bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of Crown Gall, Caused by Agrobacterium tumefaciens on Geraldton Wax (Chamelaucium uncinatum) in South Africa
Authors: Carstens E. , Dawood Z. , Mansvelt E. L. , Serfontein S. , Malan D. G. 
Published: May 2007

Geraldton wax (Chamelaucium uncinatum, family Myrtaceae) plants are grown as cutflowers for the export market in South Africa. In July 1998, gall-like structures were observed on collars and roots of Geraldton wax plants in commercial fields in Wellington. The galls were observed after plants exhibited poor growth. The galls varied in size and in texture from soft and spongy to hard. Secondary symptoms involved poor root development and browning of stem tissues near galls. Isolations from the galls yielded nearly pure cultures of a Gram negative, rod-shaped bacterium on Roy Sauer medium (2), typical of an Agrobacterium sp. Carbon source utilization testing with the Biolog GN Bacterial Identification System (version 3.50) confirmed the bacterium as a biovar of A. tumefaciens with a similarity of 0.88. Pathogenicity was confirmed by injecting 4- to 6-week old tomato and tobacco plants and 1-year-old Geraldton wax plants with approximately 5 μl of the bacterial suspension (108 CFU/ml) in sterile, distilled water. Inoculated plants were then transferred to a greenhouse at 25°C. Galls developed 1 month after inoculation. The bacterium was readily reisolated from the inoculated plants. A. tumefaciens is endemic to South Africa and has a very wide host range that includes several ornamentals (1). This is the first report of A. tumefaciens on Geraldton wax plants in South Africa. References: (1) J. F. Bradbury. 1986. Guide to Plant Pathogenic Bacteria. CAB Int., Slough, U.K. (2) N. W. Schaad. 1988. Laboratory Guide for Identification of Plant Pathogenic Bacteria. The American Phytopathological Society, St. Paul, MN.
First Report of East African Cassava Mosaic Begomovirus in Ghana
Authors: Offei S. K. , Owuna-Kwakye M. , Thottappilly G. 
Published: May 2007

Virus species causing cassava mosaic disease have been categorized into three classes based on their reaction with monoclonal antibodies (MAbs) and their distribution (2). These viruses have different, scarcely overlapping distribution: African cassava mosaic begomovirus (ACMV) occurs in Africa west of the Rift Valley and in South Africa; East African cassava mosaic (EACMV) occurs in Africa east of the Rift Valley and in Madagascar; and Indian cassava mosaic virus (ICMV) occurs in India and Sri Lanka (2). During 1998, surveys were conducted in farmers' fields in Ghana to assess the incidence and reaction of local cassava cultivars to cassava mosaic disease. Leaf samples from symptomatic plants were indexed by triple antibody sandwich-enzyme-linked immunosorbent assay with crude extracts and monoclonal antibodies obtained from the International Institute of Tropical Agriculture (IITA). Each sample was assayed with monoclonal antibody SCR 23, which detects ACMV and EACMV, SCR 33, which detects ACMV, and SCR 58, which detects ICMV. None of the samples reacted with SCR 58. Two of the samples collected from the western region of Ghana produced strong reactions with MAb SCR23 but did not react with ACMV-specific MAb SCR 33. This result was consistent in three separate experiments conducted on the samples, confirming that the virus was EACMV and not ACMV. The results extend the work by Ogbe et al. (1) and provide further evidence of the occurrence of EACMV in west Africa. References: (1) F. O. Ogbe et al. Plant Dis 83:398, 1999. (2) M. M. Swanson and B. D. Harrison. Trop. Sci. 34:15, 1994.
Rhizoctonia Species and Anastomosis Groups from Corn Kernels in Turkey
Authors: Demirci E. , Kordali S. 
Published: May 2007

