bluuebunny/crossref_metadata_2025 huggingface dataset:
Occurrence of Anthracnose Caused by Colletotrichum malvarum on Althaea officinalis in Italy
Authors: Tosi L. , Buonaurio R. , Cappelli C.
Published: May 2007

The cultivation of medicinal plants is increasing in some areas of central Italy where the climate is suitable for organic farming and the production of high-quality plant products. During April and May 2003, plants of Althaea officinalis L. at the seedling stage (two-to-four true leaves) maintained in unheated greenhouses before their transplantation to open fields showed an unusual foliar disease. Necrotic leaf spots of variable shape and size were followed by a rapid wilting of leaves that frequently resulted in a blight of the young plants. Small leaf pieces showing symptoms were sampled, surface treated in 0.1% HgCl2 for 30 s, rinsed twice in sterile water, placed on potato dextrose agar (PDA) (pH 5.5) in petri dishes, and incubated for 7 days at 25 ± 2°C. Colletotrichum malvarum (Braun & Casp.) Southworth (1,2) was consistently recovered from affected tissues. The fungus produced dark colonies with whitish aerial mycelium and acervuli containing hyaline, cylindrical conidia (14 to 25 × 3 to 6 μm) on PDA. The pathogenicity of four fungal isolates was tested by inoculating two, true leaves of 10 plants (A. officinalis) with a conidial suspension (5 × 105 conidia ml-1) from a 10-day-old culture. Plants sprayed with water served as controls. All seedlings were placed in a greenhouse at 24± 2°C under natural light conditions and covered with plastic bags for the first 24 h. Each pathogenicity test was repeated one time. After 5 to 7 days, the inoculated seedlings showed small necrotic leaf spots identical to those observed under natural conditions. Affected leaf areas rapidly enlarged and within a few days, the young plants wilted. No symptoms appeared on the noninoculated controls. C. malvarum was consistently reisolated from the symptomatic test seedlings, whereas the fungus was never isolated from control plants. Standard seed health methods (agar plate and blotter) carried out on samples from the same seed lots used for the unheated greenhouse trials were negative for the presence of the pathogen. The occurrence of anthracnose may be attributed to windborne conidia of C. malvarum coming from infected wild malvaceae species and cultivated hosts grown in open fields in the neighborhood of seedling greenhouses. To our knowledge, this is the first report of C. malvarum on A. officinalis in Italy.

References: (1) W. Brandenburger. Page 386 in: Parasitische pilze an gefäbpflanzen in Europa. Fisher Verlag, Stuttgart, Germany, 1985. (2) B. C. Sutton. The genus Glomerella and its anamoroph Colletotrichum. Pages 1–26 in: Colletotrichum, Biology, Pathology and Control. J. A. Bailey and M. J. Jeger eds. CAB International, Wallingford, U.K., 1992.
First Report of Zucchini yellow mosaic virus in Bottlegourd (Lagenaria siceraria) in India
Authors: Verma Raj , Ahlawat Y. S. , Tomer S. P. S. , Prakash Satya , Pant R. P.
Published: May 2007

In December 2002, bottlegourd (Lagenaria siceraria L.) plants grown as a commercial crop in Pune, India (western Maharashtra) showed severe mosaic, interveinal chlorosis, and leaf deformation that resulted in fern-leaf appearance and severe fruit distortion in approximately 70% of the plants. Crude sap of collected samples was used to mechanically inoculate uninfected glasshouse-grown bottlegourd plants that reproduced symptoms observed in the field. Sap extracts from these glasshouse infected bottlegourd plants were used to mechanically inoculate selected indicator hosts. Chlorotic local lesions were produced on Chenopodium amaranticolor, and systemic symptoms were produced on Benincasa hispida, Citrullus lanatus, Cucumis sativus, Cucurbita moschata, C. pepo, Luffa cylindrical, and Trichosanthes anguina. The virus was specifically identified with serological testing using direct antigen coating enzyme-linked immunosorbent assay. The virus reacted strongly to Zucchini yellow mosaic virus (ZYMV) antiserum and did not react to Papaya ring spot virus-P (PRSV-P), Cucumber mosaic virus (CMV), and Watermelon mosaic virus (WMV) antisera. Electron microscopic examination of leaf-dip preparation from infected plants showed flexuous filamentous particles (720 to 760 nm long) that are typical of potyviruses. Natural infection of bottlegourd by ZYMV has been reported in the Hawaiian Islands (1). To our knowledge, this is the first report of this potentially destructive virus in bottlegourd in India.

Reference: (1) D. E. Ullman et al. Plant Dis. 75:367, 1991.
Variation in Responses of Sunflower Cultivars to the Parasitic Weed Broomrape
Authors: Eizenberg H. , Plakhine D. , Hershenhorn J. , Kleifeld Y. , Rubin B.
Published: May 2007

Development of four Orobanche species, O. cumana, O. aegyptiaca, O. ramosa, and O. cernua, was compared on resistant and susceptible sunflower cultivars. Sunflower plants were infected by O. cumana, O. aegyptiaca, and O. ramosa, but not by O. cernua, in field and greenhouse studies. However, cultivating the hosts and parasites in a polyethylene bag system allowed the observation that sunflower induced O. cernua seed germination. This difference demonstrates that O. cernua is unique from the other three species. O. cumana, O. aegyptiaca, and O. ramosa attached to and developed tubercles on the susceptible sunflower ‘Adi.’ On the resistant ‘Ambar’ sunflower, a greater percentage of tubercles were degenerated or dead than on the susceptible cultivar. Thus, resistance of Ambar appears to manifest during tubercle development. Seed production of Adi sunflower was greatly reduced with infection by O. cumana.
A Computer Program to Improve the Efficiency and Accuracy of Postulating Race-Specific Resistance Genes
Authors: Wamishe Yeshi A. , Thompson Kevin C. , Milus Eugene A.
Published: May 2007

