bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of a Natural Infection of Opuntia sp. by a ‘Candidatus Phytoplasma asteris’-Related Phytoplasma in China
Authors: Wei W. , Cai H. , Chen H. , Davis R. E. , Zhao Y. 
Published: May 2007

Cacti (Opuntia spp.) are perennial, evergreen, succulent plants native to arid areas of the Americas. Because of their aesthetic appearance, many cacti have been cultivated and introduced to other parts of the world as ornamentals. Cacti are susceptible to phytoplasma infections and develop witches'-broom (WB) disease. Currently, all reported cactus WB cases are associated with infections by phytoplasmas in the peanut witches'-broom group (16SrII) (1,2,4). During a phytoplasma diversity survey carried out during 2004 in Yunnan, China, we collected 29 malformed and 14 healthy-looking naturally occurring cactus plants from 14 locations representing five geographical regions. Each of the 29 malformed plants exhibited stunted growth and possessed clusters of highly proliferating cladodia, typical symptoms of cactus WB disease. Nested-PCR was carried out on the DNA samples extracted from young cladodia of these plants using phytoplasma-universal 16S rDNA primers P1A/P7A and R16F2n/R16R2 (3). Results revealed that all 29 diseased plants that were examined were infected by phytoplasmas, whereas all 14 healthy-looking plants were negative for phytoplasmas. Subsequent restriction fragment length polymorphism (RFLP) analysis of the PCR-amplified 1.25-kb 16S rDNA fragments indicated that 28 diseased plants were infected by a phytoplasma of group 16SrII, whereas one plant (from Suan Village) was infected by a ‘Candidatus Phytoplasma asteris’-related (group 16SrI) phytoplasma designated as strain YN26. Nucleotide sequence analysis of the strain YN26 partial rRNA operon (GenBank Accession No. EF190970), covering a near full-length 16S rRNA gene, a 16S-23S rRNA intergenic spacer, a tRNA-Ile gene, and a partial 23S rRNA gene, suggested that this phytoplasma is most closely related to an ash witches'-broom phytoplasma (GenBank Accession No. AY566302, 99.7% identity) and an epilobium phyllody phytoplasma (GenBank Accession No. AY101386, 99.7% identity), both members of subgroup16SrI-B. This YN26-infected cactus plant was transferred to a greenhouse and maintained for more than 2 years, during which time DNA samples were extracted and tested two additional times. The same 16S rDNA RFLP pattern type was consistently obtained in these tests, confirming that the plant remained infected by the 16SrI phytoplasma. To our knowledge, this is the first report of a natural infection of a cactus species by a group 16SrI phytoplasma. Since this 16SrI-cactus WB phytoplasma was found in the same geographical location where 16SrII-cactus WB phytoplasma was detected both in this and a previous study (1), the findings raised the question whether 16SrI- and 16SrII-cactus WB phytoplasmas have overlapping geo- and bioecological niches. References: (1) H. Cai et al. Plant Pathol. 51:394, 2002. (2) E. Choueiri et al. Plant Dis. 89:1129, 2005. (3) I. M. Lee et al. Int. J. Syst. Evol. Microbiol 54:337, 2004. (4) N. Leyva-Lopez et al. Phytopathology (Abstr.) 89(suppl):S45, 1999.
First Detection of Grapevine leafroll associated virus-7 in California Vineyards
Authors: Morales R. Z. , Monis J. 
Published: May 2007

Grapevine leafroll is one of the most important viral diseases in grapevine and occurs wherever grapevines are grown. At least nine different Grapevine leafroll associated viruses (GLRaVs) belonging to different genera within the Closteroviridae family have been reported. Typical leafroll symptoms include downward rolling and interveinal reddening or yellowing of leaves, reduced fruit size, sugar content, and yield. Our laboratory has detected the presence of GLRaV-7 in many grapevine cuttings collected in California vineyards. During the 2005-2006 fall/winter testing season, symptomatic and asymptomatic grapevine varieties collected from different vineyards in California were tested for the detection of economically important viruses and processed for reverse transcription (RT)-PCR and ELISA. The RT-PCR assays using primers specifically designed for the detection of GLRaV-7 (C. Turturo et al., 13th ICVG [Abstr.], 2000) amplified a single band of approximately 200 bp in samples from selections of Chardonnay, Merlot, Pinot Noir, and Sauvignon Blanc cultivars. The same samples showed low or no reactivity to GLRaV-7 specific antibodies (BIOREBA AG, Reinach, Switzerland). The variability of detection by ELISA can be due to the lower sensitivity of ELISA as compared with RT-PCR and the uneven distribution of GLRaVs in grapevines (1). To confirm that the amplified DNA was GLRaV-7 specific, different isolates were sequenced and compared with the nucleotide and derived amino acid sequences obtained by Turturo et al. (13th ICVG [Abstr.], 2000). The California isolates showed 81 to 98% similarity with the Italian isolates. To our knowledge, this is the first report of GLRaV-7 in California and the United States. Our initial testing data indicates that GLRaV-7 is wide spread in California vineyards. Further studies will allow us to determine the potential effect of this virus in grapevines grown in California. Reference: (1) J. Monis, and R. K. Bestwick. Am. J. Enol. Vitic. 47:199, 1996.
First Occurrence of Anthracnose Caused by Colletotrichum gloeosporioides on Pitahaya
Authors: Palmateer A. J. , Ploetz R. C. , van Santen E. , Correll J. C. 
Published: May 2007

