bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of the Bemisia tabaci B Biotype in India and an Associated Tomato leaf curl virus Disease Epidemic
Authors: Banks G. K. , Colvin J. , Reddy R. V. Chowda , Maruthi M. N. , Muniyappa V. , Venkatesh H. M. , Kumar M. Kiran , Padmaja A. S. , Beitia F. J. , Seal S. E. 
Published: May 2007

In May 1999, in the Kolar district of Karnataka State, Bemisia tabaci numbers on tomato increased by approximately 1,000-fold that observed previously (3). This was associated with an epidemic of severe tomato leaf curl disease that caused complete crop failure. DNAs extracted from 35 symptomatic tomato leaf samples collected within the epidemic region all gave the expected 500 to 600 bp amplicon with begomovirus-specific primers A/B (1). These primers amplify from the conserved nonanucleotide TAATATTAC in the common region of DNA-A to the conserved amino acid sequence CEGPCKYG within the coat protein gene. AluI and TaqI restriction patterns of all 35 polymerase chain reaction (PCR) products were identical. One PCR product from an epidemic (GenBank no. AF321929) and a non-epidemic (AF321930) site (Bangalore) were cloned and sequenced. The two 531-bp inserts showed 96% nucleotide identity to each other and 94% nucleotide identity to the equivalent region of Tomato leaf curl Bangalore virus (ToLCBV-Ban-4) (AF165098), suggesting that the epidemic was caused by an indigenous ToLCBV strain. Adult B. tabaci were collected from tomato plants at nine sites within the epidemic. DNA was extracted from 9 to 13 individuals per site and analyzed by RAPD-PCR using primers OpB20 and OpB11. Eighty to 100% of individuals per site had identical patterns to those of B biotype individuals from Israel and Florida, which were different to the patterns produced by the indigenous Indian B. tabaci. Adult B. tabaci from the epidemic and nonepidemic (Bangalore) regions were cultured separately on zucchini plants (n = 20) vars. Fordhook and Ambassador. Distinct silverleaf symptoms appeared in all plants fed on by the epidemic B. tabaci, but not on those fed on by the nonepidemic whiteflies. Irregular ripening of tomatoes was also a widespread problem in the epidemic area. Cytochrome oxidase I (COI) (720 bp) gene sequences were obtained for epidemic (AF321927) and nonepidemic (AF321928) B. tabaci, which had only 80% nucleotide identity to each other. A GenBank BLAST search showed that the former were most similar to B biotype whitefly from Israel (AF164667; 97%) and Texas (AF164675; 99%). The B biotype transmits Indian ToLCBV (2) and its introduction into India is of great concern as it is already associated with a devastating plant-disease epidemic. References: (1) D. Deng et al. Ann. App. Biol. 125:327, 1994. (2) P. F. McGrath and B. D. Harrison. Ann. App. Biol. 126:307, 1995. (3) H. K. Ramappa et al. Ann. App. Biol. 133:187, 1998.
First Report of Phytoplasma Infection in Freesia Plant
Authors: Kamińska M. , Sliwa H. , Startek L. 
Published: May 2007

Disease symptoms including leaf chlorotic and necrotic spots and stripes resembling freesia leaf necrosis (disease of unknown etiology [2]) were observed in freesia (Freesia × hybrida Klatt.) plants (cvs. Aladyn, Blue Lady, Cortine, Gompy, and White Rapid) naturally infected with Freesia mosaic virus (FMV) and grown in the greenhouse in Poland. The aim of this work was to study the association of the leaf symptoms occurring in freesia cultivars with phytoplasma infection and to identify it. To detect the possible presence of phytoplasmas in freesias, plants showing leaf symptoms (five cultivars) and symptomless plants (‘Blue Lady’, ‘Cortine’, and ‘Gompy’) were assayed for the presence of phytoplasma 16S rDNA fragment by polymerase chain reaction (PCR). For phytoplasma detection samples of young leaves and corms of 15 symptomatic and five symptomless freesias were taken. The samples were collected from the selected plants infected with FMV. In addition, leaf samples from healthy Catharanthus roseus plants and those infected with AKV reference strain of aster yellows (AY) phytoplasma group, subgroup I-B (supplied by W. Jarausch, INRA Bordeaux, France), were included for comparison. The amplification was performed using the universal—rA/fA or R16F1/R0 and group specific—R16(I)F1/R1 phytoplasma primer pairs (1). Phytoplasma identification was accompanied by digestion with AluI and MseI restriction endonucleases and restriction length polymorphism (RFLP) analysis of the R(I)F1/R1 or rA/fA products. DNA amplification product was observed in all nested PCRs containing template DNA derived from the leaves and corms of all symptomatic as well as symptomless and FMV-affected freesias except symptomless freesia ‘Cortine’. Based on RFLP analysis of PCR products and the comparison of the RFLP patterns with those of the strain AKV of aster yellows phytoplasma group (AY I-B), the associated phytoplasmas were identified as phytoplasma 16S rRNA group I, subgroup B. This work provides the first evidence that freesias examined were naturally infected with aster yellows phytoplasma. Detection of phytoplasma in diseased and symptomless but FMV-affected freesias underlines the need to know the role of this pathogen in the etiology of freesia diseases. References: (1) I.-M. Lee et al. Phytopathology 84:559, 1994. (2) H. J. M van Dorst. Neth. J. Plant Pathol. 79:130, 1973.
First Report of a Furovirus Infecting Field-Grown Rye in North America
Authors: Momol M. T. , Blount A. , Kucharek T. A. , Petersen M. A. , Nielsen M. , Dankers W. , Barnett R. D. 
Published: May 2007