In 1996, 165 samples of corn (Zea mays L.) kernels to be tested for seed-borne fungi were obtained from five provinces throughout the major corn-producing areas in the eastern Black Sea Region of Turkey: Artvin (41 samples), Rize (28 samples), Trabzon (32 samples), Giresun (30 samples), and Ordu (34 samples). A subsample of kernels (≈100 g each) from each sample was surface-disinfected in 3.5% NaOCl for 1 min. Kernels were washed in three changes of sterile water, and 100 kernels per subsample were placed in petri plates (5 kernels per plate) containing potato dextrose agar. After 5 to 7 days of incubation at 25°C in the dark, cultures were examined at 40× magnification for mycelia of Rhizoctonia spp. From 16,500 kernels examined, 40 isolates of Rhizoctonia spp. were recovered and characterized according to colony morphology and hyphal anastomosis using known tester isolates of Rhizoctonia spp. (1). Of these isolates, 10 were identified as R. solani, 18 as R. zeae, and 12 as binucleate Rhizoctonia sp. R. solani isolates were assigned to three anastomosis groups (AG): AG-4 (two isolates), AG-5 (two isolates), and AG-10 (six isolates). Binucleate Rhizoctonia sp. isolates were all assigned to AG-Ba. R. solani AG-4 and -5 and binucleate Rhizoctonia AG-Ba isolates were obtained from Artvin; R. solani AG-10 isolates were obtained from Ordu; and R. zeae isolates were obtained from Trabzon and Giresun. This is the first reported observation of Rhizoctonia spp. and anastomosis groups on corn kernels from Turkey. Reference: (1) B. Sneh et al. 1991. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN.
Identification of Rhizoctonia solani AG-UNK from Rice and Rice Fields in Texas as AG-11
Authors: Jones R. K. , Carling D. E. 
Published: May 2007

A survey of Texas rice fields in 1984 and 1985 yielded collections of Rhizoctonia solani AG-1 IA (causal agent of sheath blight of rice), R. oryzae (causal agent of sheath spot of rice), and a collection of eight multinucleate Rhizoctonia solani-like isolates that would interanastomose, but not anastomose, with tester isolates of AG-1 through AG-8 (representing those available at that time). In 1985, the isolates were characterized as R. solani AG-UNK (2). Isolates were recovered as atypical sclerotia from elutriated field soils in rice-soybean and rice-fallow rotations. Isolates also were recovered from late-season stem lesions nearly identical to those associated with sheath spot disease and from rice residues at locations throughout the upper Gulf Coast of Texas but at extremely low frequencies compared with recovery of R. solani AG-1 IA and R. oryzae. Teleomorphs of R. solani AG-UNK were observed during middle to late season on rice sheaths and matched descriptions of Thanatephorus cucumeris. Isolates were pathogenic on rice and soybean foliage in greenhouse trials but caused no significant yield losses when inoculated on adult rice plants (50 days after emergence) in field trials (2). Isolates exhibited mean hyphal diameters of 5.1 μm, averaged 8.3 nuclei per penultimate cell, grew 0.53 mm/h at 28°C on potato dextrose agar, and were negative in phenol tests (2). From samples maintained in storage during the past 15 years, the isolates have now been identified as AG-11 based on positive anastomosis with tester strains of AG-11 (1). This report records the occurrence of AG-11 in Texas, establishes the identity of the AG-UNK group, and expands the known geographic range of AG-11 in the United States. References: (1) D. E. Carling et al. Phytopathology 84:1387, 1994. (2) R. K. Jones and S. B. Belmar. Plant Dis. 73:1004, 1989.
First Report of Stachybotrys chartarum Causing Soybean Root Rot
Authors: Li S. , Hartman G. L. 
Published: May 2007

Stachybotrys chartarum (Ehrenb. ex Link) S.J. Hughes was isolated from surface-disinfested soybean (Glycine max (L.) Merr.) root lesions. The fungus was cultured on potato dextrose agar, and its morphology was examined by light and environmental scanning electron microscopy. Conidiophores were determinate, macronematous, solitary or in groups, and simple or irregularly branched. Phialides occurred in whorls and were obovate or ellipsoidal. Conidia were unicellular, round to ellipsoidal, 5 to 13 × 4 to 7 μm, initially hyaline, smooth-walled, and dark brown to black and rough-walled when mature. A pure culture obtained from infected soybean roots was used to test pathogenicity under greenhouse and growth-chamber conditions. S. chartarum was grown on sterilized sorghum grain for 2 weeks and placed in soil 2 to 3 cm below sown soybean seeds. Noninfested sorghum grain was used as a control. All soybean plants inoculated with S. chartarum had root lesions ranging from 7 to 25 mm 21 days after sowing, while control plants did not have any measurable root rot. The DNA sequence of the internal transcribed spacer (ITS) region was 100% identical to S. chartarum strain ATCC 9182 (1) but differed from all published sequences of other Stachybotrys and Memnoniella spp. in GenBank (1). Polymerase chain reaction with S. chartarum-specific primer StacR3 and IT51 (1) amplified a 198-bp DNA fragment from the total genomic DNA. The molecular evidence further supports the identification of S. chartarum isolated from soybean. This is the first report of S. chartarum causing soybean root rot. Reference: (1) R. A. Haugland and J. L. Heckman. Mol. Cell. Probes 12:387, 1998.
Fusarium oxysporum and F. sambucinum Associated with Root Rot of Amaranthus hybridus in South Africa
Authors: Chen W. , Swart W. J. 
Published: May 2007

