bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of Aster Yellows Phytoplasma in Alfalfa
Authors: Peters R. D. , Lee M. E. , Grau C. R. , Driscoll S. J. , Winberg R. M. , Kurtzweil N. C. , Lukaesko L. A. , Lee I.-M. 
Published: May 2007

Samples of alfalfa (Medicago sativa L.) leaves and stems showing symptoms of inter-veinal chlorosis and purpling, commonly associated with insect feeding, were collected from 8 sites in central and southern Wisconsin in autumn of 1998. Samples were frozen within 24 h of collection. Approximately 0.3 g of plant tissue from each sample was used for total DNA extraction according to the protocol of Zhang et al. (4), with minor modifications in grinding procedures and reagent volumes to optimize results. Nested polymerase chain reaction (PCR) was carried out by amplification of 16S rDNA with the universal primer pairs R16mF2/R16mR1 followed by R16F2n/R16R2 as described by Gunder-sen and Lee (1). Undiluted total sample DNA was used for the first amplification; PCR products were diluted (1:30) in sterile water prior to final amplification. Alfalfa DNA and sterile water were used as negative controls; DNA from phytoplasma causing X-disease in peach (CX) served as a positive control. Fragments of 16S rDNA from putative phytoplasmas amplified by PCR with the primer pair R16F2n/R16R2 were characterized by restriction endonuclease digestion (3). The resulting restriction fragment length polymorphism (RFLP) patterns were compared with patterns for known phytoplasmas described by Lee et al. (3). Products of nested PCR were also purified and sequenced with primers R16F2n/R16R2 and an automated DNA sequencer (ABI 377XL; C. Nicolet, Biotechnology Center, University of Wisconsin-Madison). Of 51 samples of alfalfa assessed, one sample from Evansville, WI, yielded a nested PCR product of the appropriate size (1.2 kb), indicating the presence of phytoplasma. Digestion of this product with various restriction enzymes produced RFLP patterns that were identical to those for phytoplasmas in the aster yellows phytoplasma subgroup 16SrI-A (3). Alignment of the DNA sequence of the nested PCR product from the positive sample with sequences found in the GenBank sequence data base (National Center for Biotechnology Information, Bethesda, MD) with the BLAST sequence similarity function confirmed this result. Although other phytoplasma strains (particularly those causing witches'-broom) have been reported to infect alfalfa (2), this is the first report of the presence of the aster yellows phytoplasma in the alfalfa crop. Vectors involved in transmission and the potential agronomic impacts of aster yellows phytoplasma in alfalfa are topics of current investigation. References: (1) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (2) A.-H. Khadhair et al. Microbiol. Res. 152:269, 1997. (3) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (4) Y.-P. Zhang et al. J. Virol. Methods 71:45, 1998.
First Report of Fusarium Wilt Disease of Mimosa in Greece
Authors: Skarmoutsou H. , Skarmoutsos G. 
Published: May 2007

Mimosa, Albizia julibrissin, is an ornamental tree that thrives in Greece under difficult urban environmental conditions and is prized for its ability to create alleys. In 1991, at Kalamaria municipality, Thessaloniki, mimosa trees were found with symptoms of a Fusarium wilt disease and many trees were already dying or dead. The first symptom was a characteristic yellowing and wilting of foliage. Leaves on symptomatic trees fell prematurely and eventually the defoliated portion of crowns died. Numerous adventitious branches on the stems also developed wilt symptoms and died. When stems were cross-sectioned, a brownish discoloration in the spring wood vessels of the outer annual ring could be observed. In the more advanced stages of the disease, dark sap exudations flowed out of bark cracks. Orange-pink sporodochia with masses of conidia developed in bark cracks and lenticels. Of 1,520 trees examined for external symptoms in the autumn of 1991, 1,339 (88.2%) were apparently healthy, 96 (6.3%) had symptoms, and 85 (5.6%) were dead. In autumn 1992, the same trees were examined and the respective values were 1,276 (83.9%), 130 (8.6%), and 114 (7.5%). Wood samples from the most recent annual ring taken from 30 infected and 30 apparently healthy trees were plated on potato dextrose agar. Fusarium oxysporum was recovered from 93% of the symptomatic trees and only 7% of the asymptomatic ones. Since 1992, the disease has spread within the area where it was first found but has not been observed anywhere else in Greece. A disease of mimosa with similar symptoms was first reported by Hepting (1) in 1936 from North Carolina. The associated fungus Fusarium oxysporum f. sp. perniciosum was described by Hepting (2), who also demonstrated its pathogenicity. The disease has also been previously reported in Russia. This is the first report of mimosa wilt disease in Europe. References: (1) G. H. Hepting. Plant Dis. Rep. 20:177, 1936. (2) G. H. Hepting. USDA Circ. 535, 1939.
First Report of Pyrenophora tritici-repentis Race 5 from North America
Authors: Ali S. , Francl L. J. , De Wolf E. D. 
Published: May 2007

