bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of Citrus tristeza virus in Greece
Authors: Dimou D. , Drossopoulou J. , Moschos E. , Varveri C. , Bem F. 
Published: May 2007

Large-scale surveys of Citrus spp. for the presence of Citrus tristeza virus (CTV) by the Ministry of Agriculture in Greece began in 1995. Over 26,000 trees have been tested by enzyme-linked immunosorbent assay and immunoprinting (2). In summer 2000, the first CTV-infected sweet orange cv. Lane Late tree grafted on CTV-tolerant Carrizo citrange was found in Argolis County, Peloponnese. This tree belonged to a batch of CAC propagation material (20 trees) illegally introduced from Spain in 1994, which was subsequently traced and found to be infected (45%). A follow-up search of trees grafted with the above material was undertaken in the two concerned regions (Argolis and Chania-Crete), and more than 3,500 trees have been removed. Extensive surveys continue to identify and destroy new infections. Few cases (15 of 16,800) of natural transmission to cultivars other than cv. Lane Late have been found. All of these have been close to the initially infected trees in the Argolis area. Surveys in spring 2001 were extended to certified propagation material of Clemenpons mandarin on Carrizo citrange imported from Spain, and 7 of 1,038 plants were infected (0.64%). The virus was successfully graft-transmitted to sweet orange cv. Madame Vinous and sweet lime seedlings, where it was identified by immunoprinting and reverse transcription-polymerase chain reaction (1). Mild vein clearing symptoms appeared on both indicators. Vein clearing on sweet lime was also accompanied by leaf cupping. To our knowledge, this is the first report of CTV in Greece. References: (1) A. Sambade et al. J. Virol. Methods 87:25, 2000. (2) C. Vela et al. J. Gen. Virol. 67:91, 1986.
First Report of an Aster Yellows Subgroup 16SrI-B Phytoplasma Infecting Chayote in Costa Rica
Authors: Villalobos W. , Moreira L. , Rivera C. , Bottner K. D. , Lee I.-M. 
Published: May 2007

An outbreak of a witches' broom disease affected approximately 20% of plants in several chayote (Sechium edule (Jacq.) Schwartz) fields in the commercial production area of the Ujarrás Valley, Cartago Province, Costa Rica during 2000 and 2001. Affected chayote plants exhibited symptoms, including basal proliferation with severe foliage reduction, aborted flowers, and deformed fruits, suggestive of phytoplasmal infection. Two other symptomatic cucurbit species growing near the chayote fields were also identified. These species were tacaco plants (S. tacaco (Pitt.) C. Jeffrey), an edible cucurbit for domestic marketing in Costa Rica, showing severe size reduction of leaves and fruits, and Rytidostylis carthaginensis (Jacq.) Kuntze, a weed in chayote and tacaco fields, exhibiting abnormal tendril proliferation. Plants were analyzed for phytoplasma infection by a nested polymerase chain reaction (PCR) assay, using the universal rRNA primer pair P1/P7 followed by R16F2n/R16R2 (2). Phytoplasmas were detected in all symptomatic samples (18 chayote, 6 tacaco, and 3 weed) tested but were undetectable in all asymptomatic samples (10 chayote, 6 tacaco, and 2 weed). Restriction fragment length polymorphism (RFLP) analysis of PCR products (16S rDNA sequences) by separate digestion with eight restriction enzymes (RsaI, HhaI, KpnI, BfaI, HaeIII, HpaII, AluI, MseI) revealed that a phytoplasma belonging to subgroup 16SrI-B in the aster yellows phytoplasma group (16SrI) was associated with chayote witches' broom (CWB). The same or very similar phytoplasmas were found in both symptomatic tacaco and R. carthaginensis plants. Phylogenetic analysis of 16SrDNA sequences also confirmed the CWB phytoplasma to be most similar to members of subgroup 16SrI-B. Similar diseases in chayote and other cucurbits have been reported in Brazil (3), Taiwan (1), and Mexico (4). The CWB phytoplasma differs from the phytoplasma (16SrIII-J subgroup) associated with chayote in Brazil. The identities of phytoplasmas associated with cucurbits in Taiwan and Mexico are unknown. The occurrence of an aster yellows group phytoplasma in chayote may pose a potential threat to continued production and exportation of this cash crop. To our knowledge, this is the first report of 16SrI-B subgroup phytoplasmas in naturally infected cucurbits in Costa Rica. References: (1) T. G. Chou et al. Plant Dis. Rep. 60:378, 1976. (2) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) H. G. Montano et al. Plant Dis. 84:429, 2000. (4) E. Olivas. Rev. Fitopatol. (Lima) 13:14, 1978.
First Report of Phytoplasmas Infecting Watercress in Hawaii
Authors: Borth W. B. , Hamasaki R. T. , Ogata D. , Fukuda S. K. , Hu J. S. 
Published: May 2007