Gene postulation has been the most widely used technique to determine the presence of particular rust resistance genes in lines of small grains. It applies the principles of gene-for-gene specificity to determine the most probable race-specific resistance genes present in host lines. As the numbers of lines, resistance genes, and races increase, postulation based on visual comparisons of infection types becomes more complex and laborious, and errors may occur. A computer program was developed to facilitate identification of race-specific leaf rust (Lr) genes in wheat (Triticum aestivum). Seedlings of 116 contemporary lines of soft red winter wheat and 24 Thatcher isolines (each Thatcher isoline with a single Lr gene) were inoculated with 22 races of Puccinia triticina. Infection types were recorded on the standard 0 to 4 scale where infection types 3 and 4 were considered high (line was susceptible; race was virulent) and others were low (line was resistant; race was avirulent). Based on the gene-for-gene concept, lines susceptible to a particular race cannot have an Lr gene for which the race is avirulent. For each line, step 1 of the program summarized results from races that were virulent on the line to definitively exclude Lr genes from the line, and this exclusion resulted in a relatively short list of Lr genes that could be present. Step 2 of the program utilized data from races that were avirulent on the line, and the output listed the low infection types produced on the line and the isolines with Lr genes that were not excluded in step 1. Of these Lr genes, a gene was considered present if the low infection type produced on the line by one or more races matched the low infection type on the corresponding isoline. Otherwise, the gene was considered possibly present. Epistatic effects of one or more Lr genes prevented definitive inclusion or exclusion of genes considered possibly present. If the low infection type produced on the line was lower than that on any of the isolines listed in step 2, then the line was considered to have an unidentified Lr gene; i.e., a gene that was not in the set of 24 isolines. This program facilitated the objective and accurate postulation of Lr genes and could be adapted to other host-pathogen systems.
Management of Potato Late Blight in the Peruvian Highlands: Evaluating the Benefits of Farmer Field Schools and Farmer Participatory Research
Authors: Ortiz O. , Garrett K. A. , Health J. J. , Orrego R. , Nelson R. J.
Published: May 2007

Farmer field school programs incorporating farmer participatory research (FPR-FFS) have the potential to provide important benefits to their participants and to other farmers who benefit from improved cultivars and management techniques. An FPR-FFS program in San Miguel, Cajamarca, Peru, has been in place since 1999 with an emphasis on management of potato late blight, caused by Phytophthora infestans, the most important problem facing Andean potato growers. Farmers' knowledge of late blight was surveyed to determine useful components for the FPR-FFS curriculum. The benefits to participants of FPR-FFS programs were evaluated first by measuring knowledge of late blight management of participants and nonparticipants. Studies of the Peruvian FPR-FFS program indicate that participants are more knowledgeable and that their expertise further increases after an additional year of participation. The benefits to participants can be evaluated more directly by comparing the productivity of participants' farms compared with nonparticipants' farms. For the Peruvian FPR-FFS program, participants had significantly higher average levels of productivity. The benefits of FPR-FFS programs for the development of better cultivars and management techniques can be evaluated indirectly in terms of improved estimates of performance. Estimates of the overall performance of a particular cultivar or technique become more precise as data from more sites are included in calculating the estimate. A more direct evaluation of benefits from FPR-FFS input may be based on the ability of farmers in FPR-FFS programs to eliminate undesirable genotypes and to recommend desirable genotypes based on criteria in addition to those used by breeders.
First Report of Clubroot of Eruca sativa Caused by Plasmodiophora brassicae in Brazil
Authors: Paz Lima M. L. , Café-Filho A. C. , Nogueira N. L. , Rossi M. L. , Schuta L. R.
Published: May 2007

Eruca sativa Mill. (family Brassicaceae), with its origin in western Asia, is a culinary and pharmacological species cultivated in Europe, Brazil, and other countries. In the United States, it is a minor crop known as arugula or roquette. Clubroot on E. sativa has not been reported in Brazil and has been reported once in the United States in 1914 (1,2,3). On several occasions since 2000, stunted and wilted plants (cv. Rúcula Cultivada) were collected from growers' fields and greenhouses that had been direct-seeded in Vargem Bonita, DF (two fields and one greenhouse) and Quatro Barras, PR (two fields). The infected arugula crops were found in areas where other plants from the genus Brassica were traditionally cultivated. Disease incidence in individual fields varied from 20 to 80%. Diseased plants were severely affected with hypertrophic, malformed roots, and root galls resembling Woronin's description (4). Plasmodia and resting spores in thin sections prepared from root galls were observed with compound and electron microscopes. Pathogenicity tests were conducted on arugula and Brassica pekinensis (Lour.) Rupr. (universal host) with inoculum from naturally infected arugula. The soil of potted test plants at the four-to-five-leaf stage was drenched with a suspension of resting spores. Symptoms identical to those observed on the original plants were produced on all inoculated plants 2 to 3 weeks after inoculation. Control plants remained symptomless. The pathogen was positively identified as Plasmodiophora brassicae Wor. with the combination of macroscopic and microscopic symptoms and signs of the disease and pathogen. P. brassicae was first reported in Brazil in 1965 in the state of São Paulo and in the 1980s in Distrito Federal on several members of the Brassicae. To our knowledge, this is the first report of P. brassicae infecting E. sativa in Brazil. Arugula is a susceptible host and should not be planted on P. brassicae-infested land.