Pitahaya, Hylocereus undatus Britt. & Rose, is a columnar, climbing cactus that produces a commercially important fruit. In December 2004, a new disease was found on the crop in Miami-Dade County, FL. Reddish brown lesions with conspicuous chlorotic haloes developed concentrically on the edges of vine ribs. Lesion centers became white and coalesced to rot much of the vine column, and in severe cases, only the vascular column in the vine center was not diseased. Salmon-colored spores and waxy, subepidermal acervuli, typically with setae and simple, short, erect conidiophores, were observed in lesion centers. Tissue from lesion margins was surface disinfested and plated on potato dextrose agar (PDA; Difco Laboratories, Detroit, MI). Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. was isolated from all samples. Colonies produced abundant conidia that were hyaline, one celled, straight, cylindrical, and averaged 14.7 × 5.0 μm with ranges of 12.5 to 17.5 × 3.8 to 7.5 μm (1). Cultural and morphological characteristics of isolates matched those for C. gloeosporioides except for appressoria and hyphopodia (1,2); pitahaya isolates had a spherical rather than lobed hyphopodia reported for C. gloeosporioides and averaged 10.9 (8.5 to 12.7) × 9.1 (7.1 to 10.3) μm. Internal transcribed spacer sequences for the pitahaya isolates were nearly identical (98% homology) to those for C. gloeosporioides isolates occurring on Euphatorium thymifolia in Thailand (GenBank Accession No. AY266393). Koch's postulates were examined in greenhouse trials at the Tropical Research and Education Center, Homestead, FL. Treatments consisted of a noninoculated control, four C. gloeosporioides isolates, and an Alternaria sp. All isolates came from symptomatic pitahaya tissue collected in Miami-Dade County. Fungi were grown on PDA for 7 days at 27°C. A sterile dissecting needle was used to gently pinprick the epidermis of the stem and 2-mm-diameter plugs of C. gloeosporioides, an Alternaria sp., or clean PDA were placed over wounds. Plants were placed in a plastic tent in a greenhouse where the temperature was held at 25°C, and free moisture was maintained on plant surfaces with a household humidifier for 48 h following inoculation. Two isolates of C. gloeosporioides were shown, in repeated greenhouse experiments, to cause reddish brown lesions with conspicuous chlorotic haloes that coalesced to rot much of the vine column, and Koch's postulates were completed with the reisolation of isolates that were used to inoculate plants. The age of vine segments had no significant effect on lesion development. To our knowledge, this is the first report of C. gloeosporioides as a pathogen of pitahaya. References: (1) J. A. Bailey and M. J. Jeger. Colletotrichum: Biology, Pathology and Control. CAB International, Wallingford, UK, 1992. (2) M. Du et al. Mycologia 97:641, 2005.
Phytophthora Species in Soils Associated with Declining and Nondeclining Oaks in Missouri Forests
Authors: Schwingle B. W. , Juzwik J. , Eggers J. , Moltzan B. 
Published: May 2007

