDA) plates. Cultures of Verticillium produced numerous dark microsclerotia of various shapes and sizes (0.05 to 0.1 mm); erect, slender, hyaline, and branched conidiophores; and elliptical and hyaline, single-celled conidia characteristic of V. dahliae (1). Pathogenicity studies were conducted in a greenhouse on 2-month-old S. cardiophyllum and S. ehrenbergii plants grown from tubers. Inoculum was obtained from colonies growing on PDA for 10 days producing abundant conidia. Conidial suspensions were obtained by flooding the plate cultures with sterile distilled water, filtering the suspension with two layers of cheesecloth, and adjusting the inoculum to 1.0 × 106 conidia/ml (3). Ten ml of the conidial suspension were applied to each of four holes 5 cm deep and 3 to 5 cm next to the crown of each plant. Symptoms similar to those observed on field-grown plants were observed 15 days after inoculation, and V. dahliae was re-isolated from lower stems and roots. All inoculated plants were dead 4 weeks after inoculation. Water-inoculated plants remained healthy throughout the experiments. This is the first report of V. dahliae on S. cardiophyllum and S. ehrenbergii. References: (1) G. R. Dixon. Vegetable Crop Diseases. Avi Publishing, Westport, Connecticut. 1981. (2) J. Galindo. Naturaleza 13:175, 1982. (3) H. A. Melouk and C. E. Horner. Phytopathology 65:767, 1975.
First Report of Virulence in Argentine Populations of Puccinia sorghi to Rp Resistance Genes in Corn
Authors: Gonzalez M. 
Published: May 2007

Common rust (Puccinia sorghi) is a chronic disease of corn (Zea mays L.) in Argentina. Factors contributing to the disease include relatively susceptible germ plasm, planting late in the season, and variability within populations of P. sorghi. Several genes for race-specific resistance to common rust (i.e., Rp genes) were identified based on virulence in populations of P. sorghi in the United States (1). The objective of this research was to examine the virulence of Argentine populations of P. sorghi against 24 alleles at four Rp loci that condition race-specific resistance to common rust. Rp genes in an R168-inbred background were planted in trials at two locations in the central corn belt of Argentina. In the 1996-97, 1997-98, and 1999-2000 seasons, trials were planted in Pergamino (Province of Buenos Aires). In the 1998-99 season, the trial was planted in Zavalla (Province of Santa Fe). Plants were exposed to naturally occurring local populations of P. sorghi. About 3 to 4 weeks after anthesis, rust severity (percentage of leaf tissue with uredinia) and infection type were rated for all plants. Four categories of infection type were: 1—no rust, necrotic or chlorotic flecks, 2—small uredinia with or without necrotic flecks, 3—large uredinia, and 4—large uredinia with banding. Three lines with Rp genes (Rp1-N, Rp3-A, and Rp3-C) had infection type 1 with necrotic flecks and severity of 0%. Lines with other Rp genes (Rp1-A, Rp1-B, Rp1-C, Rp1-D, Rp1-E, Rp1-F, Rp1-G, Rp1-H, Rp1-I, Rp1-J, Rp1-K, Rp1-M, Rp1-N, Rp3-A, Rp3-B, Rp3-C, Rp3-D, Rp3-E, Rp4-A, Rp4-B, and Rp5) had infection types 2 to 4 and severity ranged from 5 to 35%. Severity was affected by the virulence of the populations and the environmental conditions in each trial. These results are evidence of a wide spectrum of virulence in P. sorghi populations in Argentina. Reference: (1) W. Hagan and A. Hooker. Phytopathology 55:193, 1965.
First Report of Alternaria Brown Spot of Citrus in Spain
Authors: Vicent A. , Armengol J. , Sales R. , García-Jiménez J. , Alfaro-Lassala F. 
Published: May 2007

In 1998, a new disease of Fortune mandarin trees was detected in orchards in the eastern province of Valencia. This is one of the most important late-maturing cultivars grown in Spain. Symptoms were typical of Alternaria brown spot of citrus (2). Young leaves showed brown necrotic and irregular blighted areas with characteristic yellow halos. The necrosis had a tendency to follow the veins. On fruits, symptoms included light brown, slightly depressed spots to circular and dark brown areas on the external surface. Infected young fruits and leaves often fell and the mature fruits were unmarketable due to lesions, resulting in important economic losses. Isolations on potato dextrose agar supplemented with 0.5 mg/ml of streptomycin sulfate (PDAS) from affected leaves and fruits consistently yielded Alternaria alternata (Fr.:Fr.) Keissl., which was identified based on conidial morphological characteristics. Pathogenicity tests were conducted using 15 isolates from fruit and leaves by inoculating detached immature Fortune leaves with a sterile water suspension of 5 × 105 conidia per ml. Drops of this suspension (40 μl each) were placed on the lower surfaces of each leaflet using four leaves per isolate. Leaves were incubated in a moist chamber in the dark at 27°C (1). After 48 h, most of these isolates caused necrotic lesions on the leaves similar to those observed in the field, and the fungus was reisolated, confirming Koch's postulates. In 1999, the fungus spread to other citrus-growing areas, and to date the disease has been detected affecting Fortune and Nova mandarins and Minneola tangelo. This is the first report of Alternaria brown spot of citrus in Spain. References: (1) K. Kohmoto et al. Phytopathology 81:719, 1991. (2) J. O. Whiteside. Plant Dis. Rep. 60:326, 1976.
First Report of Heterobasidion annosum on the Endemic Abies hickeli of Southern Mexico
Authors: Garbelotto M. , Chapela I. 
Published: May 2007

