bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of Peach latent mosaic viroid and Hop stunt viroid Infecting Peach Trees in the Czech Republic
Authors: Hassan M. , Rysanek P. , Di Serio F. 
Published: May 2007

Peach latent mosaic viroid (PLMVd) and Hop stunt viroid (HSVd) are known to naturally infect stone fruits, but their contemporary presence in peach trees has been reported only recently (3). During a field validation of detection methods developed for sanitary screening of propagation material, PLMVd and HSVd, alone or in mixed infections, were detected in peach trees grown in the trial orchard of the Czech University of Agriculture in Prague. Leaf samples were collected in September 2002 from symptomless trees of peach cultivars imported from the United States (cvs. Sunhaven, Redhaven, Fairhaven, Cresthaven, Dixired, Halehaven, and NJC 103), Slovakia (cv. Luna), and a tree of Chinese wild peach, Prunus davidiana, and analyzed by reverse transcription-polymerase chain reaction (RT-PCR). PLMVd cDNA was amplified as previously reported (2) or by using two sets of primer pairs designed to amplify partial cDNAs, one reverse primer R: GTTTCTACGG CGGTACCTGA, complementary to the nucleotide positions 204 to 223 and forward primers F1: CGTATCTCAACGCCTCATCA, homologous to the positions 109 to 128, and F2: CTGCAGTTCCCGCTAGAAAG, homologous to the positions 15 to 34 of PLMVd reference sequence (2). The two pairs using the R sequence produced the expected size PCR products of 115 and 209 bp, respectively. RT-PCR for HSVd detection was performed as reported (1). The same total RNA preparations were also analyzed by molecular hybridization with nonisotopic riboprobes specific for each viroid. With minor exceptions, both methods gave similar results. Of 66 tested trees, 5 were infected with PLMVd, 46 were infected with PLMVd and HSVd, and 15 were free of both viroids. Viroid free plants included cvs. Luna, Cresthaven, Dixired, and Halehaven and the species P. davidiana. The high number of infections by both viroids was unexpected because mixed infections are generally rare (3). Most likely, mixed infections occurred during field manipulations and propagation of infected materials. To our knowledge, this is the first report of PLMVd in the Czech Republic. Although further investigations are needed to ascertain the spread of stone fruit viroids in the Czech Republic, our results also report an unusually high incidence of mixed infections of peach trees in this country. These results stress the need for a certification program to help control the spread of stone fruit viroids in the Czech Republic. References: (1) K. Amari et al. J. Gen. Virol. 82:953, 2001. (2) A. M. Shamloul et al. Acta Hort. 386:522, 1995. (3) M. Tessitori et al. Plant Dis. 86:329, 2001.
First Report of White Leaf Spot of Dry Bean Caused by Pseudocercosporella albida in North America
Authors: Río L. E. del , Bradley C. A. , Lamppa R. S. 
Published: May 2007

In August 2002, white leaf spot disease was observed on red kidney bean (Phaseolus vulgaris L.) at three fields near Staples, MN. Disease incidence in these fields, calculated as the proportion of plants showing visible symptoms, ranged from 20 to 100%. Symptoms and signs consisted of abundant, white sporulation on the abaxial side of leaves that was limited by secondary veins, resulting in angular-shaped lesions. Corresponding with fungal growth, yellow, angular spots were observed on the upper leaf surface. In older leaves, lesions coalesced, covering most of their surface, while younger leaves were relatively free of symptoms. Heavily diseased plants senesced faster and defoliated earlier than nonsymptomatic plants. Identification of the pathogen was conducted by direct observation of infected plant tissues with light and electron microscopes. Conidia were hyaline, filiform, rounded at their apex, and with no visible scar at their point of attachment to the conidiophore. Conidia had one to four septa, were 57 to 68 μm long, and approximately 2.4 μm in diameter. Conidia were produced at the tip of colorless, short conidiophores that emerged through stomata in groups of five or more. These traits are in agreement with the description of Pseudocercosporella albida (Matta & Belliard) Deighton (1,2). A sample of infected tissues has been deposited at the U.S. National Fungus Collection (BPI 842303) at Beltsville, MD. The impact of this disease on bean yields in Minnesota was not estimated. However, in the cool highlands of Colombia, where white leaf spot is endemic, yields can be reduced by as much as 47% (3). To our knowledge, this is the first report of the presence of this pathogen on dry bean in North America. References: (1) F. C. Deighton. Trans. Br. Mycol. Soc. 66:547, 1976. (2) A. Matta and L. Belliard. Phytopathol. Mediterr. 12:102, 1973. (3) H. F. Schwartz et al. Plant Dis. 65:494, 1981.
The Perfect Stage of Powdery Mildew of Sugar Beets Found in Idaho and Colorado
Authors: Gallian J. J. , Hanson L. E. 
Published: May 2007