Tan spot, caused by Pyrenophora tritici-repentis, is an important foliar disease of wheat worldwide. The fungus produces two distinct symptoms, necrosis (nec) and chlorosis (chl), on susceptible wheat genotypes. Fungal isolates have been grouped into five races based on their ability to induce necrosis and/or chlorosis on differentials Glenlea, Katepwa, 6B365, and Salamouni (1). Moreover, the isolates were designated on their ability to induce necrosis and chlorosis as follows: nec+chl+ (necrosis and chlorosis), nec+chl- (necrosis only), nec-chl+ (chlorosis only), and nec-chl- (neither symptom). Races 3 and 5 induce extensive chlorosis (nec-chl+) on 6B365 and Katepwa, respectively. Race 5 was reported on durum from North Africa. Races 1 to 4 were described from North America (1,2). During 1998, a survey of durum fields was conducted in the primary durum-growing area of North Dakota to assess the virulence pattern of P. tritici-repentis. Fifty-two single-spore isolates were obtained from diseased leaves. The isolates were evaluated for their virulence by inoculating them individually onto 15 seedlings of each wheat differential in the greenhouse. Forty-nine of 52 isolates were grouped as race 1 (nec+chl+) and three isolates, obtained from the Langdon Experiment Research Station, were grouped as race 5 (nec-chl+). Race 5 isolates were evaluated three times and consistently induced extensive chlorosis on Katepwa. This is the first report of the occurrence of race 5 outside of North Africa. This race may threaten wheat in the United States, so cultivars and germplasm should be evaluated for resistance. More isolates are under investigation to obtain a comprehensive virulence pattern of the pathogen population in the United States. References: L. Lamari and C. C. Bernier. Can. J. Plant Pathol. 11:49, 1989; (2) L. Lamari et al. Can. J. Plant Pathol. 17:312, 1995
Outbreak of Leaf Spot of Saponaria Caused by Alternaria saponariae in California
Authors: Koike S. T. , Henderson D. M. , Tjosvold S. A. , Simmons E. G. 
Published: May 2007

Saponaria (Saponaria vaccaria [= Vaccaria hispanica]) is a Caryophyllaceae plant that is grown commercially in California as a cut flower. In 1998, a leaf spot disease devastated the commercially grown saponaria in coastal California. The entire saponaria crop was completely unmarketable because of extensive leaf spotting. Symptoms consisted of circular, brown, necrotic leaf spots with diameters up to 8 mm and concentric zones of lighter and darker tissue. Chlorotic borders developed around the spots. Conidia from leaves were obclavate, usually had 7 transverse and 1 to 4 longitudinal septa, and narrowed gradually toward the apex into a blunt-tipped, unbranched beak cell. The spore body measured 69 to 90 (to 119) × 17 to 21 (to 25) μm, with the distinctive beak cell 17 to 53 μm long. Conidia formed short chains on host tissue. The fungus was identified as Alternaria saponariae (Peck) Neergaard (2). For pathogenicity tests, six representative isolates were grown on V8 juice agar under fluorescent tube lighting. Potted saponaria were sprayed with either conidial concentrations (1 × 10e5 conidia per ml) or water. Plants were incubated in a chamber with a humidifier for 48 h and then maintained in a greenhouse (23 to 25°C). After 14 days, leaf spots similar to the original symptoms developed on all inoculated plants, and the pathogen was reisolated. Plants sprayed with water were symptomless. The experiment was repeated and the results were similar. Using the same isolates and method, we inoculated carnation (Dianthus caryophyllus), sweet William (Dianthus barbatus), and saponaria. However, disease developed only on saponaria. While A. saponariae on saponaria was reported previously in California (1), this is the first report to characterize the pathogen and document that isolates are pathogenic on saponaria but not on other commercial Caryophyllaceae hosts. References: (1) K. F. Baker and L. H. Davis. Plant Dis. Rep. 34:403, 1950. (2) P. Neergaard. Aarsberet. J. E. Ohlsens Enkes Plantepat. Lab. No. 3, 1938.
The Distribution of Fusarium Wilt of Blackeyed Cowpeas within California Caused by Fusarium oxysporum f. sp. tracheiphilum Race 4
Authors: Smith S. N. , Helms D. M. , Temple S. R. , Frate C. 
Published: May 2007