Amaranthus hybridus has been identified as an important alternative vegetable crop with potential for increased commercial production in South Africa (1). In summer 1999, severe losses occurred in a large plot of 2-month-old A. hybridus plants on an experimental farm near Bloemfontein, South Africa. More than 90% of the plants were severely stunted, with chlorotic foliage that was wilted in most cases. Root rot was present in all symptomatic plants and was clearly visible as an amber to brown discoloration of tap and secondary roots; in severe cases, white mycelium was clearly visible on diseased root tissue. Isolations from symptomatic roots were made on potato dextrose agar (PDA) amended with streptomycin sulfate. Isolates (N = 121) were recovered from diseased roots (n = 89). The two most frequently isolated fungi were transferred to carnation leaf agar and identified as Fusarium oxysporum (n = 90, 74%) and F. sambucinum (n = 29, 24%). Pathogenicity tests with one isolate of each species were performed in the greenhouse on 1-month-old potted A. hybridus seedlings (10 plants per treatment). A single hyphal tip of each isolate was transferred to PDA and incubated at 25°C for 7 days in the dark. Five 4-mm-diameter mycelial plugs were taken and placed directly on the taproot of each plant, halfway along the length and ≈30 mm below the soil surface. Control plants were treated with uncolonized PDA plugs. Seedlings inoculated with either fungus exhibited wilting within 7 days; stunting, chlorosis (pale green to yellow), and root necrosis after 2 weeks; and mortality after 4 weeks. Inoculated plants were removed from pots after 3 weeks, roots were washed free of potting soil, and necrotic lesion length was measured. Necrosis and discoloration of root tissue were similar to those observed in field plants. The mean length of tissue necrosis induced by the fungi was 22.5 and 34.8 mm for F. oxysporum and F. sambucinum, respectively. F. sambucinum, thus, was more pathogenic than F. oxysporum despite being recovered significantly less often from field plants. Control plants inoculated with noninfested PDA plugs remained healthy. The presence of both pathogens was confirmed by reisolation from artificially inoculated taproots of all plants. No Fusarium spp. were recovered from the 10 control treatments. F. oxysporum has been reported on diseased red root pigweed (A. retroflexus) in the United States (2), but this is the first report of both F. oxysporum and F. sambucinum as causal agents of root rot in A. hybridus. These pathogens, therefore, must be considered a potential threat to commercial production of A. hybridus in South Africa and elsewhere. References: (1) W. J. Swart et al. S. Afr. J. Sci. 93:22, 1997. (2) R. M. Harveson and C. M. Rush. Plant Dis. 81:85, 1997.
Petal Blight of Sunflower Caused by Itersonilia perplexans
Authors: Seijo T. E. , McGovern R. J. , Marenco de Blandino A. 
Published: May 2007

In February 1999, a cut-flower grower from Florida reported post-harvest losses of approximately 25% in Helianthus annuus (sunflower) cvs. Sunrich Orange and Sunbright. Symptoms began as small, pinpoint brown lesions on the petals, which enlarged and coalesced, leading to necrosis of the entire blossom. Symptomatic petals were surface disinfested for 30 sec with 0.5% NaOCl and suspended over plates containing acidified 25% potato-dextrose agar. Petals adhered to lids of the petri dishes by the surface tension of the water on the petals. Itersonilia perplexans Derx was consistently isolated. Inoculation of sunflower with I. perplexans was achieved using three detached, mature blossoms of the cv. Sundance Kid with their pedicels placed in sterile water. Each blossom was inoculated with 3.5 ml of a spore suspension (1 × 105 spores/ml) applied as a spray. Three noninoculated control blossoms were sprayed with sterile, distilled water. Blossoms were incubated in a controlled environment chamber at near 100% RH, a constant temperature of 18°C, and a 12-h photoperiod. Three days following inoculation all of the inoculated blossoms were symptomatic, with necrosis ranging from 50 to 100% on individual petals. I. perplexans was recovered from all of the inoculated blossoms. Noninoculated controls remained symptomless, and I. perplexans was not recovered. I. perplexans has been reported to cause lesions on the cotyledons, first true leaves, and the hypocotyl region of sunflower seedlings in Canada and Uruguay (1,2). However, this is the first report of post-harvest petal blight in sunflower caused by I. perplexans and the first report in the United States of infection of sunflower by I. perplexans. References: (1) W. E. Sackston. Can. Phytopath. Soc. 1952:22, 1953. (2) W. E. Sackston. Phytopathology. 48:108, 1958.
Occurrence of Bacterial Brown Spot on Dry Beans in Zimbabwe
Authors: Fourie D. , Mukoko O. 
Published: May 2007