Symptoms of leaf yellowing, reduced leaf size, and witches'-brooms have recently been observed affecting watercress (Nasturtium microphyllum Boen. × Rcbh.) in Hawaii. These symptoms are followed by the collapse of affected plants. This condition has led to 80 to 90% losses for one of the largest watercress farms on Oahu and is now affecting other watercress farms in the area. Nutritional deficiencies or toxicities, water salinity, and insect or mite feeding damage were investigated but could not be implicated in the etiology of this syndrome. Eighteen watercress plants with early yellowing or advanced symptoms and nine symptomless plants were analyzed for phytoplasma infection using polymerase chain reaction (PCR) assays with primer pairs P1/Tint or P1/P7 (4). Amplicons of the expected sizes were produced from all symptomatic plants, whereas no products were amplified from symptomless plants. Sequence analysis of the cloned PCR products confirmed their phytoplasma origin and indicated that the watercress was infected with a phytoplasma most similar to SAY (2), a severe strain of western aster yellows phytoplasma previously classified as a 16SrI-B group member (3). Leafhoppers collected from an affected watercress planting have been identified as the aster leafhopper (Macrosteles quadrilineatus Fbs.) This species is the most efficient vector of the aster yellows phytoplasma and had not been previously recorded in Hawaii. The only other phytoplasma disease known in Hawaii prior to this report is Dodonaea yellows (1), which affects one of the most common native plants (Dodonaea viscosa (L.) Jacq.) in dry upland forests on all the islands. Dodonaea yellows, however, has been attributed to an X-disease (16SrIII) group phytoplasma. The occurrence of an aster yellows group phytoplasma in watercress, a previously unrecorded host, and the presence of a very efficient vector, M. quadrilineatus, poses a serious threat to the production of other vegetable and floral crops in Hawaii. References: (1) W. Borth et al. Plant Dis. 79:1094, 1995. (2) C. Kuske and B. Kirkpatrick. Int. J. Syst. Bacteriol. 42:226, 1992. (3) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (4) C. Smart et al. Appl. Environ. Microbiol. 62:2988, 1996.
Phlyctema vagabunda Isolated from Coin Canker of Ash Trees in Michigan
Authors: Rossman A. Y. , Castlebury L. A. , Adams G. C. , Putnam M. L. 
Published: May 2007

The coelomycetous fungus Phlyctema vagabunda Desm. (teleomorph Neofabraea alba (E.J. Guthrie) Verkley, synonym Pezicula alba E.J. Guthrie) is associated with a serious canker disease of cultivated ash trees in Michigan. Four- to five-year-old trees of Fraxinus americana cv. Autumn Purple and F. pennsylvanica cvs. Champ Tree, Cimmaron, and Urbanite had cankers that were smooth, round, brownish yellow, approximately 2 to 4 cm in diameter with distinct reddish, cracked margins. Immersed, eventually erumpent, unilocular acervuli developed in the central portions of these cankers. The same fungus was isolated both from the conidia as well as from the margin of the canker. The internal transcribed spacer (ITS) (AY064704) and beta-tubulin (AY064702) sequences were identical to sequences identified in GenBank as Pezicula alba from apple (1), and the morphology was consistent with Phlyctema vagabunda as well (2). P. vagabunda has been studied primarily as the cause of Bull's eye canker of apple (1). P. vagabunda under its numerous synonyms has been reported on various hardwood and herbaceous hosts from temperate regions around the world, including the United States. However, it has not been reported previously on species of Fraxinus. A specimen and culture from the ash cankers in Michigan have been deposited (BPI 841384 and CBS 109875). References: (1) S. N. De Jong et al. Mycol. Res. 105:658, 2001. (2) B. C. Sutton. The Coelomycetes. CMI, Kew, Surrey, UK, 1980.
First Report of Bacterial Fruit Blotch of Watermelon Caused by Acidovorax avenae subsp. citrulli in Illinois
Authors: Babadoost M. , Pataky N. 
Published: May 2007