Viral symptoms were present in a dwarf recurrent population (99RP17) of rye (Secale cereale) at the North Florida Research and Education Center in Quincy, Gadsden County, FL, during the winter and spring of 2000. Symptoms and distribution of the infected plants in the field were similar to those caused by Soilborne wheat mosaic virus (SBWMV; acronym WSBMV), which was first recognized in North America in 1919 (4) and found in Florida in wheat in 1970 (3). SBWMV has been observed based on symptoms in rye in North America (4). Interveinal, non-continuous, chlorotic areas of leaves and stunting of plants in patchy patterns occurred in four locations (0.8 to 1.6 km between locations). Incidences of the disease ranged from 3 to 15%. Leaves and roots of more than 25 plants were assessed. Using light microscopy, after staining with Calcomine Orange 2RS/Luxol Brilliant Green BL (1), amorphous, vacuolate inclusions were observed in all assayed leaves. With electron microscopy, rigid rods were present with a bimodal distribution of particle lengths that conformed to size distributions found originally in wheat in 1970 in Florida. Leaves with symptoms were sent to Agdia Inc. (Elkhart, IN) and samples were strongly positive for SBWMV using enzyme-linked immunosorbent assay. Cystosori of Polymyxa graminis were detected from a few roots from symptomatic plants. While these associations are suggestive of SBWMV, and rye is a reported host of SBWMV, the possibility of this virus being soilborne rye mosaic virus exists (2). Such a differentiation will require nucleotide sequence analysis. To our knowledge, this is the first report of a furovirus infecting field-grown rye in Florida and in North America. References: (1) R. G. Christie and J. R. Edwardson. 1994. Light and Electron Microscopy of Plant Virus Inclusions Monogr. 9. University of Florida, Quincy. (2) R. Koenig et al. 1999. Arch. Virol. 144:2125–2140. (3) T. A. Kucharek and J. H. Walker. Plant Dis. Rep. 58:763–765, 1974. (4) H. H. McKinney. J. Agric. Res. 23:771–800, 1923.
First Report of Fusarium oxysporum f. sp. lycopersici Race 3 on Tomato in Tennessee
Authors: Bost S. C. 
Published: May 2007

In the summer of 2000, tomato (Lycopersicon esculentum Mill.) plants in several commercial fields in southeastern and eastern Tennessee exhibited symptoms of Fusarium wilt. All cultivars on which symptoms were observed are classified as resistant to races 1 and 2 of the causal fungus, Fusarium oxysporum Schlechtend.:Fr. f. sp. lycopersici (Sacc.) W.C. Snyder and H.N. Hansen. Race 3 has been reported from several areas (1), but not from Tennessee, a major producer of fresh market tomatoes. F. oxysporum was consistently isolated from discolored vascular tissue on potato dextrose agar (PDA). Pathogenicity and race determination tests for six isolates representing three counties were conducted by inoculating cultivars susceptible to races 1, 2, and 3 (Rutgers); resistant to race 1 (Bradley, Roma VF); resistant to races 1 and 2 (Conquest, Florida 47); or resistant to races 1, 2, and 3 (Floralina). Inoculum suspensions were obtained from 1-week-old cultures grown on PDA. Seedlings were grown in commercial potting mix for 3 weeks. The roots were rinsed and submerged for 30 s in inoculum suspensions (1 × 107 conidia per ml). Seedlings were then transplanted into potting mix in metal flats and placed in a greenhouse. Natural light conditions provided a 12-h photoperiod, and day and night temperatures averaged 29 and 17°C, respectively. Within 4 weeks after inoculation, all isolates caused symptoms of Fusarium wilt in all cultivars except Floralina, indicating that the isolates were race 3. The pathogen was reisolated from the discolored vascular tissue of diseased plants. Among the cultivars most severely affected by all six isolates was Conquest, which is resistant to F. oxysporum f. sp. radicis-lycopersici, the cause of Fusarium crown and root rot. Reference: (1) M. L. Marlatt et al. Plant Dis. 80:1336, 1996.
First Report of Sugarcane yellow leaf virus (ScYLV) in Costa Rica
Authors: Avila R. , Arrieta M. C. , Villalobos W. , Moireira L. , Chavarría E. , Lockhart B. E. L. , Rivera C. 
Published: May 2007