Periodic episodes of oak decline have occurred in the Missouri Ozark forests since the early 1900s and the disease is currently severe (2). Several Phytophthora spp. contribute to oak decline in Europe (1), but the role of Phytophthora spp. in oak decline in the eastern United States is not known. Mineral soils collected around the bases of declining and nondeclining oaks in paired sites in central Missouri forests were assayed for the presence of these taxa by baiting flooded soil with Quercus robur leaves. Q. rubra and Q. velutina were the oak species on three sites and Q. alba was on the fourth. Isolates from symptomatic baits plated on PARPNH selective medium were identified tentatively on classical taxonomic characteristics. Five isolates of P. cambivora, two of P. quercina, and eight of P. cinnamomi were obtained from soils around one, one, and three trees, respectively, on decline sites. The internal transcribed spacer sequences for each isolate were compared to those in GenBank; BLAST searches for all isolates had nucleotide identities of 99% and E values of 0, which confirmed the identifications. Greenhouse pot trials were conducted to assess pathogenicity of isolates on stems of 2-year-old Q. alba and Q. rubra. A mycelial agar plug was inserted into a 1-cm long slit cut into the cambium 5 cm above the root collar and covered with sterile, moist cotton and wrapped with laboratory film. The treatments included two isolates of P. cambivora, one of P. quercina, three of P. cinnamomi, and a sterile agar plug. Each host × isolate combination was replicated four times, and the experiment was conducted twice in the greenhouse (natural lighting; temperature ≤32°C in summer and ≥7°C in winter). Stem lesions were produced commonly by P. cambivora (28 of 32 seedlings) and P. cinnamomi (46 of 48 seedlings) within 3 months; none was found on control seedlings or those inoculated with P. quercina. Mean lengths (cm) of lesions caused by P. cinnamomi were greater for Q. rubra (5.6) than for Q. alba (4.3) and lesion lengths for P. cambivora were greater for Q. alba (5.2) than for Q. rubra (4.4). Seven Q. alba seedlings inoculated with P. cambivora and one Q. alba inoculated with P. cinnamomi died before 3 months. All Phytophthora species were recovered from inoculated stems at 3 months except that P. quercina was not recovered in one trial. To our knowledge, this is the first report of Phytophthora species in soils of Missouri oak forests, of P. quercina in the United States, and of the ability of P. cambivora to cause stem lesions on Q. alba. P. cinnamomi and P. cambivora should be investigated in situ as possible contributing factors of oak decline in Missouri. References: (1) T. Jung et al. Plant Pathol. 49:706, 2000. (2) R. Lawrence et al. MO. Conserv. 63:11, 2002.
First Report of Powdery Mildew Caused by Golovinomyces orontii (Erysiphe orontii) on Lamium galeobdolon in Italy
Authors: Garibaldi A. , Bertetti D. , Minerdi D. , Gullino M. L. 
Published: May 2007

Lamium galeobdolon L. (Labiatae) is a common ornamental species that grows in shade areas and often used as a ground cover in gardens. During the summer of 2006, severe outbreaks of a previously unknown powdery mildew were observed on all Lamium spp. plants in some gardens near Biella (northern Italy). Both surfaces of the leaves of affected plants were covered with dense, white mycelia and conidia. As the disease progressed, infected leaves turned yellow and died. Mycelia and conidia also were observed on stems and flowers. Conidia were hyaline, ellipsoid, borne in short chains (with a maximum of five conidia per chain), and measured 29 to 37 × 16 to 20 μm (average 33 × 18 μm). Conidiophores, 91 to 104 μm (average 96 μm) long, showed the foot cell measuring 28 to 49 × 9 to 11 μm (average 38 × 10 μm), followed by three shorter cells measuring 14 to 26 × 9 to 15 μm (average 21 × 11 μm). Fibrosin bodies were absent. Chasmothecia were not observed in the collected samples. The internal transcribed spacer region (ITS) of rDNA was amplified using the primers ITS4/ITS6 (4) and sequenced. BLASTn analysis (1) of the 436 bp obtained showed an E-value of 0.0 with Golovinomyces orontii (Erysiphe orontii.) (3). The nucleotide sequence has been assigned GenBank Accession No. EF 121871. Inoculations were made by gently pressing diseased leaves onto leaves of five healthy L. galeobdolon plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a greenhouse at temperatures between 15 and 28°C. After 10 days, typical powdery mildew colonies developed on inoculated plants. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of the presence of powdery mildew on L. galeobdolon caused by G. orontii in Italy. Blumer (2) was able to reproduce powdery mildew symptoms on L. galeobdolon using populations from cucumber, while Braun (3) reported L. galeobdolon as a possible host of E. orontii. Herbarium specimens of this disease are available at AGROINNOVA Collection, University of Torino, Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) S. Blumer. Ber. Schweiz. Bot. Ges. 62:384, 1952. (3) U. Braun. A Monograph of the Erysiphaceae (Powdery Mildews). Cramer, Berlin, GDR, 1987. (4) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997.
First Report of the Foliar Nematode Aphelenchoides ritzemabosi Infecting Chrysanthemum in Iran
Authors: Deimi A. Mohammad , Barouti S. , Rius J. E. Palomares , Castillo P. 
Published: May 2007