References: (1) D. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN. 1989. (2) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory, On-line publication. ARS, USDA, 2003. (3) J. S. Karling. The Plasmodiophorales. Published by J. S. karling, NY. 1942. (4) M. S. Woronin. Plasmodiophora brassicae the Cause of Cabbage Hernia. Phytopathological Classics 4. The American Phytopathological Society, Ithaca, NY, 1934.
First Report of Laminated Root Rot on Sabina przewalskii Caused by Phellinus weirii sensu stricto in China
Authors: Dai Y. C.
Published: May 2007

Members of the Phellinus weirii complex cause laminated root rot of living conifers. The cedar type (P. weirii (Murrill) Gilb. sensu stricto) of the complex is usually found on species of the Cupressaceae family, especially Thuja plicata in western North America, and the Douglas-fir type (P. sulphurascens Pilát) is found on species of the Pinaceae family (1,2,3). Outside North America, P. weirii occurs on species of Juniperus in the Ural Mountains, and P. sulphurascens occurs on other conifers in eastern Asia, including China (1). During a field inventory of wood-decay fungi in western China in 2003, laminated root rot of Sabina przewalskii (synonym Juniperus przewalskii) was found in natural forests of the Qilian Mountains in Qinghai Province (37°36′N and 102°15′E). Trees were approximately 80 to 150 years old and occurred in pure stands. Distinct disease patches that were as much as one hectare consisted of dead-standing and symptomatic trees, suggesting that the fungus spread by root contact. Symptomatic trees showed slow growth, thin crowns, and chlorotic foliage. After cutting several of the symptomatic trees, cambial necrosis and wood decay were found, and the trees apparently died when the cambial necrosis girdled the base of the trees. The wood of infected trees was reddish brown at the early stages of decay and later had numerous small cavities and separated into sheets at the junction of annual rings. Perennial, poroid, resupinate, dark brown basidiocarps formed on the root surface of dead trees. The basidiocarps had a monomitic hyphal system, hyphae without clamp connections, trama tissue with hyphoid setae, and thin-walled, hyaline, smooth, ellipsoid basidiospores. The fungus was identified as P. weirii and distinguished from P. sulphurascens by its perennial basidiocarps, smaller pores (5 to 8 versus 4 to 5 per mm), and narrower hyphoid setae (4 to 6 versus 5 to 10 μm in diameter). P. weirii also resembles P. ferrugineofuscus (P. Karst.) Bourdot in macro-morphology, but the latter species is a saprophyte and has allantoid to almost lunate basidiospores. The studied specimens of P. weirii and P. sulphurascens are preserved at the herbaria of the Botanical Museum of the University of Helsinki, the Institute of Applied Ecology, and the Chinese Academy of Sciences as DAOM 8734, Lowe 6960, TAA 52744, 55644, and 103812, and Dai 988, 2053, 2061, 2527, and 5067. To my knowledge, this is the first report of P. weirii sensu stricto from China and the first report of laminated root rot on S. przewalskii.

References: (1) Y. C. Dai and G. F. Qin. Fungal Sci. 13:101, 1998. (2) E. M. Hansen et al. Species limits for Phellinus weirii. Pages 119–127 in: Root and butt rots of forest tress. Int. Conf. Root and Butt Rots, INRA, France, 1998. (3) M. J. Larsen et al. Mycologia 86:121, 1994.
Field Evaluation of Transgenic Papaya Lines Carrying the Coat Protein Gene of Papaya ringspot virus in Taiwan
Authors: Bau Huey-Jiunn , Cheng Ying-Huey , Yu Tsong-Ann , Yang Jiu-Sherng , Liou Pan-Chi , Hsiao Chi-Hsiung , Lin Chien-Yih , Yeh Shyi-Dong
Published: May 2007

Four transgenic papaya lines expressing the coat protein (CP) gene of Papaya ringspot virus (PRSV) were evaluated under field conditions for their reaction to PRSV infection and fruit production in 1996 to 1999. Plants were exposed to natural virus inoculation by aphids in two adjacent fields in four different plantings at the same sites. None of the transgenic lines showed severe symptoms of PRSV whereas control nontransgenic plants were 100% severely infected 3 to 5 months after planting. In the first and second trials, 20 to 30% of the transgenic plants showed mild symptoms consisting of confined mottling or chlorotic spots on leaves. The number of transgenic plants with mild symptoms fluctuated according to the season and weather conditions, with a tendency to increase in the winter or rainy season and decrease in the summer. Also, the incidence of the mild symptoms in the third trial increased significantly due to infection by root rot fungi during the rainy season. Interestingly, there was no apparent adverse effect on fruit yield and quality in transgenic plants with mild symptoms. In the first and second experiments, transgenic lines yielded 10.8 to 11.6 and 54.3 to 56.7 times more marketable fruit, respectively, than controls. All transgenic plants produced fruit of marketable quality with no ringspots or distortion.
Natural Infection of Canavalia ensiformis with Tobacco mosaic virus in Venezuela
Authors: Marys E. , Ortega E. , Carballo O. , Ramis C.
Published: May 2007