In Costa Rica, sugarcane plants with symptoms similar to those described for yellow leaf syndrome (YLS) (1,2) were first observed in 1994 in research plots of imported material in the midland areas of San Carlos and Turrialba. Recently, the same symptoms have been observed in commercial plantations in Turrialba. Symptomatic plants were characterized by yellowing of the leaves and central veins, the yellowing being more intense near the leaf tips. In severe cases, veins became reddish, and necrosis developed along the leaf edges, beginning at the leaf tip and extending to the base of the leaf. Growth of stems and roots was also reduced in infected plants. Minipurifications of six plants of four different varieties were examined by immunospecific electron microscopy (ISEM) using polyclonal antibodies (1). They were: one symptomatic plant each of the varieties H782313 and H608521; two symptomatic plants of H657052, and one asymptomatic plant each of H608521 and H827318. Isometric particles of approximately 28 nm were observed in the asymptomatic H827318 plant and in all symptomatic plants, with the exception of one plant of H657052. The size and morphology of the particles was similar to those reported for Sugarcane yellow leaf virus (ScYLV) (2). The presence of ScYLV was verified by indirect enzyme-linked immunosorbent assay (ELISA) using polyclonal antibodies (1). Twenty-two of 24 symptomatic plants and five of 13 asymptomatic plants were positive for ScYLV. These findings confirm the association of ScYLV with the yellows syndrome of sugarcane observed in Costa Rica. However, as was also reported by Scaglusi and Lockhart (1), ScYLV was not detected in several symptomatic plants, and research is continuing to determine whether other pathogens are associated with this syndrome in Costa Rica. References: (1) S. Scagliusi and B. E. L. Lockhart. Phytopathology 90:120, 2000; (2) J. Vega et al. Plant Dis. 81:21, 1997.
First Report and Characterization of Rice yellow mottle virus in Central Africa
Authors: Traoré O. , Pinel A. , Fargette D. , Konaté G. 
Published: May 2007

Rice yellow mottle virus (RYMV) of the genus Sobemovirus is the main virus infecting rice (Oryza sativa) in Africa. First reported in Kenya (East Africa), RYMV was later found in most countries of East and West Africa where rice is grown, and in Madagascar in the Indian Ocean. In Central Africa however, the disease had never been reported in rice fields. Ninety-eight field samples with typical yellow mottle symptoms from cultivated rice and two wild rice species (Oryza longistaminata and O. barthii) were collected in the Soudano-Sahelian zones, in the north of Cameroon and the south of Chad (Central Africa) in September 2000. RYMV was detected by ELISA with polyclonal antisera (1) in all samples. All virus isolates were also mechanically transmitted to rice cv. BG 90-2, which is highly susceptible to RYMV. Tests with monoclonal antibodies showed that most isolates from Central Africa were of the SI serotype, which is widespread in the Soudano-Sahelian zones of West Africa (1). The coat protein gene of 7 isolates was amplified by RT-PCR and the expected 720 bp fragment was obtained. Resulting sequences (AJ306735, AJ317949, AJ317950, AJ317951, AJ317952, AJ317953, AJ317954) shared over 95% sequence identity. They were compared to a set of sequences of RYMV isolates from cultivated rice of different geographical origins (2). Phylogenetic analyses by maximum parsimony (PAUP 4) showed that isolates from Central Africa belonged to a monophyletic group, a sister group of West African isolates from the Soudano-Sahelian zones, further supporting the geographic basis of RYMV diversity (2). RYMV incidence was generally less than 10% but reached 20% in some irrigated plots in the two countries. References: (1) G. Konaté et al. Arch Virol. 142:1117, 1997. (2) A. Pinel et al. Arch. Virol. 145:1621, 2000.
Report of Sugarcane yellow leaf virus in Ecuador, Guatemala, and Nicaragua
Authors: Comstock J. C. , Pena M. , Vega J. , Fors A. , Lockhart B. E. L. 
Published: May 2007