During a nematode survey on cut flowers in the Pakdasht Region, Tehran Province, Iran, a species of foliar nematode belonging to the genus Aphelenchoides Fischer was detected in leaves of 10- to 11-month-old, greenhouse-grown (26 to 28°C) chrysanthemum (Dendranthema grandiflorum Kitam., cv. Puja) plants. Chrysanthemum leaves appeared discolored and slightly deformed. Diseased plants comprised approximately 40% of all plants in the greenhouse and occurred in scattered clumps along irrigation paths. Spots and blackish brown, irregular, necrotic areas occupied 5 to 50% of the leaf surface. Symptomatic tissue contained females, males, juveniles, and embryonated eggs of the nematode. All life stages of the nematode were detected in the mesophyll of younger and older infected leaves. The nematode population was extracted and quantified from symptomatic samples of 5 g of leaf tissues by modified Baermann funnel extraction and from 250 g of soil with a modification of the sugar centrifugal flotation method (1), counted, and identified. Morphological observations showed four incisures in the lateral field, excretory pore posterior to nerve ring, ovary single with oocytes in multiple rows, post-vulval uterine sac extending more than one-half of the vulva-anus distance, often containing sperm, tail elongate-conoid bearing a terminal peg with 2 to 4 minute processes. Males common (40% of females) posteriorly curved through 180° upon relaxation, tail conoid bearing a terminal peg with 2 to 3 processes. Measurements of 14 females and 11 males (body length = 987 ± 48 μm, a = 49.2 ± 4.4, b = 12.3 ± 1.1, c = 20.6 ± 2.8, V = 71 ± 1.7, T = 49 ± 2.3, stylet length = 12.6 ± 0.6 μm, tail length = 47.9 ± 5.2 μm; position of vulva = 70.8 ± 1.7%; spicules length = 22.8 ± 1.4 μm) conformed to the description of the chrysanthemum foliar nematode Aphelenchoides ritzemabosi (Schwartz) Steiner & Buhrer, (2). Voucher specimens have been deposited in the University of California Davis Collection. An average of 1,064 A. ritzemabosi per gram were found in the leaves of chrysanthemum, while only 48 nematodes were detected in the soil. To our knowledge, this is the first report of A. ritzemabosi infecting chrysanthemum plants in Iran. References: (1) W. A. Coolen. Page 317 in: Root-Knot Nematodes (Meloidogyne Species) Systematics, Biology, and Control. F. Lamberti and C. E. Taylor, eds., Academic Press, New York, 1979. (2) N. Vovlas et al. Nematology 7:301, 2005.
First Report of Rust Caused by Tranzschelia discolor on Peach in Oman
Authors: Deadman M. L. , Al Maqbali Y. , Al Subhi A. , Al Yahyai R. , Al Sa'di A. , Aime M. C. 
Published: May 2007

Peach (Prunus persica L.) is the primary fruit crop in parts of the northern mountainous regions of Oman. Local cultivars, propagated by seedling, are used to produce fruit for local markets and shade fodder crops planted underneath the peach canopy. In February of 2006, leaf samples showing rust signs and symptoms were collected from Balad Seet, 120 km southwest of Muscat. Angular, yellow spots were observed on leaf upper surfaces with orange sori on the undersides. The disease was observed to be affecting almost 100% of trees, with many leaves having more than 10 sori per leaf. Lesions producing urediniospores were also observed on twigs where spring growth had cracked. Urediniospores typical of Tranzschelia discolor (Fuckel) Tranzschel & M.A. Litv. were obovoid, echinulate, orange-brown, and measured on average 13 to 17 × 26 to 37 μm, with the cell wall 1.3 to 1.8 μm thick at the sides and as much as 5.8 μm thick at the apex. Golden capitate paraphyses were also present, measuring on average 35 to 57 μm long, head 13 to 16 μm in diameter, and tail 4.9 to 6.7 μm wide. Teliospores were not observed because of the time of year of collection. Pathogen identity was confirmed by analysis of a nuclear rDNA sequence spanning from the 5.8S through the ITS-2 into the first 1,000 bp of the 28S gene (1). A voucher specimen was deposited in the U.S. National Fungus Collection (BPI 875341). The voucher's rDNA sequence deposited in GenBank (Accession No. DQ995341) shared 100% sequence similarity with T. discolor (Accession No. DQ354542). Although T. discolor has a worldwide distribution (2), it has not previously been reported from Oman. Improving the quality of peach production in Oman is an agricultural priority because it boosts the economy of smallscale farms in the mountainous regions. This work will facilitate the current research aimed at evaluating cultivar response to rust disease. References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) P. F. Bertrand. Rust. Page 23 in: Compendium of Stone Fruit Diseases. J. M. Ogawa et al., eds. The American Phytopathological Society, St Paul, MN, 1995.
Fusarium Wilt of Gerbera in Spain in Soilless Crops
Authors: Garibaldi A. , Minuto A. , Prados-Ligero A. M. , Melero-Vara J. M. , Gullino M. L. 
Published: May 2007