Jack bean (Canavalia ensiformis) is a valuable green manure and cover-crop species. In late summer of 2002, jack bean plants showing severe stunting, leaf mosaic, mottling, distortion, and general yellowing were observed in fields located in Maracay, Aragua State, Venezuela. Sap from symptomatic leaves was used to mechanically inoculate healthy jack bean, and field symptoms were successfully reproduced. Similar inoculations on Nicotiana tabacum var. Sansum resulted in mosaic symptoms and leaf distortion. Electron microscopic examination of leafdip preparations showed filamentous rods resembling those of a tobamovirus. Tobacco mosaic virus (TMV) was specifically identified with TMV-specific polyclonal antibody (PVAS-958, ATTC) in enzyme-linked immunosorbent assay. Sequence analysis of a coat protein gene (CP) fragment amplified using reverse transcription-polymerase chain reaction (RT-PCR) with primers TMV-CP-F and TMV-CP-R (1) from total RNA confirmed the diagnosis. Nucleotide and deduced amino acid sequences of a 450-bp region of the RT-PCR product were 96 to 99% and 98 to 100% identical, respectively, to the TMV CP gene in GenBank Accession Nos. J02415 and X68110. On the basis of foliar symptoms, incidence of TMV in jack bean was more than 50% in this experimental field. The source of infection is not known. Because TMV is reported to be seedborne in many other plant species, testing jack bean seed stocks for TMV infection could have important implications on the future control of the virus. To our knowledge, this is the first report of natural infection of jack bean by a tobamovirus.

Reference: (1) N. J. Spence et al. Eur. J. Plant Pathol. 107:633, 2001.
First Report of Powdery Mildew (Oidium sp.) on Akebia quinata in Italy
Authors: Garibaldi A. , Bertetti D. , Gullino M. L.
Published: May 2007

Akebia quinata Decne., an ornamental species belonging to the family Lardizabalaceae, is used as a climbing species in gardens to cover walls as well as supports and is very much appreciated because of its dark red flowers. During the summer of 2003, severe outbreaks of a previously unknown powdery mildew were observed on established plantings in several gardens near Biella (northern Italy). The upper surfaces of leaves were covered with white mycelium, and the corresponding abaxial surface of infected leaves were chlorotic. Young, green stems also affected showed extended chlorosis. As the disease progressed, infected leaves turned yellow and died. Foot cell was cylindric and appressorium lobed. Conidia formed singly were hyaline, ellipsoid, and measured 26.4 to 45.6 × 10.6 to 15.6 μm (average 35.1 × 12.7 μm). Fibrosin bodies were not present. The pathogen was identified as Oidium sp. subgenus Pseudoidium (1) partially because cleistothecia were not observed. Conidial measurements are close to those reported for Microsphaera akebiae Sawada. Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of healthy A. quinata plants. Three plants of A. quinata were used as replicates. Noninoculated plants served as controls. Plants were maintained between 20 and 30°C in a garden located 5 km from where the disease was originally found. After 10 days, typical symptoms of powdery mildew developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of the presence of powdery mildew on A. quinata in Italy. The disease is currently restricted to the area of Biella. The presence of M. akebiae was recently reported in the Netherlands (2). Specimens of this disease are available at the DIVAPRA Collection at the University of Torino.

References: (1) U. Braun and S. Takamatsu. Schlechtendalia, 4:1, 2000. (2) M. Scholler and W. Gams. Nova Hedwigia, 67:101, 1998.
Resistance of Eight Different Clones of the Grape Cultivar Albariño to Plasmopara viticola
Authors: Boso S. , Santiago J. L. , Martínez M. C.
Published: May 2007

Resistance to downy mildew (Plasmopara viticola) was studied in eight clones of the grape (Vitis vinifera) cultivar Albariño (confirmed as such by DNA and ampelographic analysis) growing at the Misión Biológica de Galicia, Spain. Resistance to downy mildew was quantified using an image processor. Some clones (CSIC-10 and CSIC-11) were more resistant than others to leaf infection by P. viticola. However, the susceptibility of grape clusters did not differ significantly among the clones.
First Report of Shining Willow as a Host Plant for Septoria musiva
Authors: Feau N. , Bernier L.
Published: May 2007

During the summer of 2001, leaf spots resembling those caused by Septoria musiva Peck. were observed on shining willow (Salix lucida Mühl. subsp. lucida) at Leclerville, Québec, Canada (46°34′19″N,71°59′35″W). Affected leaves had brown, necrotic leaf spots (>5mm in diameter) surrounded by a darker brown halo. Conidia were cylindrical, straight to curved with 1 to 4 septa, 28 to 54 × 3.5 to 4 μm, and were produced in pycnidia located on the abaxial surface in the center of the leaf spots. The causal agent of this disease was successfully isolated by germinating the conidia on corn meal agar that was supplemented with streptomycin (50mg/ml) and chloramphenicol (300mg/ml) and followed with the transfer of the germinated conidia to potato dextrose agar. Leaf symptoms and morphology matched those of S. musiva, the cause of leaf spot and stem canker of hybrid poplars in North America (2,4). The internal transcribed spacers and the 5.8S portion of the rDNA were amplified using PCR with the ITS1 (5′-TCC GTA GGT GAA CCT GCG G-3′) and ITS2 (5′-GCT GCG TTC TTC ATC GAT GC-3′) primer pair on total genomic DNA extracted from a pure culture of the pathogen. The rDNA sequence obtained (GenBank Accession No. AY555277) had 100% identity at 506 base positions with the ITS1, 5.8S, and ITS2 of three S. musiva isolates from Québec and one from Wisconsin (GenBank Accession Nos. AY549464 to AY549467). To test for pathogenicity, excised leaf disks from plants propagated by softwood cuttings of the source plant and from one hybrid poplar clone (Populus maximowiczii × P. xjackii) were inoculated with 3 μl of a suspension of ground mycelium or sterile water (control). Disks were placed in a 24-well tissue culture plate with 1 ml of distilled water per well and incubated in a growth room maintained at 22°C with a 16-h photoperiod. After 1 month, symptoms were similar to those previously observed. Isolates collected from shining willow or hybrid poplar were able to induce S. musiva leaf spot symptoms on leaf disks excised from shining willow or the hybrid poplar clone. From symptomatic leaf disks, S. musiva was consistently reisolated. To our knowledge, this is the first report of S. musiva on a member of the genus Salix. S. didyma, S. salicicola, and S. salicina have been reported from leaves of species of Salix (1,3). Only a vague morphological description of S. didyma was found (3). Moreover, conidia of S. salicicola (20 to 50 × 2.5 to 3.5 μm) and S. salicina (40 to 60 μm long, unspecified width) overlap dimensions of S. musiva conidia (1). There is a need to reexamine the relationships between these species of Septoria. Evidently, the complete host range of S. musiva is not yet known.