In 1998, sugarcane plants with symptoms similar to yellow leaf syndrome were observed in Ecuador, Guatemala, and Nicaragua. These plants showed yellowing of the central portion of the third to sixth leaves on the abaxial surface from the youngest expanding spindle leaf. Intense yellowing and necrosis of the leaf tip and the central portion of the leaf blade near the midrib occurred in severe cases. A tissue blot immunoassay was used to detect Sugarcane yellow leaf virus (SCYLV) in the midrib of the top visible dewlap leaf (2) using an antiserum specific to a Florida isolate of SCYLV (1). Since the virus can be detected in asymptomatic plants, leaf samples were collected from both symptomatic and asymptomatic plants. Symptom expression was most intense in plants at maturity that were under stress. Cut ends of leaf samples were imprinted on nitrocellulose membranes in the country of origin, and control samples of healthy and SCYLV-infected leaves were imprinted in Florida on each membrane prior to serological processing. The results from the following locations and cultivars, and the ratio of SCYLV-positive samples over the total samples is indicated: Milagro, Ecuador, PR 70-2085 (11/24) and PR 76-3385 (48/63) in 1999; Escuintla, Guatemala, CP 57-603 (1/10), CP 73-1547 (0/10), CP 72-2086 (120/308), PR 75-2002 (8/11), PR 78-294 (10/10), and PR 87-2080 (13/13) in both 2000 and 2001; Tipitapa, Nicaragua, L 68-40 (21/70) in 1998; and Chinandega, Nicaragua, CP 72-2086 (30/30) and CP 74-2005 (13/45) in 2000. CP 72-2086 is a major commercial cultivar in Central American countries and was infected in both Guatemala and Nicaragua. SCYLV was detected in 9 of 10 cultivars sampled. An exception was noticed in CP 73-1547 in Guatemala where none of the 10 plants tested were infected; however this cultivar has a high incidence of SCYLV in Florida. Only 1 of 10 samples of CP 57-603 was SCYLV positive in Guatemala; however, this cultivar has a low incidence of infection in Florida and is considered more resistant than the other CP cultivars sampled. To our knowledge, this is the first report SCYLV in Ecuador, Guatemala, and Nicaragua. References: (1) S. M. Scagliusi and B. E. L. Lockhart. Phytopathology 90:120, 2000. (2) S. Schenck et al. Sugar Cane 4:5, 1997.
First Report of Phytophthora ramorum on Douglas-Fir in California
Authors: Davidson J. M. , Garbelotto M. , Koike S. T. , Rizzo D. M. 
Published: May 2007

Phytophthora ramorum S. Werres & A.W.A.M. de Cock was isolated from three Douglas-fir (Pseudotsuga menziesii) saplings in a mixedevergreen forest in Sonoma County, California. Symptoms on these saplings included cankers on small branches (0.5 to 1 cm in diameter) resulting in wilting of new shoots, dieback of branches, and loss of leaves as much as 15 cm from the twig tip. Symptoms were observed on most saplings growing in the same area. On several smaller saplings (<1 m tall), P. ramorum infection resulted in the death of the leader and the top several whorls of branches. Isolates were identified as P. ramorum by their abundant chlamydospores and caducous, semi-papillate sporangia (2) and internal transcribed spacer rDNA sequences identical to those of isolates of P. ramorum from Quercus spp., Lithocarpus densiflorus, and Rhododendron (1,2). To test for pathogenicity, foliage inoculations were conducted on seedlings in two trials by misting 30 leaves per trial (five leaves per seedling plus controls) with sterile distilled water and pinning inoculum plugs, taken from the margin of P. ramorum cultures, to the upper surface of leaves. Inoculation resulted in lesions ranging between 1 and 12 mm long, and P. ramorum was recovered from 47% of inoculated leaves. Symptoms were not restricted to inoculated leaves, and in 26 single-leaf inoculations, lesions 17 to 85 mm long developed on branches (five mm in diameter) adjacent to the inoculated leaf. Isolation success from branch lesions was 50%, despite the fact that such lesions were apparently disjunct from the small 1-mm lesions developing on inoculated leaves. Stems of Douglas-fir seedlings (approximately 1 cm in diameter) were wound inoculated (1) in two trials consisting of 10 inoculated seedlings per trial plus 10 controls. After 6 weeks, lesion lengths in the cambium averaged 38 mm (range 12 to 62 mm), and three seedlings were completely girdled. P. ramorum was recovered from 75% of inoculated stems. Mean lesion lengths on seedlings inoculated with P. ramorum were significantly greater (P < 0.05) in both trials than those of control inoculations (mean 9 mm) based on analysis of variance. We have not observed unusual mortality or disease symptoms on overstory Douglas-fir trees in natural forests. The importance of P. ramorum branch tip dieback for growth and reproduction of Douglas-fir is unknown. Douglas-fir is present in many forests in California and Oregon already infested by P. ramorum, yet we have found infection of plants at only one location. At this site, symptomatic Douglas-fir saplings were surrounded by bay laurel (Umbellularia californica) trees with extremely high levels of P. ramorum infection. P. ramorum is known to sporulate prolifically on bay laurel leaves. More studies are necessary to determine if the incidence of P. ramorum in Douglas-fir extends to other locations or if it is limited to this one locale. References: (1) D. M. Rizzo et al. Plant Disease 86:205, 2002. (2) S. Werres et al. Mycol. Res. 105:1155, 2001.
First Report of Xanthomonas Leaf Blight of Onion in California
Authors: Nunez J. J. , Gilbertson R. L. , Meng X. , Davis R. M. 
Published: May 2007