Fusarium wilt of blackeyed cowpeas has been known in California since the 1930s, and breeding for resistance to this disease pathogen has been a continuous effort. During the 1960s and 1970s, California Blackeye 5 (CB 5) cowpea (Vigna unguiculata L. Walp.), a widely grown cultivar of the time, became increasingly diseased by Fusarium oxysporum f. sp. tracheiphilum (Fot) Race 3 (2) throughout the growing regions of California. University of California cultivars CB 46 and CB 88 (1) were developed for resistance to Fot Races 1, 2, and 3. CB 46 is currently the principal blackeye cultivar grown on the majority of the acreage in the San Joaquin Valley. In 1989, a new race we designate “Fot Race 4” was isolated from wilted plants at a single field site in Stanislaus County. In years prior to identification, Fot Race 4 had caused severe wilt of CB 46 and CB 88 in this field. Even though the new Fot Race 4 remained confined to a small area for a number of years, sources of host plant resistance to Fot Race 4 were identified, hybridized, and screened, resulting in new progeny with desirable commercial agronomic characteristics. As observed in Stanislaus County, F. oxysporum f. sp. tracheiphilum Race 4 has the potential to cause serious crop damage, depending on virulence and soil inoculum levels, which may vary from year to year. In 1997 and 1998, an entirely different area in the southern San Joaquin Valley, about 140 miles from the original site in Stanislaus County, was found to have plants infected with Fot Race 4. Diseased plants were collected from patches in three separate CB 46 or CB 88 field sites in Tulare County. About 30 cultures were isolated from the diseased plants, which showed stunting, yellowing, and vascular discoloration. In greenhouse fusarium dip tests CB 46, CB 88, CB 5, and several Fot Race 4 resistant breeding lines were inoculated with all the collected isolates and evaluated. CB 46, CB 88, and CB 5 proved to be susceptible to these isolates, showing typical Fot Race 4 symptoms. The Fot Race 4 pathogen was then reisolated from greenhouse-grown, diseased stem tissue of CB 46, CB 88, and CB 5. These findings emphasize the importance of vigilance and necessity of continual disease surveys. They serve as an early alert for the University of California breeding program, and validate local cooperation with University of California Extension Farm Advisors. As a result of this effort new cultivar candidates with resistance to Fot Race 4 are in the final phases of multi-year commercial testing. References: (1) D. M. Helms et al. Crop Sci. 31:1703, 1991. (2) K. S. Rigert and K. W. Foster. Crop Sci. 27:220, 1987.
First Report of Powdery Mildew on Cornus florida in Connecticut Caused by Microsphaera pulchra
Authors: Smith V. L. 
Published: May 2007