Powdery mildew (Erysiphe polygoni DC [synonym E. betae {Vanha} Weltzien]) of sugar beet (Beta vulgaris L.) has been a significant problem in many sugar beet growing areas of the United States since the first serious epidemic in 1974. Disease has been attributed solely to the asexual stage of the pathogen in the United States, except for one report of the perfect stage in a single field in Washington coincidental with the 1974 epidemic (1). In August 2001, ascomata were observed in several fields in Owyhee County in southwestern Idaho near Grand View. The perfect stage was widespread and easily found, and in one field the surfaces of leaves collected from 50 randomly sampled plants were between 10 and 90% covered with ascomata. Subsequently, the ascigerous stage was found in September and October in multiple fields in three additional counties in southwestern and south-central Idaho and two counties in northern Colorado. Ascomata were found on 12 commercial varieties in the two states and six breeding lines in Colorado. Asci contained one to four hyaline or yellow-to-golden pigmented ascospores per ascus. Ascomata observed in Idaho and Colorado are similar to those described from Europe (2). Ascospores appeared intact after leaves were dried and stored at 4 to 7°C more than 4 weeks. However, after leaves with ascomata were dried and stored at 24 to 27°C for 1 week or more, ascomata and asci appeared intact microscopically, but ascospores were no longer delineated and appeared desiccated or degraded. Because the ascigerous stage provides a means of genetic recombination, there is the potential for races of the pathogen to arise with greater frequency. This has serious implications for managing fungicide resistance and breeding for disease resistance to sugar beet powdery mildew. References: (1) D. L. Coyier et al. (Abstr.) Proc. Am. Phytopathol. Soc. 2:112, 1975. (2) S. Francis. Mol. Plant Pathol. 3:119, 2002.
Quercus canariensis, a New Host of Trabutia quercina
Authors: Trapero A. , Sánchez M. E. 
Published: May 2007

Quercus canariensis Willd. is an oak species endemic to northwestern Africa and the Iberian Peninsula. This species is particularly abundant in the southwestern Andalucía Region of southern Spain. During a disease survey in this area from 1997 to 1998, we observed Q. canariensis trees affected by a tar spot disease. Tar spot lesions were clearly differentiated by a black, crustose, and shiny stromata (10 to 20 mm in diameter) on the upper surface of leaves mainly arranged along leaf veins but also scattered randomly over the leaf surface. On most leaves there was little necrosis, and on most trees the damage was not serious, although some trees located in the most humid areas were severely affected with leaf chlorosis and heavy defoliation. Other Quercus species in the area, such as Q. ilex and Q. suber, did not show signs of tar spot. One fungus species was consistently associated with tar spots. The fungus formed ascomata, 250 to 400 µm in diameter, embedded in the stromata. Asci were clavate or saccate, 45 to 55 × 17 to 22 µm, eight spored, and short stalked. The ascus apex was acute to obtuse. Ascospores were arranged irregularly, 20 to 25 (-30) × 5 to 8.5 µm, fusiform to ellipsoidal fusiform, often curved and flattened on one side, thin walled, hyaline, aseptate, and smooth without a gelatinous sheath or appendage. Based on these characteristics, the fungus was identified as Trabutia quercina (Rudolphi ex Fr.) Sacc. & Roum., a pathogen causing tar spot in several Quercus species in the Northern Hemisphere (1). Samples were deposited in the Plant Pathology Mycotheca at the University of Córdoba, Spain (MIC-888 to MIC-897). To our knowledge, this is the first report of T. quercina on Q. canariensis and the first report of this pathogen in Spain. Reference: (1) P. F. Cannon. Mycopathologia 135:69, 1996.
First Report of Fusarium denticulatum from Sweet Potato in Venezuela
Authors: González M. S. , Fuenmayor F. , Godoy F. , Navas R. 
Published: May 2007