In August 2001, symptomatic mature fruit of watermelon (Citrullus lanatus) cvs. Crimson Sweet and Royal Sweet were collected from six fields (48 ha) in Iroquois, Kankakee, and Mason counties in Illinois. The fruit surface had dark green, water-soaked lesions, and the rind's epidermis was cracked. Sections of infected rind were examined with a light microscope, and bacterial streaming was observed. Rind tissue was disinfested by rubbing the fruit surface with a paper towel moistened with 70% ethanol. Pieces of rind from the margins of lesions were placed in a test tube containing sterile-distilled water. The tube was shaken, and the suspension was streaked on King's medium B agar in petri plates. The plates were incubated at 26°C for 3 days. A nonfluorescent, gramnegative, anaerobic, oxidase-positive, rod-shaped bacterium was isolated that produced creamy white colonies on nutrient agar. The bacterium was identified as Acidovorax avenae subsp. citrulli based on an enzyme-linked immunosorbent assay test specific for A. avenae subsp. citrulli (kit PSA 14,800; Agdia Inc., Elkhart, IN). The disease was diagnosed as bacterial fruit blotch (1,2). The occurrence of bacterial fruit blotch of watermelon in Illinois is important because (i) watermelon is widely grown in Illinois, (ii) the pathogen also infects melons and pumpkins, and (iii) Illinois grows approximately 1,000 ha of melons and 8,000 ha of pumpkins. References: (1) R. X. Latin. Bacterial fruit blotch. Pages 34-35 in: Compendium of Cucurbit Diseases. The American Phytopathological Society, St. Paul, MN,1996. (2) G. S. Somodi et al. Plant Dis. 75:1053, 1991.
First Report of Black Branch Dieback of Cashew Caused by Lasiodiplodia theobromae in Brazil
Authors: Cardoso J. E. , Vidal J. C. , Santos A. A. dos , Freire F. C. O. , Viana F. M. P. 
Published: May 2007

Cashew nut (Anacardium occidentale) is one of the most important cash crops of northeastern Brazil. A new disease, named here as black branch dieback, caused by Lasiodiplodia theobromae, was observed causing serious damage on as many as 30% of the trees in some orchards in both coastal and inland semiarid cashew-growing areas of Ceará and Piauí states of Brazil, respectively. The disease symptoms are first observed as darkened, elongated lesions on stems near the branch apexes of herbaceous tissues. Gum exudation is common from lesions, which expand rapidly to affect the entire branch, leading to branch death. Diseased plants were collected, and L. theobromae was consistently isolated from canker tissues. Fresh mycelial disks of the fungus were used for artificial inoculation of healthy plants. Shoots of young cashew plants were inoculated on the apex by inserting a 3-mm plug taken from actively growing colonies on potato dextrose agar into an incision made with a sterile scalpel. Agar plugs with no mycelium were placed into incised plant shoots to serve as controls. Plants were incubated in a greenhouse at 28°C. Symptoms developed within 15 days after inoculation. Artificially inoculated plants showed symptoms similar to those that were naturally infected. L. theobromae was consistently reisolated from inoculated plants. The disease seems to occur throughout the year, but it spreads faster during the rainy season. A contagious disease pattern within the orchard was observed with a decreasing gradient from the orchard perimeter to the interior of the field, suggesting an external source of primary inoculum. All improved dwarf cashew clones were susceptible, but the newly released clone END-189 was the most susceptible. Black branch dieback may reduce tree growth, nut yield, and eventually cause plant death. Plant susceptibility is not related to its age however; only herbaceous tissues are vulnerable to natural infection. A similar disease on floral shoots of cashew caused by L. theobromae was reported by Olunloyo and Esuruoso in Nigeria (1). To our knowledge, this is the first report of L. theobromae causing branch dieback in cashew orchards in Brazil. Reference: (1) O. A. Olunloyo and O. F. Esuruoso. Plant Dis. 59:176, 1975.
Aphanomyces euteiches Race 2 in Central Illinois Alfalfa Fields
Authors: Malvick D. 
Published: May 2007