A previously unreported leaf spot disease was observed in dry bean variety trials in Harare, Zimbabwe, during March 2000. It was subsequently noticed on the cultivars Ex-Rico and C20 in commercial fields. The irregular, brown, necrotic lesions (0.5 to 5 mm in diameter) resembled typical symptoms of bacterial brown spot. A fluorescent bacterium was isolated from diseased leaf samples on King's B medium. LOPAT tests (2) classified the bacterium as a Group 1a fluorescent plant pathogenic pseudomonad. Agglutination with a specific antibody reagent, from the Adgen Express test kit, positively identified the bacterium as Pseudomonas syringae pv. syringae, the causal organism of bacterial brown spot. The pathogen was distinguished from P. syringae pv. phaseoli, the halo blight organism, by its ability to utilize mannitol, inositol, and sorbitol and its ability to grow on KBC medium (3). The utilization of sucrose as a sole carbon source distinguished the pathogen from P. viridiflava. Pathogenicity of isolates was verified by inoculating young attached pods of the cultivar Teebus, using the method of Cheng et al. (1). Control plants were inoculated with a sterile syringe needle dipped in sterile distilled water. Inoculated plants were maintained in a greenhouse at 28°C day/18°C night for 4 days before being evaluated for symptom development. P. syringae pv. syringae was consistently recovered from typical lesions that developed on inoculated pods. No symptoms developed on control pods. This is the first report of bacterial brown spot caused by P. syringae pv. syringae on dry beans in Zimbabwe. P. syringae pv. syringae was, however, isolated in South Africa from extracts of bean seed received from Zimbabwe in 1996, although it is uncertain whether the disease actually occurred in the field during that specific season. References: (1) G. Y. Cheng et al. Plant Dis. 73:419, 1989. (2) R. A. Lelliott et al. J. Appl. Bacteriol. 29:470, 1966. (3) S. K. Mohan and N. W. Schaad. Phytopathology 77:1390, 1987.
First Report of Leaf Blight and Stem Dieback of St. John's-Wort Caused by Diploceras hypericinum in Oregon
Authors: Putnam M. L. 
Published: May 2007

St. John's-wort, Hypericum perforatum L., was formerly considered a noxious weed in the Pacific Northwest and is now grown commercially for its medicinal properties. In May 1999, plants from a 5-ha field in Jefferson County, OR, were observed with yellowing leaves and stem dieback. Lower leaves showed marginal necrosis or circular, expanding, uniformly brown, unremarkable leaf lesions that appeared randomly over the lamina and consumed from a quarter to nearly the entire leaf area. Remaining leaf tissue was chlorotic, and affected leaves eventually abscised. Infection of the stems resulted in girdling lesions 0.5 to 1.0 cm in length that caused chlorosis, wilting, and eventual dieback of tissues distal to the lesion. Diploceras hypericinum (Cesati) Diedicke was sporulating on affected stems and leaves. The fungus was isolated from surface-disinfested tissue onto 1.5% water agar. A single-spore isolate was used to inoculate 10-month-old plants raised from seed in sand. Spores from 6-week-old cultures grown on 50% potato-dextrose agar were harvested, suspended in phosphate buffer with 0.2% gelatin (PBG), and sprayed onto three plants using a DeVilbiss atomizer. Inoculum concentration was 7 × 103 and 3 ml per plant were used (plants were 8 to 10 cm tall). Three control plants were sprayed with sterile PBG. Inoculated and control plants were separately bagged to retain moisture and maintained at 22 to 25°C. Four days later, inoculated plants exhibited leaf spots similar to those originally observed, followed by stem dieback. D. hypericinum was isolated from all inoculated plants but not from control plants. The known distribution of D. hypericinum is France, Germany, Portugal, Sweden, Greece, and Ontario, Canada (1,2). This is the first report of D. hypericinum causing leaf blight and stem dieback of St. John's-wort in the United States. References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN. (2) T. R. Nag Raj. 1993. Coelomycetous Anamorphs with Appendage-bearing Conidia. Mycologue Publications, Waterloo, Canada.
First Report of a Tospovirus on Sunflower (Helianthus annus L.) from India
Authors: Subbaiah K. Venkata , Sai Gopal D. V. R. , Krishna Reddy M. 
Published: May 2007