References: (1) L. Lanier et al. Mycologie et Pathologie Forestières. Masson. Paris, 1978. (2) M. E. Ostry. Eur. J. For. Pathol. 17:158, 1987. (3) P. A. Saccardo. Sylloge fungurum omnium hucusque cognitorum. Patavii: Sumptibus Auctoris, 1882. (4) L. J. Spielman et al. Plant Dis. 70:968, 1986.
First Report of Black Sigatoka of Banana Caused by Mycosphaerella fijiensis on Grand Bahama Island
Authors: Ploetz R. C.
Published: May 2007

Black Sigatoka, which is also known as black leaf streak, is caused by Mycosphaerella fijiensis (anamorph Pseudocercospora [formerly Paracercospora) fijiensis]). It is the most important disease of commercially produced banana (Musa spp.) and also has a major impact on production for local consumption. Although the disease occurs throughout the humid tropics, it has been reported in the Caribbean from only Cuba, Hispaniola, and Jamaica (1). In February 2004, black Sigatoka was observed at two isolated and widely separated sites on Grand Bahama island (26.7°N, 78.5°W and 26.7°N, 78°W) on cvs. Silk AAB and Williams AAA, and a French Horn AAB plantain. Symptoms included wet, dark brown streaks on the adaxial leaf surface, 1 to 2 × 10 mm, with chlorotic haloes. Lesions enlarged to 5 × 20 mm and developed tan, necrotic centers; large, blackened, water-soaked areas that resulted from the coalescence of streaks were rare. The disease was confirmed by observing the following characteristics of P. fijiensis in necrotic lesions on preserved leaf specimens: simple conidiophores with a broadened base and one to several septa, straight to variously bent cercosporoid conidia as much as 100 μm long with two to several septa, and a conspicuously thickened scar at the base. Both plantings were several years old and new planting material that could have been infested with the pathogen had not been introduced since their establishment. Symptoms were not severe and were distributed sporadically in both locations. The disease was not observed at the only other large planting of banana on the island (26.6°N, 78.6°W). The sporadic and apparently new infestations of two of three banana plantings on the island suggest that the pathogen may have arrived recently via natural means, possibly from neighboring Florida (2). In contrast, black Sigatoka appears to have spread to other islands in the Caribbean via infested propagation materials (1). To my knowledge, this is the first report of black Sigatoka in the Bahamas, and with a previous report from Bhutan (1), represents the northernmost spread of this important disease.

References: (1) J. Carlier et al. Pages 37–79 in: Diseases of Banana, Abacá and Enset. D. R. Jones, ed. CABI Publishing. Wallingford, UK, 2000. (2) R. C. Ploetz and X. Mourichon. Plant Dis. 83:300, 1999.
Survival of Teliospores ofTilletia indicain Arizona Field Soils
Authors: Bonde M. R. , Nester S. E. , Olsen M. W. , Berner D. K.
Published: May 2007

The survival of teliospores of the Karnal bunt of wheat pathogen, Tilletia indica, was determined in field plots in Tucson, AZ. Two methods were used to test viability during a 48-month period in which 21-μm-pore-size polyester mesh bags of teliospore-infested soil were buried in irrigated and nonirrigated field plots at two sites. One method determined the total number of viable teliospores in a soil sample, regardless of whether or not they could be extracted from the soil using a sucrose centrifugation technique. The total number of viable teliospores declined over time in both irrigated and nonirrigated field plots and in the same soils in the laboratory. Based on nonlinear regressions, total number of viable teliospores decreased from 55.7% at time zero to 9.7 and 6.7% for nonirrigated and irrigated field soils, respectively, in 48 months. Total number of viable teliospores in soil in the laboratory decreased from 55.7 to 34.0% after 48 months. The second method determined germination percentages of teliospores extracted from the soil samples by means of a sucrose centrifugation technique. Based on linear regressions of transformed data, germination of teliospores extracted from irrigated and nonirrigated field soils, and control (laboratory) soil, significantly decreased over time. The rate of decrease in germination was significantly greater for teliospores from irrigated field plots than from nonirrigated plots and the laboratory soil. At time zero, 55.7% of teliospores germinated, and by 48 months, average germination of teliospores extracted from soil in nonirrigated plots had decreased to 13.6% compared with 4.4% in irrigated plots and 36.8% for teliospores in the laboratory control. Regression over time of total number of viable teliospores accounted for more of the overall variability than did regression over time of germination percentages of extracted teliospores. Neither field site nor soil depth had any effect on total number of viable teliospores or on teliospore germination percentages.
Recovery of Anastomosis Groups of Rhizoctonia solani from Different Latitudinal Positions and Influence of Temperatures on Their Growth and Survival
Authors: Harikrishnan R. , Yang X. B.
Published: May 2007