Approximately 260,000 ha of alfalfa is grown in Illinois. Two soil samples were collected randomly from slowly drained thin patches in each of four established alfalfa fields near Urbana in 2001. Plants in the thin patches were asymptomatic. Aphanomyces euteiches Drechs. was baited from the soil with cv. Saranac alfalfa seedlings and was isolated from 3- to 4-week-old infected seedlings using a medium containing metalaxyl and benomyl (1,2). It is difficult to isolate A. euteiches from field-grown roots. One to seven isolates were obtained per field, and all were identified as A. euteiches based on morphology (1,2). A. euteiches (races R1 and R2) causes root rot of alfalfa in slowly drained fields in Iowa, Kentucky, and Wisconsin (1,2). The race of 13 isolates was determined in tests repeated once with alfalfa populations Saranac (susceptible to R1 and R2), WAPH-1 (resistant only to R1), and WAPH-5 (resistant to R1 and R2) (1). Twelve 7-day-old seedlings in each of three pots per population were inoculated with 103 zoospores per seedling in a growth chamber (25°C). A disease index (DI) was determined 12 days later by scoring plants on a 1 to 5 scale, where 5 is a dead plant (1). Race was based on DI, R1: DI ≥3 for Saranac and <3 for WAPH-1, and R2: DI > 3 for Saranac and WAPH-1. The DI was 1.0 for noninoculated plants. All isolates were R2; the DI was >3.0 for inoculated Saranac and WAPH-1 and <3.0 for WAPH-5. To our knowledge, this is the first report of A. euteiches races in Illinois, and this pathogen was reported previously only from northwest Illinois. Control of Aphanomyces root rot is based on resistance; however, few alfalfa cultivars are resistant to R2. References: (1) D. Malvick and C. Grau. Plant Dis. 85:740, 2001. (2) G. Munkvold and W. Carlton. Plant Dis. 79:1251,1995.
First Report of Pycnostysanus azaleae on Rhododendron in Italy
Authors: Garibaldi A. , Gilardi G. , Bertetti D. , Gullino M. L. 
Published: May 2007

Rhododendron species cultivation has a long history in northern Italy, where a wide selection of cultivars and hybrids is grown. In spring 2001, a previously unknown bud blast was observed on several rhododendron cultivars growing in gardens and parks in the Province of Biella, Italy. Flower petioles and twigs, but not leaves, showed extensive necrosis, and flower production was reduced. The first symptoms on infected flower buds are brown necrotic areas near the base, which increase in size until the whole bud appears brown and water-soaked. Infected buds shrink, but do not rot or disintegrate, and remain on the bush. Coremia (2.0 mm high and 0.5 mm wide), which appeared as black specks on outer bud scales, produced large numbers of spherical spores apically that measured 3.6 to 5.5 μm in diameter. The fungus Pycnostysanus azaleae (1) was consistently isolated after disinfested infected buds (1 min in 5.15% commercial NaOCl solution) were cultured on potato dextrose agar amended with streptomycin sulfate at 100 mg/liter. Pathogenicity of three isolates of P. azaleae was confirmed by inoculating with a spore suspension 30 buds of 2 rhododendron plants (cv. Rosso scuro grande tardiva) grown in containers (14 cm diameter). Buds were punctured with a sterile needle before inoculation. Noninoculated plants served as controls. Wounded buds were covered with plastic bags to maintain high relative humidity, and all plants were maintained in growth chambers at 20°C for 9 days, and then transferred outdoors where temperatures were 20 to 25°C. Inoculated plants developed typical bud symptoms 20 days after inoculation, with 80% of inoculated buds showing symptoms. Control plants remained symptomless. The pathogen was consistently reisolated from artificially inoculated plants. In garden observations, different cultivars showed a wide range of susceptibility to the pathogen, mainly related to their flowering period. To our knowledge, this is the first report of the presence of P. azaleae in Italy. Outbreaks of P. azaleae were previously reported in the United States (1), United Kingdom (2), and Germany (3). References: (1) W. H. Davis. Phytopathology 29:517, 1939. (2) P. J. Howell and R. K. S. Wood. Ann. Appl. Biol. 50:723, 1962. (3) W. Schmalscheidt. Immergrune Blater 26:35, 1985.
Occurrence of Black Dot of Potato Caused by Colletotrichum coccodes in Central Italy
Authors: Buonaurio R. , Natalini G. , Covarelli L. , Cappelli C. 
Published: May 2007