In 2000 and 2001, severe leaf blight of fresh market onions occurred in several fields in the Antelope Valley of California, a high desert area located in northern Los Angeles County. In at least two fields, 70% of the canopy was affected, which resulted in an estimated yield reduction of over 50%. Both organically and conventionally grown onions were affected. Symptoms included numerous small chlorotic lesions that appeared first on older leaves. Lesions were often surrounded by water-soaked margins. As the season progressed, the lesions became elongated and necrotic. Entire leaf blades were often killed. The disease never progressed into the bulbs, but bulbs of infected plants never grew to full size. Yellow mucoid bacterial colonies were recovered on yeast extractdextrose-CaCO3 agar from symptomatic tissue. All isolates were gram-negative rods with single polar flagella. Two representative isolates were identified as Xanthomonas campestris based on their carbon utilization profile (similarity index of 0.784 and 0.850; Biolog, Hayward, CA), fatty acid profile (similarity index of 0.588; MIS-TSBA, version 4.10, MIDI Inc., Newark, DE), and 16S-23S intergenic spacer DNA sequences (98% sequence identify with strains of X. campestris). In greenhouse pathogenicity tests, eight white globe onion plants were inoculated with a bacterial suspension (106 CFU/ml) of each of the two isolates. Plants were inoculated by spraying the suspension on leaves lightly injured by rubbing with Carborundum or puncturing with needles dipped in the suspension. Controls were inoculated with water. All plants inoculated with the bacteria developed symptoms in 6 days. The bacterium was reisolated from all inoculated plants and confirmed as Xanthomonas. The trial was conducted twice. To our knowledge, this is the first report of Xanthomonas leaf blight of onion in California. In the United States, the disease has been reported in Texas and Colorado (1,2). References: 1. T. Isakeit et al. Plant Dis. 84:201, 2000. 2. H. F. Schwartz and K. Otto. Plant Dis. 84:922, 2000.
Report of Root Rot Caused by Pythium F-Group on Hydroponically Grown Celery in South Africa
Authors: Labuchagne N. , Gull C. , Wehner F. C. , Botha W. J. 
Published: May 2007

Celery (Apium graveolens) is commonly grown in hydroponic systems in South Africa. During the warm summer months, plants often become stunted or die, with mortality as high as 70% in some systems. Affected plants show severe root rot and yellowing of the foliage. Root segments excised from symptomatic celery plants collected from various hydroponic systems in Gauteng Province, South Africa, were rinsed in sterile distilled water and plated on PARP medium (2). Pythium was isolated consistently from both rotted and symptomless roots. Isolates produced only noninflated filamentous sporangia and no oospores, conforming to the description of Pythium F-group (1). Koch's postulates were confirmed by inoculating 4-week-old celery seedlings cultivated in aerated nutrient solution in a hydroculture system in the greenhouse. A zoospore suspension (105 zoospores per ml) of Pythium F-group cultured on V8 juice agar was added to the nutrient solution at the rate of 3 ml/1iter. Control plants received no inoculum, and the experiment was repeated once. Plants were assessed after 4 weeks. All inoculated plants showed symptoms of root rot, stunting, and yellowing, whereas control plants remained healthy. Pythium F-group was recovered on PARP medium only from the roots of inoculated plants. Pythium F-group has been described as a pathogen of celery elsewhere, but to our knowledge, this is the first report of root rot caused by the fungus on celery in South Africa. References: (1) M. W. Dick. Keys to Pythium. University of Reading Press, Reading, UK, 1990. (2) S. N. Jeffers and S. B. Martin. Plant Dis. 70:1038, 1986.