Multinucleate Rhizoctonia solani isolates were recovered from soybean fields from five locations at a range of latitudes from 33 to 46°N. Out of 143 multinucleate isolates recovered, 51 isolates were anastomosis group (AG)-1 (35.6%), 9 were AG-2-2 (6.2%), 40 were AG-4 (28%), and 15 were AG-5 (10.6%). The remaining 28 isolates (19.6%) failed to anastomose with any of the testers (AG-1, 2-2, 4, or 5). Among the four AGs, AG-1 was found mainly in the more southern latitudes in contrast to AG-2-2, which was found mostly in the more northern latitudes. AG-4 and AG-5 were distributed across all latitudes. Effects of temperature on growth, sclerotia production (range from 5 to 30°C with 5° increments), and saprophytic survival using infested straw (range from -10 to 30°C with 10° increments) were studied with representative isolates from AG-1, AG-2-2, AG-4, and AG-5 isolated from different locations. Results indicate differential effects of temperature on growth rate and sclerotia production among the isolates within each AG. Optimum temperature for growth rate of all isolates tested from the different AGs was between 25 and 30°C; whereas, for sclerotia production, it was 25°C. Isolates from AG-1 had the highest mean sclerotia production. Saprophytic survival of isolates from all AGs tested declined linearly over time and with decrease in temperature in the survival study. Saprophytic survival of all isolates irrespective of AG collected from the southernmost location was lower at low temperatures than that of isolates collected from higher latitudes. Our results suggest temperature dependent response among isolates within different AGs of R. solani.
Phenotypic and Genotypic Characterization of Uromyces appendiculatus from Phaseolus vulgaris in the Americas
Authors: Araya C. M. , Alleyne A. T. , Steadman J. R. , Eskridge K. M. , Coyne D. P.
Published: May 2007

Populations of 90 Uromyces appendiculatus isolates were collected from throughout the Americas and evaluated for virulence on 19 standard bean rust differentials, and also on 12 landraces of Phaseolus vulgaris from South and Central America. The landrace differentials represented geographical centers of bean domestication. Three groups were observed. Two groups were isolates from centers of bean domestication and a third heterogeneous group comprised isolates from countries in South and Central America. Molecular analysis using random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was also conducted on these isolates. Cluster analysis of the molecular profiles showed three groups that corresponded to those obtained by virulence tests. These results show a clear differentiation of the pathogen population along similar lines as its host and suggest parallel evolution in the bean rust pathosystem.
Fusarium Head Blight and Deoxynivalenol Accumulation of Barley in Eastern Canada: Cultivar Response and Correlation Analysis
Authors: Choo T. M. , Martin R. A. , Ho K. M. , Shen Q. , Fedak G. , Savard M. , Voldeng H. , Falk D. E. , Etienne M. , Sparry E.
Published: May 2007

Fusarium head blight of barley (Hordeum vulgare) is a devastating disease in many countries. We undertook a study to identify barley cultivars, if any, that are resistant to Fusarium head blight and deoxynivalenol (DON) accumulation and to determine if DON concentration is correlated with other plant traits in Eastern Canada and China. Barley cultivars were grown in the field under artificial inoculation conditions at two locations (Charlottetown and Ottawa) in Canada during two summers and at Hangzhou in China during two winters. Seed samples were collected for DON analysis from the barley performance trial at five locations in Ontario. None of the 64 barley cultivars were immune to Fusarium head blight infection. Two-row cultivars, however, were significantly more resistant to Fusarium head blight infection and DON accumulation than six-row cultivars. Three cultivars (Island, AC Alberte, and Chevron) were found to be most resistant, as they were consistently low in Fusarium head blight incidence and DON concentration in both Eastern Canada and China. In six-row barley, DON concentration was correlated positively with Fusarium head blight incidence at both Charlottetown and Ottawa, and it was negatively correlated with plant height at Ottawa. DON concentration and heading date were not consistently correlated. Barley yellow dwarf and powdery mildew appeared to have very little effect on Fusarium head blight infection. Susceptibility to DON accumulation did not result in low yield under natural infection conditions in Ontario. Cultivar × location interactions for DON concentration, Fusarium head blight incidence, and heading date were significant.
Effects of Reduced Tillage, Resistant Cultivars, and Reduced Fungicide Inputs on Progress of Early Leaf Spot of Peanut (Arachis hypogaea)
Authors: Monfort W. S. , Culbreath A. K. , Stevenson K. L. , Brenneman T. B. , Gorbet D. W. , Phatak S. C.
Published: May 2007