During 2001and 2002, 53 accessions of sweet potato (Ipomoea batatas L.) from a germ plasm collection maintained in the field at Centro Nacional de Investigaciones Agropecuarias, Maracay, Venezuela, were evaluated for diseases. Sweet potato accessions Catemaco and 2878 were symptomatic for chlorotic leaf distortion with deformation of young leaves and stunted vines. Symptomatic nodes and shoot tips were excised, surface disinfested in 0.5% sodium hypochlorite, cultured on potato dextrose agar (PDA), and incubated at 28°C. Pale pink colonies with white aerial mycelium developed from symptomatic tissues. At 20°C, pure cultures on PDA developed slow-growing, aerial, white-to-pink mycelium. Pigmentation in reverse was light orange. Conidia aggregated in false heads, and orange sporodochia were abundant. Conidiophores in aerial mycelium were prostrate, short, and sometimes branched. Sporodochial conidiophores were branched. Phialides were mostly monophialidic but occasionally polyphialidic and averaged 25.0 × 3.0 µm. Microconidia were abundant, long, oval to allantoid, and 0 to 1 septate. Macroconidia were fusiform to falcate with a beaked apical cell and a footlike basal cell, 3 to 5 sepate, and 38 to 45 × 3.6 to 4.0 µm. Chlamydospores were absent. The fungus was identified as Fusarium denticulatum Nirenberg and O'Donnell (1). Ten 25-cm-long vine-tip cuttings of accessions Catemaco and 2878 were immersed in a conidial suspension (1 × 106 conidia per ml) of F. denticulatum. As a control, vines were immersed in sterile, distilled water. After inoculation, each cutting was planted in a 13-cm plastic pot containing a soil/sand (1:1) mixture. Inoculated plants were covered with plastic bags for 48 h and grown in a greenhouse at temperatures ranging from 30 to 38°C. After 3 months, three inoculated plants of accession Catemaco and two plants of accession 2878 developed purple terminals and moderate interveinal chlorosis. Leaf distortion was not observed. F. denticulatum was recovered from both symptomatic and asymptomatic inoculated plants. To our knowledge, this is the first report of F. denticulatum from sweet potato germ plasm in Venezuela. Dried, pure cultures and slides of the fungus are being deposited in the Albert S. Muller Herbario Micologico (VIA). Reference: (1) H. I. Nirenberg and K. O'Donnell. Mycologia 90:434, 1998.
First Report of Sclerotium rolfsii on Brassidium Hybrid Orchid
Authors: Pratt T. B. , McMillan R. T. , Graves W. R. 
Published: May 2007

Brassidium hybrid orchid leaves were sent to the University of Florida Plant Disease Clinic in the summer of 2002. Symptoms on leaves were a spreading, cottony, white mass of mycelium with necrotic centers 3 to 5 × 5 to 9 mm. Approximately 1% of leaves submitted were affected. Sclerotium rolfsii Sacc. was isolated from the affected leaves using acid potato dextrose agar (APDA) (1). Two plastic boxes were lined with wet paper towels and 6 uninoculated leaves were placed in each. Three leaves in each box were treated as controls and received 3 mm2 of APDA, while the other three leaves in each box received 3 mm2 of S. rolfsii culture on APDA. All leaves were misted with water and enclosed to maintain humidity. Twenty-four hours later, infection was visible on two treated leaves. Within 72 h, significant infection was visible on three of the six inoculated leaves. All control leaves remained uninfected. S. rolfsii was consistently reisolated from the inoculated leaves, fulfilling Koch's postulates. Over the past 12 months, S. rolfsii has been detected in 30% of commercial orchid nurseries as well as homeowner orchid collections in Miami-Dade County, Florida. No resistance to this disease in orchids has been reported. To our knowledge, this is the first report of S. rolfsii on this orchid hybrid. Reference: (1) J. Tuite. Media and nutrient solutions used by plant pathologist and mycologist. Page 53 in: Plant Pathological Methods Fungi and Bacteria. Burgess Publishing Company, Minneapolis, MN, 1969.
First Report of “Candidatus Liberibacter asiaticus”, the Agent of Citrus Huanglongbing (Ex-greening) in Bhutan
Authors: Doe Doe , Om Namgay , Dorji Chencho , Dorji Thinlay , Garnier M. , Jagoueix-Eveillard S. , Bové J. M. 
Published: May 2007