In 2004, gerbera (Gerbera jamesonii cv. Excellence) plants, grown for cut flowers, were observed in a soilless cultivation system (coconut fiber substrate) in one farm in the Cadiz area (southwestern Spain) exhibiting symptoms of a wilt disease. Gerbera represents a relevant crop for the industry in the region, after rose and carnation. Affected plants were stunted and developed yellow leaves with initially brown and eventually black streaks in the vascular system. The vascular streaks in the yellow leaves were continuous with a brown discoloration in the vascular system of the crown and upper taproot. In some cases, the leaves of affected plants turned red. Fusarium spp. was consistently and readily isolated from symptomatic vascular tissue of infected plants onto a Fusarium-selective medium (3). Colonies were identified as F. oxysporum after subculturing on potato dextrose agar on the basis of morphological observations. Pathogenicity tests were carried out by using two monoconidial isolates, compared with an Italian one, obtained from wilted gerbera plants. Each isolate of F. oxysporum was grown in shake culture (90 rpm) for 10 days on casein hydrolysate at 25°C with 12 h of fluorescent light per day. Healthy rooted 30-day-old plants (cv. Jaska), were inoculated by dipping roots into a conidial suspension (5 × 107 conidia/ml) in one of the three test isolates of F. oxysporum. Plants were transplanted (1 plant per pot) into pots (3.5 liter vol.) containing rockwool-based substrate. Noninoculated plants served as control treatments. Plants (15 per treatment) were grown in a glasshouse at an average day temperature of 30°C and night temperature of 24°C (minimum of 22°C and maximum of 41°C). Wilt symptoms and vascular discoloration in the roots, crown, and veins developed within 30 days on each inoculated plant, while noninoculated plants remained healthy. F. oxysporum was consistently reisolated from infected plants. The pathogenicity test was conducted twice. A wilt of gerbera was described in the Netherlands in 1952 (1) but its presence was not confirmed in further observations (4). Gerbera wilt was recently reported in Italy (2) and identified as F. oxysporum f. sp. chrysanthemi (A. Garibaldi, personal communication). Currently, the wilt of gerbera in Spain is limited to a few farms and a very limited percent (2 to 3%) of plants. References: (1) J. Arx and J. A. von Tijdschr. PlZiekt. 58:5, 1952. (2) A. Garibaldi et al. Plant Dis. 88:311, 2004. (3) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (4) G. Scholten. Neth. J. Plant Pathol. 76:212, 1970.
Sensitivity of Venturia inaequalis Isolates to Fungicides Used in Lebanon
Authors: Al-Arab H. G. Diab , Abou-Jawdah Y. 
Published: May 2007

Apple scab, caused by Venturia inaequalis (Cooke) G. Wint. is one of the major apple diseases worldwide. In 1994, the disease caused severe losses particularly in apple orchards of the Akkar mountainous areas of Lebanon, although more than 10 fungicide sprays were applied. A total of 230 isolates of V. inaequalis were collected from 23 orchards and single-spore colonies were prepared. The orchards were selected to represent the major apple-growing areas in Lebanon: Akkar in the north, Kfardibian in northeast Beirut, and Barouk in southeast Beirut. In vitro tests were conducted to evaluate the level of resistance to benzimidazoles and sterol biosynthesis inhibitors (SBI). All isolates tested except one were resistant to benomyl and thiophanate-methyl at 1 μg/ml. The majority of isolates were not inhibited at concentrations as high as 50 μg/ml in mycelial growth. Similarly, the majority of the isolates were not inhibited by benomyl at 1, 5, and 50 μg/ml in spore germination tests. Preliminary in vivo tests with benomyl concerning resistance to benzimidazoles correlated well with in vitro results. All the isolates were inhibited by fenari-mol at 0.25 μg/ml (1) indicating that all the isolates can be considered sensitive to this fungicide. However, the sensitivity levels varied among the various isolates with the ED50 for fenarimol ranging between 0.002 and 0.052 μg/ml. Two new SBIs, bromocunazol and fenbuconazol, not registered for use in Lebanon at the time this study was performed, were also tested. Their ED50 ranged from 0.0089 to 0.025 μg/ml for bromocunazol and from 0.008 to 0.039 μg/ml for fenbuconazol, both indicating a good level of in vitro activity. These results indicate that resistance to benzimidazol is widespread in Lebanon while resistance to SBIs has not yet been detected. Reference: (1) W. Köller et al. Plant Dis. 75:726, 1991.