Field experiments were conducted in 2000 and 2001 on Georgia Green, Florida MDR-98, and C-99R peanut (Arachis hypogaea) cultivars in Tifton, GA, to determine the effects of tillage practices on early leaf spot (Cercospora arachidicola) epidemics under standard fungicide regimes and fungicide regimes with fewer applications. Leaf spot epidemics were suppressed in reduced tillage (strip-till) plots compared with conventional tillage plots and were suppressed in MDR-98 and C-99R cultivars compared with the standard runner-type cultivar, Georgia Green. Within tillage and cultivar combinations, leaf spot intensity typically was lower in plots treated with fungicides at standard intervals (seven total applications) than in those treated at extended intervals (four total applications). However, in most cases, leaf spot control in extended interval treatments in the strip-till system was comparable to that in the standard interval treatments in conventional tillage. Based on these results, the number of fungicide applications could be reduced without compromising control of leaf spot when reduced tillage is used, especially if combined with moderately resistant cultivars. Suppression of leaf spot epidemics in the strip-till plots did not coincide with higher yields in either year. In 2001, yields were lower in strip-till plots than in conventional tillage plots. Yields were typically higher in the cultivar C-99R than in Georgia Green, regardless of the tillage treatment.
Seed Transmission of Citrus leaf botch virus: Implications in Quarantine and Certification Programs
Authors: Guerri J. , Pina J. A. , Vives M. C. , Navarro L. , Moreno P.
Published: May 2007

Citrus leaf blotch virus (CLBV) was purified and characterized from a Nagami kumquat (Fortunella margarita (Lour.) Swingle), showing bud union crease when propagated on Troyer citrange (Citrus sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.) (2). The complete nucleotide sequence of its genomic RNA was determined (4), and biological and molecular diagnosis methods were developed (1,3). CLBV, detected in several citrus cultivars from Australia, the United States (Florida and California), Japan, and Spain is usually associated with bud union crease on citrange or citumelo (C. paradisi (Macfad.) × P. trifoliata). The economic importance of CLBV for the citrus industry is presently unknown since its incidence in different citrus areas has not been evaluated, and its actual involvement in causing bud union crease on trifoliate rootstocks has not yet been proved. To assess seed transmissibility of this virus, 120 to 210 seeds from CLBV-infected Troyer citrange, Nagami kumquat, or sour orange (Citrus aurantium L.) plants were grown in a greenhouse. Individual 4-month-old seedlings were analyzed for CLBV by reverse transcriptase polymerase chain reaction, and infection was confirmed by biological indexing on Dweet tangor (C. tangerina Hort. ex Tanaka × C. sinensis (L.) Osbeck) when seedlings were approximately 18 months old. Seed transmission was found in 2.50, 2.52, and 2.46% of the citrange, kumquat, and sour orange seedlings, respectively. This finding indicates that control of CLBV spread during citrus propagation will require, not only virus-free buds, but also rootstock seedlings that originate from CLBV-free seed source trees. Because CLBV is seed transmissible, regulations of citrus certification programs may need to be changed to include increased control of seed source trees. Also, international regulations for citrus seed movement likely will have to be augmented to include a phytosanitary certification indicating that seeds have been collected from CLBV-free trees.

References: (1) L. Galipienso et al. Plant Pathol. 49:308, 2000. (2) L. Galipienso et al. Arch. Virol. 146:357, 2001. (3) L. Galipienso et al. Eur. J. Plant Pathol. 110:175,2004. (4) M. C. Vives et al. Virology 287:225, 2001.
New Natural Hosts of Pepino mosaic virus in Spain
Authors: Córdoba M. C. , Martínez-Priego Ll. , Jordá C.
Published: May 2007

Pepino mosaic virus (PepMV) was first detected in Spain in 2000 (1). The virus infects tomato (Lycopersicon esculentum Mill.) crops and causes a variety of symptoms including leaf distortion, chlorosis, mosaic, blistering of the leaf surface, green striations on the stem and sepals, and fruit discoloration. PepMV is present along the southern and eastern regions of Spain (provinces of Granada, Almeria, Murcia, Alicante, Valencia, and Barcelona), Balearic, and the Canary Islands. In the summer and autumn of 2001 and 2002, virus-like symptoms were observed in native plants growing in or around tomato fields in Murcia and Almeria provinces. To study the alternate hosts that may serve as virus reservoirs, 62 samples of 42 common weed species, including asymptomatic plants, were collected and analyzed for PepMV using double-antibody sandwich enzyme-linked immunosorbent assay with a commercial antiserum (DSMZ As-0554; Biologische Bundesantstal, Braunschweig, Germany). The following weed hosts tested positive for PepMV: Bassia scoparia (L.) Voss., Calystegia sepium (L.) R.Br., Chenopodium murale L., Convolvulus althaeoides L., Convolvulus arvensis L., Conyza albida Willd. ex Spreng., Coronopus sp., Diplotaxis erucoides (L.) DC, Echium creticum L., E. humile Desf., Heliotropium europaeum L., Moricandia arvensis (L.) DC., Onopordum sp., Piptatherum multiflorum (Cav.) Beauv., Plantago afra L., Rumex sp., Sisymbrium irio L., Sonchus tenerrimus L., and Taraxacum vulgare (Lam.) Schrank. The presence of PepMV in these weed species was confirmed using reverse transcription-polymerase chain reaction with primers specific for PepMV (2). Although the number of samples examined may be insufficient to assess precisely the role of weed reservoirs in outbreaks of PepMV, these findings reveal potential virus sources and contribute to further understanding of PepMV epidemiology in Spain.