Between 1997 and 2000, black dot of potato (Solanum tuberosum L.), caused by the polyphagous soilborne fungus Colletotrichum coccodes (Wallr.) Hughes, was observed each summer in fields located in Umbria (central Italy). Disease incidence ranged from 50 to 100%, and early potato cultivars were generally more susceptible than late-maturing ones. Disease symptoms were first observed during August as a yellowing and wilting of foliage in the tops of plants, followed by rotting of the roots and stems, which led to the premature death of 50 to 70% of plants. Setose1 sclerotia (300 to 500 mm in diameter) and acervuli of the fungus were found on roots and stems of infected plants. Acervuli produced hyaline, aseptate, cylindrical conidia (16 to 22 × 2.5 to 4.5 μm) formed on unicellular cylindrical phialidic conidiophores. The fungus was isolated from diseased stems and roots on potato dextrose agar (PDA) at pH 6.5. Pathogenicity of the fungus was confirmed by fulfilling Koch's postulates using 3- to 4-week-old potato plants of a local cultivar. A superficial 5-mm vertical cut was made with a scalpel into the base of potato stems (2 cm beneath the soil surface), and 5-mm-diameter plugs of PDA alone (control plants) or PDA plus fungal growth were placed over the cuts. The wounds were sealed with wet cotton swabs that were held in place with Parafilm. Symptoms that resembled those in the field were observed on inoculated plants 6 to 8 weeks postinoculation. Symptoms did not appear on the control plants. The same fungus was reisolated from the diseased plants. Based on morphological characteristics of sclerotia, acervuli, and conidia, as well as pathogenicity tests, the fungus was identified as C. coccodes. To our knowledge, this is the first report of C. coccodes as the causal agent of black dot of potato in central Italy. We did not observe foliar outbreaks of the disease, which were reported from the United States (2). In both 1921 (1) and 1951 (3), the fungus was reported to cause severe outbreaks of the disease in northern Italy. Since then, its presence in Italy has been rarely recorded in potato (4). The occurrence of extremely dry and hot weather conditions during the summers of 1997 to 2000, which are favorable for disease development, made the disease particularly severe. We cannot exclude the possibility that the disease may have been present in central Italy before our observations, as it can be misdiagnosed and its symptoms can be masked by the symptoms of other diseases. The significance of black dot in central Italy needs to be reappraised in terms of both yield loss and tuber quality. References: (1) C. Arnaudi. Atti Ist. Bot. Univ. Pavia. Ser. 3, 1:71, 1924. (2) A. W. Barkdoll and J. R. Davis. Plant Dis. 76:131, 1992. (3) G. Goidanich. Inf. Fitopatol. 1:5, 1951. (4) S. Vitale et al. J. Plant Pathol. 80:265, 1998.
First Report of Stolbur Phytoplasma in Avocado in Spain
Authors: Laviña A. , Batlle A. , Faraco J. Garcia , Herrera C. J. López 
Published: May 2007

Since its introduction to southern Spain in the late 1970s, avocado (Persea americana Mill.) has become an alternative irrigation crop to more traditional and less productive dry land crops such as olive, almond, and grapevine. Avocado orchards in this region currently cover an area of 7,500 ha, producing 58,000 tons of fruit in 2000, with 42,000 tons exported annually to the European Union. In summer 1999, symptoms similar to those caused by phytoplasmas were observed in a plot of avocado cv. Hass. Symptoms of leaf roll, leaf veinal chlorosis with the leaves becoming small and abnormally red, and dwarfing were irregularly distributed on affected trees. Host species of phytoplasmas, such as Lavandula officinalis and Thymus officinalis, are found (1) in orchards surrounded by Mediterranean forests. Leaves from eight symptomatic plants taken from affected plots and leaves from two symptomless plants taken from a healthy plot were collected in May, July, and October 2000, and analyzed for phytoplasma infection by polymerase chain reaction (PCR) assays. DNA for PCR was prepared from leaf petioles, midribs, or trunk phloem by phytoplasma-enrichment fraction according to Daire et al. (2). The stolbur phytoplasma was detected in trees by PCR using stolbur-specific nonribosomal primer pair stol 4 f/r (3) or by nested PCR with 16S rDNA primers pairs P1/P7 and fU5/rU3. Phytoplasmas were detected only in samples collected in July. Phytoplasmas were detected by universal primers in all symptomatic samples analyzed in July, whereas stolbur-specific primers gave positive results in only 75% of the symptomatic samples. Restriction fragment length polymorphism (RFLP) analysis with enzymes AluI and Tru9I confirmed the phytoplasma belonged to the stolbur group. To our knowledge, this is the first description of a phytoplasma disease of avocado trees in Spain. Stolbur is the most important vector-borne disease caused by phytoplasma in several crops. In Spain, it has been identified in various crops and weeds such as grapevine, pear, tomato, carrot, pepper, chicory, and strawberry, and appears to be ubiquitous in herbaceous plant host in several families. Rigorous control of stolbur in avocado should be implemented as soon as possible to avoid further disease development and subsequent economic damage to this industry. References: (1) A. Batlle et al. Eur. J. Plant Pathol. 106:811, 2000. (2) X. Daire et al. Ann. Appl. Biol. 121:95, 1992. (3) X. Daire et al. Eur. J. Plant Pathol. 103:507, 1997.