Mandarin (Citrus reticulata) is the most important cash crop in Bhutan and plantations total approximately 1.8 million trees (Ministry of Agriculture, Thimphu, Bhutan, 2000). Most trees are a local mandarin variety. Seedlings trees are produced by local farmers or supplied by Druk Seed Nursery. Mandarin seedlings have also been introduced from India. In the mid-1990s, mandarin trees growing in Punakha Valley and Wangdue districts began showing symptoms of decline that included sparse yellow foliage and shoot die-back. After initial surveys in 2000, huanglongbing (HLB) was suspected as the cause of declining trees based on symptomatology and presence of the psyllid vector Diaphorina citri, but no confirmatory tests were carried out. In August 2002, we surveyed eight locations in the valley from Rimchu (North) to Kamichu (South). HLB-like leaf mottle symptoms were observed on declining mandarin trees at all locations at altitudes ranging from 700 to 1,450 m. Orchards around Punakha (1,350m) in the center of the valley were more severely affected. Symptoms were also observed on Mexican lime (Citrus aurantifolia), citron (Citrus medica), and on tangelo trees (Minneola, Seminola, and Iyo) introduced originally as certified HLB-free budwoods from Corsica, France and grafted onto Rangpur lime at the Wangdue Research Center (1,300m). Leaves were collected from symptomatic trees and three declining mandarin trees without characteristic leaf mottle symptoms. Two specific polymerase chain reaction (PCR) tests for the detection of HLB Liberibacter species (1,2) were carried out on 16 DNA samples extracted from leaf mid-veins of 10 mandarins, two Mexican limes, three tangelos, and one citron tree. “Candidatus Liberibacter asiaticus” was readily detected by both PCR assays in all but two samples (one mandarin with noncharacteristic symptoms and citron) and all sampled orchards. The presence in the Wangdue Research Center of liberibacter infected trees, propagated from certified HLB-free budwoods, suggests that natural spread of the HLB by D. citri is occuring, as the psyllid had been identified previously in the Punakha area by Bhutanese Entomologists. It is likely that the disease was originally introduced as infected planting material although its source has not been determined. References: (1) A. Hocquellet et al. Mol. Cell. Probes 13:373, 1999. (2) S. Jagoueix et al. Mol. Cell.Probes 10:43,1996.
First Report of Citrus Greening Disease and Associated Bacterium “Candidatus Liberibacter asiaticus” from Bhutan
Authors: Ahlawat Y. S. , Baranwal V. K. , Thinlay  , Doe Doe  , Majumder S. 
Published: May 2007

During July 2002, surveys of mandarin orchards were conducted in Punakha Valley and Wangdue districts of Bhutan. Symptoms of the greening disease were observed in most of the orchard. The incidence of disease was recorded up to 30% in 24 private orchards with more than 5,000 trees total. Affected trees were generally stunted with leaves showing symptoms of mottling. Sometimes, symptoms were seen only on one part of the canopy. The greening disease is caused by a fastidious phloem restricted bacterium, “Candidatus Liberibacter asiaticus” in Asian countries and “Candidatus Liberibacter africanus” in African countries. To confirm the presence of this bacterium causing greening disease in Bhutan, 33 leaf samples were collected from seven locations in Bhutan and stored at -80°C. Petioles and midribs were used for extraction of DNA using DNeasy Plant Mini Kit (Qiagen Gmbh, Hilden, Germany). Polymerase chain reaction (PCR) was initially performed with a sample from Rimchu, Bhutan using primer pair 5′TATAAAGGTTGACCTTTCGAGTTT/5′ACAAAAGCAGAAATAGCACGAACAA previously designed for amplification of ribosomal protein genes of β-operon of two liberibacter species (1). An amplicon of approximately 700 bp was obtained. The size of the PCR product is similar to that amplified from “Candidatus Liberibacter asiaticus”. The amplicon was cloned in pGEM-T easy vector and sequenced. The clone was 703 nt long and showed 100% sequence homology with the corresponding sequence of “Candidatus Liberibacter asiaticus” confirming that “Candidatus Liberibacter asiaticus” is the cause of greening disease in Bhutan. Later, one sample from each location was analyzed and found to be positive to greening. To our knowledge, this is the first report of this bacterium and greening disease in Bhutan, and citrus greening appears to be the main cause of declining citrus in the Punakha Region of Bhutan. Reference: (1) A. Jocquellet et al. Page 363 in: Proc. Conf. Int. Organ. Citrus Virol. 14th. IOCV, Riverside, CA, 2000.
Pathogenicity on Chile Pepper of Vertcillium dahliae Recovered from Three Weed Hosts in New Mexico
Authors: Sanogo S. , Clary M. 
Published: May 2007