Powdery mildew of dogwood (Cornus florida L.) has been observed on landscape trees since 1992, and has been increasing in severity recently. In 1998, mildewed leaves (n = 100) were collected from each of four locations in Connecticut. White mildew colonies first appeared in the early summer, 4 to 6 weeks after leaf emergence, and the initial colonies rapidly coalesced to cover the entire adaxial leaf surface. Incidence on observed trees reached nearly 100%. Premature autumn coloration and defoliation occurred on those trees where incidence was highest; tree mortality due solely to powdery mildew was not observed. Cleistothecia were apparent on both adaxial and abaxial leaf surfaces within 4 to 6 weeks of initial infection. Mycelium was white in color, and conidiophores were three-celled with a slightly bent foot cell. Fibrosin bodies were not present in conidia (n = 400), which measured 14.1 m ± 0.80 × 28.1 m ± 1.60 (mean + standard error of the mean). Cleistothecia measured 114.7 m ± 1.77 in diameter, and had 4 to 10 dichotomously branched appendages, which measured 140.7 m ± 3.95 in length (1.23× cleistothecial diameter). The fungus was identified as Microsphaera pulchra based on mycelial, conidial, and cleistothecial characteristics (1). In addition, cleistothecia were found on twigs and on fallen leaves of dogwood; these overwintering cleistothecia contained mature asci and mature ascospores in March 1999. Microsphaera penicillata recently was redescribed to include only that species causing powdery mildew on Alnus spp., and having appendages 1.5× cleistothecial diameter (2). The fungus causing powdery mildew in Connecticut previously had been reported to be M. penicillata, which was not found in the present study. References: (1) U. Braun. Nova Hedwigia 89:1, 1987. (2) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer, New York, 1995.
First Report of Alternaria tenuissima as a Leaf Pathogen of Amaranthus hybridus
Authors: Blodgett J. T. , Swart W. J. , Chen Weiqun 
Published: May 2007

Amaranthus hybridus is an important alternative leafy-vegetable crop with the potential for increased commercial production in southern Africa and other semi-arid regions of the world (2). In May 1998, extensive leaf spotting was observed on A. hybridus at Potchefstroom, South Africa. Many of the leaves had symptoms and most were severe. Symptoms were dark brown to black, circular to oval, necrotic lesions with a diameter ranging from <1 mm up to 7 mm. Larger lesions had tan centers. Tissues adjacent to the leaf spots remained green. Alternaria tenuissima was isolated from 43% of 40 lesions sampled making up 89% of the isolates recovered. A. tenuissima was isolated from asymptomatic leaves of 5-month-old A. hybridus plants sampled from the same site in April 1997 (1). The foliar symptoms observed on A. hybridus in Potchefstroom were reproduced by inoculating wounded leaves of A. hybridus with single-spore A. tenuissima isolates obtained from asymptomatic leaves collected at Potchefstroom. Eight isolates were selected for pathogenicity tests conducted in a growth chamber. A. hybridus leaves grown from seed in a greenhouse were placed in moist chambers and wounded with a needle (0.5 mm) at leaf center; one 5-mm-diameter, colonized potato dextrose agar plug of each of the isolates was placed on the center of each leaf. A sterile plug was used as a control. Moist chambers were placed in a growth chamber set at 25°C day and 20°C night and provided artificial light for 16 h per day. In a greenhouse (average temperature 25°C day, 17°C night), a conidial suspension (105 conidia per ml of sterile, distilled water) was applied to an individual leaf of each of 14 plants with an atomizer. Sterile, distilled water was applied to control leaves. Leaves were then wounded with a needle (0.5 mm) at leaf center. Treatments were assigned randomly and the experiments were repeated. Symptoms were first observed at 14 and 18 days (growth chamber and greenhouse, respectively). Seven of the eight isolates caused necrotic lesions with an average diameter of 3 mm (both growth chamber and greenhouse). Symptoms were observed on an average of 56 and 82% of the inoculated leaves (growth chamber and greenhouse, respectively). The range of symptoms was the same as that observed in the field, but symptoms were only observed at the wounds. Controls remained green and showed no symptoms. A. tenuissima was recovered from necrotic lesions of surface-disinfested, inoculated leaves (average 93 and 68%; growth chamber and greenhouse, respectively), never recovered from growth chamber controls, and seldom recovered from greenhouse controls (5%). These results suggest that A. tenuissima is a leaf-spot pathogen of A. hybridus and wounding might trigger disease expression. A minimal amount of leaf spotting of this leafy-vegetable crop can cause total crop loss. References: (1) J. T. Blodgett et al. S. Afr. J. Sci. 94:xviii, 1998. (2) W. J. Swart et al. S. Afr. J. Sci. 93:xxii, 1997.
First Report of Ceratocystis fimbriata Infecting Balsam Poplar (Populus balsamifera)
Authors: Vujanovic Vladimir , St.-Arnaud Marc , Charlebois Denis , Fortin Elisabeth 
Published: May 2007