References: (1) C. Jordá et al. Plant Dis. 85:1292, 2001. (2) P. Martínez-Culebras et al. Eur. J. Plant Pathol. 108:887, 2002.
First Report of Cucurbit aphid-borne yellows virus in Spain
Authors: Juarez M. , Truniger V. , Aranda M. A.
Published: May 2007

In late spring 2003, field-grown melon plants (Cucumis melo L.) showing bright yellowing of older leaves were observed near Valladolises in Campo de Cartagena, Murcia, Spain. Symptoms resembled those caused by viruses of the genus Crinivirus (family Closteroviridae), but absence or very low populations of whiteflies were observed. However, diseased foci showed clear indications of heavy aphid infestations. Later, during the fall of 2003, squash plants (Cucurbita pepo L.) grown in open fields in the same area showed similar symptoms. Tissue print hybridizations to detect Cucurbit yellow stunting disorder virus (CYSDV) and Beet pseudo yellows virus (BPYV) in symptomatic samples were negative. CYSDV and BPYV are two yellowing-inducing criniviruses previously described in Spain. In contrast, standard double-antibody sandwich enzyme-linked immunosorbent assays (DAS-ELISA) with antiserum against Cucurbit aphid-borne yellows virus (CABYV; genus Polerovirus, family Luteoviridae) that was kindly provided by H. Lecoq (INRA-Montfavet Cedex, France) were consistently positive. Definitive confirmation of CABYV associated with symptomatic samples was obtained by performing reverse-transcription polymerase chain reaction (RT-PCR) analyses for the CABYV coat protein gene. Total RNA extracts (TRI reagent; Sigma Chemical, St. Louis, MO) were obtained from symptomatic and asymptomatic leaf samples and RT-PCR reactions were carried out using the primers 5′-GAATACGGTCGCGGCTAGAAATC-3′ (CE9) and 5′-CTATTTCGGGTTCTGGACCTGGC-3′ (CE10) based on the CABYV sequence published by Guilley et al. (2). A single DNA product of approximately 600 bp was obtained only from symptomatic samples. Amplified DNA fragments from two independent samples (samples 36-2 and 37-5) were cloned in E. coli and sequenced (GenBank Accession Nos. AY529653 and AY529654). Sequence comparisons showed a 95% nucleotide sequence identity between the two sequences. A 97% and 94% nucleotide sequence identity was found among 36-2 and 37-5, respectively and the CABYV sequence published by Guilley et al. (2). CABYV seems to be widespread throughout the Mediterranean Basin (1,3) but to our knowledge, it has not previously been described in Spain. Additionally, our data suggest that significant genetic variability might be present in the Spanish CABYV populations.

References: (1) Y. Abou-Jawdah et al. Crop Prot. 19:217, 2000. (2) H. Guilley et al. Virology 202:1012, 1994. (3) H. Lecoq et al. Plant Pathol. 41:749, 1992.
First Report of Downy Mildew Caused by Plasmopara obducens on Impatiens in California
Authors: Wegulo S. N. , Koike S. T. , Vilchez M. , Santos P.
Published: May 2007

During February 2004, diseased double impatiens (Impatiens walleriana) plants were received from a commercial grower in southern California. The upper surfaces of symptomatic leaves were pale yellow with no distinct lesions. Diseased leaves later wilted, and severely affected leaves abscised from the stem. At the nursery, only double impatiens plants in the Fiesta series were infected, and some cultivars were more heavily infected than others. Disease incidence in cv. Sparkler Hot pink was nearly 100%. The interior of infected leaves was colonized by coenocytic mycelium. A conspicuous white growth was observed only on the underside of leaves. Sporangiophores were hyaline, thin walled, emergent from stomata, and had slightly swollen bases. Sporangiophore branching was distinctly monopodial. Smaller sporangiophore branches were arranged at right angles to the supporting branches, and tips of branches measured 8 to 14 μm long. Sporangia were ovoid and hyaline with a single pore on the distal ends. Distal ends of sporangia were predominantly flat but occasionally had a slight papilla. Short pedicels were present on the attached ends. Sporangia measured 19.4 to 22.2 (-25.0) μm × 13.9 to 16.7 (-19.4) μm. Oospores were not observed in leaf tissue. On the basis of symptoms and morphology of the organism, the pathogen was identified as Plasmopara obducens J. Schröt. Pathogenicity tests were done on double type cvs. Fiesta, Tioga Red, and Tioga Cherry Red and on single type cvs. Cajun Watermelon and Accent Lilac. Plants were spray inoculated with sporangiospore suspensions (1 × 104 sporangiospores per milliliter), incubated for 24 h in a dew chamber (18 to 20°C), and then maintained in a greenhouse (22 to 24°C). Symptoms and signs of downy mildew developed after 12 days only on inoculated cv. Fiesta plants, and the pathogen morphology matched that of the originally observed pathogen. Nontreated control plants did not develop downy mildew. To our knowledge, this is the first report of downy mildew on impatiens in California. P. obducens is one of two causal agents of downy mildew of impatiens (2,4). The other pathogen, Bremiella sphaerosperma, has dichotomous sporangiophore branching and causes lesions with well-defined margins (2,4). In the United States, the disease has been recorded in the eastern and northeastern states and in Indiana, Minnesota, Mississippi, Montana, and Wisconsin (3). In Canada, the disease has been recorded in Manitoba and Quebec (1).

References: (1) I. L. Conners. An Annotated Index of Plant Diseases in Canada and Fungi Recorded on Plants in Alaska, Canada, and Greenland. Research Branch, Canada Department of Agriculture, Publication 1251, 1967. (2) O. Constantinescu. Mycologia 83:473, 1991. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, 1989. (4) G. W. Wilson. Bull. Torrey Bot. Club 34:387, 1907.