In July 2002, in the course of field surveys for Verticillium dahliae in chile pepper (Capsicum annuum), three weed species, Physalis wrightii (Wright groundcherry), Anoda cristata (spurred anoda), and Proboscidea louisianica (devil's-claw), were found with symptoms of vascular necrosis in three fields in Luna County and two fields in each Hidalgo and Doña Ana counties in southern New Mexico. Across the three weed species, vascular area with necrosis was approximately 5 to 15%, and was rated on longitudinal crown and stem sections (1). Except for a few plants of P. wrightii that had leaves with necrotic margins in one field in Luna County, no other symptoms were observed. The three weed species were at growth stages between flowering and fruit set. Isolates recovered from the vascular tissue were identified as V. dahliae based on morphological features when cultured on prune extract medium (2). Two isolates of V. dahliae from each weed species, along with an isolate from chile pepper, were grown on potato dextrose agar at 20, 25, or 30°C for 12 days. There was no significant difference in radial growth among isolates at the three temperatures, and maximum radial growth occurred at 25°C. The isolates were tested for pathogenicity on the chile pepper cv. NM 6-4 in the greenhouse. In each of the three trials, 15 plants were inoculated each by root dipping (1) in 20 ml conidial suspension (106 conidia/ml) of each V. dahliae isolate. Control plants were root dipped in sterile distilled water. Symptoms of foliar wilting with 75 to 100% vascular necrosis (1) were observed in all plants 4 weeks after inoculation. V. dahliae was recovered from symptomatic plants (2). To our knowledge, this is the first report that V. dahliae recovered from P. wrightii, A. cristata, and Proboscidea louisianica is pathogenic to chile pepper. Control of Wright groundcherry, spurred anoda, and devil's-claw may be important in the management of V. dahliae in chile pepper. References: (1) R. G. Bhat and K. V. Subbarao. Phytopathology 89:1218, 1999. (2) P. W. Talboys. Plant Pathol. 9:57, 1960.
First Report of Sharp Eyespot of Wheat in Egypt
Authors: Hammouda A. M. 
Published: May 2007

In 1998 and 1999, Rhizoctonia solani Kühn and R. cerealis van der Hoeven were isolated from lesions on basal leaf sheaths (2 to 4 cm above the soil level) of 48 wheat plants (Triticum aestivum L. em. Thell.). Plants were collected from 16 locations in Egypt in December 1998 (seedling stage) and March 1999 (adult stage). Disease incidence was approximately 20 and 30% during the 1998 to 1999 and 1999 to 2000 seasons, respectively. Mycelium was white to deep brown, branched at right angles with a septum near the branch, and a slight constriction at the branch base. Multinucleate cells and the production of irregular, brown black sclerotia in culture and on host plants were diagnostic of R. solani (1). Anastomosis groups AG-4 (30 isolates) and AG-1 (6 isolates) of R. solani, distinguished on the basis of hyphal fusion, were recovered. R. cerealis (12 isolates belonging to the anastomosis group CAG-1), which were slow-growing on potato dextrose agar, produced binucleate hyphal cells and yellow sclerotia. The 48 isolates were tested in the greenhouse for pathogenicity using cornmeal and sand inoculum prepared by mixing 3 g of infested cornmeal, 100 g of sand, and 20 ml of distilled water and incubating for 20 days at 28°C. Fifty milliliters of inoculum were added to 500 g of sterile soil in a 15-cm-diameter pot. There were six pots per isolate. Six pots containing noninfested soil were included as checks. Wheat (cv. Giza 160) seeds were disinfested by placing them in 5% of sodium hypochlorite for 5 min, and 10 seeds were planted in each pot. Twenty-five days after planting, an average of five plants survived in the pots treated with R. solani, and seven plants survived in pots treated with R. cerealis. All 10 plants in the noninfested pots survived and were symptomless. The surviving plants treated with R. solani developed a tan cortical rot of the root system and tan zonate lesions on the basal leaf sheaths. The lesions were oriented longitudinally with the stem and were irregular in shape with a white or light tan center surrounded by a wide, dark brown margin. Isolates of R. cerelis caused lesions on the base of the stem of young and mature plants. The lesions, which were larger than those caused by R. solani, were elliptic or “eye” shaped with a pale yellow center and sharply defined narrow border. The fungi were reisolated from the symptomatic tissue. Reference: (1) J. D. S. Clarkson and M. J. Griffin. Plant Pathol. 26:98, 1977.