Virus-like symptoms were observed on sunflower in and around Tirupati during January 1998. Infected plants exhibited severe mosaic, systemic necrosis along the stem and floral heads, leaf distortion, and ringspots on leaves. The causal virus, mechanically transmissible from sunflower to sunflower cvs. Morden, MHSF8, MHSF18, KBHS1, and Cargil, developed symptoms like those in the original plant. The virus caused chlorotic and necrotic spots on Chenopodium amaranticolor, chlorotic and necrotic rings on cowpea cv. C-152, chlorotic spots on Datura metal and Petunia hybrida, chlorotic rings and systemic infection on Gomphrena globosa, tarlike symptoms on Catharanthus roseus, and local brown lesions on Cassia tora (1). Virus was isolated from infected sunflower leaves (2), and particles in negatively stained preparations were enveloped and 80 to 90 nm in diameter. Cytopathic effects included accumulation of virus particles in the endoplasmic reticulum, the formation of viroplasm, and aggregates consisting of nonenveloped viral nucleocapsids in the cytoplasm of ultrathin sections of infected sunflower leaves. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis of capsid protein resolved as a single band of 31 kD. The dsRNA isolated from infected sunflower leaves resolved as three bands of 9, 4.9, and 3 kb in 2% agarose gel electrophoresis. In enzyme-linked immunosorbent assay, the purified virus reacted with homologous and Peanut bud necrosis virus (PBNV-ICRISAT, India) antisera and not to polyclonal antibodies to Iris yellow spot virus (Netherlands), Tomato spotted wilt virus-T (Georgia), Impatiens necrotic spot virus, and several isolates of Cucumber mosaic virus (CMV-B, CMV-C, CMV-To). In western blotting analysis, the virus coat protein reacted with homologous and PBNV antisera corresponding to coat protein band of 31 kD. In reverse transcription polymerase chain reaction, the viral RNA was amplified by using primers derived from NP gene sequence of PBNV and Watermelon silver mottle virus (WSMV). Based on these properties, the virus causing sunflower mosaic followed by necrosis in India was identified as a tospovirus, which may be as a distinct isolate of sero group IV. References: (1) A. A. Brunt et al. Viruses of Plants Online. 1996. Australian National University, Canberra, 1996. (2) D. V. R. Reddy et al. Bud necrosis virus: A disease of peanut caused by Tomato spotted wilt virus. ICRISAT Inf. Bull. No. 31, 1991.
Dicentra, Epimedium, and Heuchera: New Perennial Ornamental Hosts of Tobacco rattle virus in the United States
Authors: Lockhart B. E. L. 
Published: May 2007

Yellow ringspotting and concentric line patterns in plants of Dicentra (bleeding heart), Epimedium (barrenwort), and Heuchera (coral bells) from commercial nurseries and home gardens in Minnesota, Michigan, and Massachusetts were associated with infection by Tobacco rattle virus (TRV), which was identified by particle morphology, enzyme-linked immunosorbent assay and immunosorbent electron microscopy. No other viruslike particles were observed by electron microscopy in partially purified preparations of TRV-infected leaf tissue, and TRV was not detected in asymptomatic plants. This is the first report of TRV occurrence in Dicentra in the United States and the first report of TRV occurrence in Epimedium and Heuchera. In previous reports (1,2) we have called attention to the increasing incidence of TRV in vegetatively propagated perennial ornamental plant species in the United States and to the potential for virus spread to crops such as potato, in which TRV has not been reported in the midwestern United States. It is possible that increased international trade in vegetatively propagated ornamental plants may be resulting in the introduction of TRV and other exotic viruses into the United States and elsewhere. It is also possible that the natural occurrence of TRV in North America may be actually more widespread than has been reported. References: (1) B. E. Lockhart et al. Plant Dis. 79:1249, 1995. (2) B. E. Lockhart and J. A. Westendorp. Plant Dis. 82:712, 1998.