The basidiomycete Heterobasidion annosum (Fr.:Fr.) Bref. is a pathogen of conifers in the Northern Hemisphere. This fungus has been previously reported from Pinus spp. (1) and from Abies religiosa (H.B.K.) Schl. et Cham. (2) in Central Mexico. In 1998, H. annosum was collected for the first time from stumps of Abies hickeli Flous et Gaussen in the Southern Mexican State of Oaxaca, at an altitude of 2,900 m (Lat 17° 28′ N, Long 96° 31′ W). Although standing trees at the sampled site were asymptomatic, the sapwood and heartwood of several fir stumps were extensively decayed. The white laminated rot was similar to that caused by H. annosum on other Abies spp. Decay pockets extended to the upper surface of the stumps, indicating the fungus had infected and colonized the tree butts prior to tree felling. H. annosum basidiocarps were found both outside the roots in the duff layer and inside the decay pockets. The anamorph of H. annosum (Spiniger meineckellum (A. Olson) Stalpers) was isolated from the context of three basidiocarps. Based on comparative analysis of DNA sequences of the nuclear ribosomal internal transcribed spacer region, all three isolates belonged to the North American S intersterility group (ISG). This report expands the host and the geographic ranges of the North American S ISG, and represents the world's southernmost finding of an Abies species infected by this pathogen. References: (1) R. Martinez Barrera and R. Sanchez Ramirez. Ciencia Forestal 5(26):3, 1980. (2) M. Ruiz-Rodriguez and L. M. Pinzon-Picaseno. Bol. Soc. Bot. Mexico 54:225, 1994.
Stem Smut (Ustilago hypodytes) on Intermediate Wheatgrass in Canada
Authors: Chang K. F. , Howard R. J. , Gossen B. D. , Hwang S. F. 
Published: May 2007

Intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth & D.R. Dewey) (syn. Agropyron intermedium [Host] Beauv.) is becoming an important forage grass species in Alberta, Canada. Severe losses in seed yield due to stem smut (Ustilago hypodytes [Schlecht.] Fr.) were noted in a 70-acre field near Warner, AB, in 1999. The crop had been established in 1993 and harvested for seed each year. Smut symptoms (5% incidence) were noted initially in 1997. Incidence, determined by counting the number of symptomatic stems, increased to 10% in 1998 and 50% in 1999. The symptoms usually appeared in the first week of June. Brown sori developed on infected stems, especially between the uppermost node and the leaf below the flag leaf, and gradually became black during the period of seed filling, which is characteristic of stem smut (1). Teliospores were smooth, spherical to oval, light to dark brown, and 4.5 to 5.0 × 5.0 to 6.8 μm in dimension, which is also consistent with previous descriptions of U. hypodytes. Infected stems occasionally flowered, but did not set seed, so seed yield losses were proportional to disease incidence. Plants infected with stem smut were often stunted. Tissues in the smutty stem often became sunken and stems became twisted and thinner than normal due to the propagation of sori in the stem over time. Stem smut has been reported on crested wheatgrass and slender wheatgrass in other parts of Canada (2) and on T. intermedium in the United States (3). This is the first report of stem smut affecting commercial grass seed production in Alberta, Canada. This disease could also have a significant impact on the seed production of intermediate wheatgrass elsewhere. References: (1) G. W. Fischer. 1953. Manual of the North American Smut Fungi. Ronald Press, New York. (2) B. D. Gossen and D. Regnier. Can. Plant Dis. Surv. 71:88–89, 1991. (3) J. F. Karn and J. M. Krupinsky. Phytopathology 73:1152–1155, 1983.
First Report of Plum Pox Potyvirus in Ontario, Canada
Authors: Thompson D. , McCann M. , MacLeod M. , Lye D. , Green M. , James D. 
Published: May 2007

Plum pox potyvirus (PPV) causes plum pox (sharka) disease, which is considered the most serious disease of stone fruits including peach, plum, nectarine, and apricot (2). The disease may cause losses as high as 80 to 100% of some crops (2). A survey was initiated in the Niagara region of Ontario, Canada, after it was reported that PPV was detected in Pennsylvania (1). The initial survey focused on Prunus material imported into Canada from the Pennsylvania region. Where imported trees could be identified, every tree was sampled. In cases where the imported trees were growing in mixed blocks with plants from other sources, 25% of the trees were sampled and tested as composites of four trees. PPV was detected in three symptomless Fantasia nectarine (Prunus persica var. nectarina) trees by triple-antibody sandwich (TAS) ELISA using the REAL Durviz kit (Valencia, Spain), which contains the universal PPV monoclonal 5B. PPV infection was confirmed by western blot analyses (a PPV polyclonal antibody and PPV 5B monoclonal were used as primary antibodies), reverse transcription polymerase chain reaction (RT-PCR), and TC/RT-PCR. In western blot analyses, the coat protein subunit sizes of the Canadian PPV isolates were estimated at 32 kDa based on electrophoretic mobility in 12% SDS-PAGE. RFLP analysis of the 243-bp fragment amplified using PPV specific primers P1 and P2 (4) indicated the presence of RsaI and AluI enzyme restriction sites, which is characteristic of PPV D strains. In RT-PCR analysis using D and M specific primers (3), only the D specific primers amplified a fragment 198 bp in size. This data provided conclusive evidence that the PPV isolates detected in Canada were PPV D, similar to the strain detected in Pennsylvania. The survey is continuing and is being expanded to determine the extent of spread and the exact distribution of the virus. References: (1) L. Levy et al. Phytopathology (Abstr.) 90:46, 2000. (2) M. Nemeth. Virus, Mycoplasma, and Rickettsia Diseases of Fruit Trees. Akademiai Kiado, Budapest. (3) A. Olmos et al. J. Virol. Methods 68:127–137, 1997. (4) T. Wetzel et al. J. Virol. Methods 33:355–365, 1991.