This is the first report of Ceratocystis fimbriata Ellis & Halst. (Ophiostomatales) (anamorph: Chalara sp. (Corda) Rabenh.) associated with symptoms of perennial canker on small branches and wilt of leaves and twigs on balsam poplar (Populus balsamifera L.). The fungus is known to occur on trembling aspen (P. tremuloides Michx.) (1) throughout the mountainous West and extends eastward to Quebec and Pennsylvania (2).These tree species are common in the boreal and Rocky Mountain areas of North America. In April 1999, the disease was observed on cuttings (15 × 1 cm) collected from the terminal branches of young balsam poplar trees (h = 4.5 m) near Baie Comeau located 350 km northeast of Quebec City (48°61′, 68°21′), Quebec, Canada. Apparently healthy cuttings were potted in a soil mix (peat moss and vermiculite, 3:1 vol:vol), grown in a greenhouse at 22 ± 1°C and watered twice a week. About 2 weeks after bud break, a number of cuttings were symptomatic, showing necrotic bark lesions and cankers, discoloration and wilting of leaves, and reddish brown exudate surrounding leaf petioles. During the following two weeks, 22% of the cuttings died (212 out of 958). The fungus was isolated from diseased cuttings on 2% MEA (malt extract agar), from the necrotic bark around active cankers (2 × 1 cm), from brown to black streaks found in vascular tissue, and from the ascomata found on the canker margin and inconspicuous necrotic roots. From necrotic petioles, one other opportunistic fungus, Aureobasidium pullulans (de Bary) G. Arnaud, was occasionally isolated. The inoculum for infection of the balsam poplar may have originated from neighboring trembling aspen trees. We believe that C. fimbriata could have a negative impact on reforestation efforts unless phytosanitary inspections are made of the planting stock. References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN. (2) W. A. Sinclair et al. 1993. Diseases of Trees and Shrubs. 3rd ed. Cornell University Press, Ithaca, NY.
First Record of Bursaphelenchus Nematodes from Pine Forests in Greece
Authors: Skarmoutsos G. , Skarmoutsou H. 
Published: May 2007

Pine forests are important elements of natural ecosystems in Greece. Pines are very well adapted to the ecoclimatic conditions of this country and are extensively used in plantations. While there is danger of accidental introduction of Bursaphelenchus xylophilus into Europe through timber trade, in recent years pine wilting of unknown cause has been observed in many European countries. In many cases various Bursaphelenchus spp. have been isolated from wilting conifer species (1–3). A survey for nematodes of pine in Greece was carried out from 1996 to 1998, as part of a project (FAIR 1CT 95-0083) funded by the European Commission, in which five European countries are involved. Trees chosen for sampling were either dying or recently dead. From each tree, three disks 10 cm in thickness were cut, from the lower, medium, and upper parts of the main stem. The bark was removed and Baermann-funnel-extraction for nematodes was immediately carried out for 48 h at room temperature. During the 3 years of the survey, samples from 93 pine trees from different areas of Greece were examined. Samples were obtained from the indigenous species Pinus brutia, P. halepensis, P. nigra, and P. sylvestris as well as the exotic species P. pinaster and P. radiata. Thirty-two of the samples were found infected by different species of Bursaphelenchus. B. eggersi Ruhm was isolated from P. pinaster, B. hellenicus Skarmoutsos, Braasch, and Michalopoulou from P. brutia, and B. leoni Baujard from P. brutia, P. nigra, P. pinaster, and P. radiata. B. sex-dentati Ruhm, the most abundant of all species, was recovered from P. brutia, P. halepensis, P. nigra, P. pinaster, and P. radiata, whereas B. teratospicularis Kakuliya was isolated from P. brutia and P. halepensis. Samples from P. sylvestris did not yield any Bursaphelenchus nematodes. All isolated species constitute a first record in Greece with B. hellenicus described as a new species (4). This study on the relationship between dead and dying pines and nematodes of the genus Bursaphelenchus is the first undertaken in this country. References: (1) P. Baujard. Rev. Nématol. 3:167, 1980. (2) A. Marinari Palmisano and L. Ambrogioni. Redia 77:225, 1994. (3) J. Philis and H. Braasch. Nematol. Mediterr. 24:119, 1996. (4) G. Skarmoutsos et al. Nematologica 44:623, 1998.