bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of Small Grains Genotypes Resistant to Wheat spindle streak mosaic virus
Authors: Cadle-Davidson L. , Sorrells M. E. , Gray S. M. , Bergstrom G. C.
Published: May 2007

Once Wheat spindle streak mosaic virus (WSSMV) becomes established in a field, the only available control strategy is the planting of resistant genotypes. In this study, we assessed 112 genotypes of winter wheat, rye, triticale, and barley for resistance to WSSMV in a 3-year trial in a field that had been used continuously for WSSMV evaluation for over 20 years. Because resistance to WSSMV reduces the percentage of plants that develop detectable virus titer and symptoms, we collected and analyzed disease incidence data. None of the genotypes was immune to infection. Sixty-two of the regionally adapted genotypes repeatedly expressed resistance to WSSMV, thus providing growers with a choice of cultivars resistant to WSSMV. Because of a significant interaction between genotypes and environment (year), genotypes should be assessed for incidence of symptomatic plants in multiple years, particularly when differentiating intermediate responses from highly susceptible and highly resistant responses.
Induced Resistance to Blackleg (Leptosphaeria maculans) Disease of Canola (Brassica napus) Caused by a Weakly Virulent Isolate of Leptosphaeria biglobosa
Authors: Chen Y. , Fernando W. G. D.
Published: May 2007

Blackleg of canola is a disease complex of at least two fungal species: Leptosphaeria maculans and L. biglobosa. Isolates of L. biglobosa typically are weakly virulent or avirulent and are assigned to pathogenicity group 1 (PG-1). Isolates of L. maculans are highly virulent and encompass pathogenicity groups PG-2, PG-3, and PG-4. In greenhouse tests, percent lesion/leaf area (PLLA) on cotyledons of two Brassica napus cultivars, Westar and Invigor 2153, was smaller when L. biglobosa (PG-1) was either pre- or co-inoculated at 0, 12, 24, and 48 h with virulent isolates of L. maculans in PG-2, PG-3, and PG-4. On six-leaf-stage plants of Westar, the PLLA declined significantly compared with the control when the lower leaves were treated with either PG-1 or salicylic acid, then challenged with a PG-2 isolate 24 h later. In addition, the activity of four enzymes (chitinase, β-1,3-glucanase, peroxidase, and phenylalanine ammonia lyase) was greatly enhanced at 48 and 72 h when cotyledons of Westar were inoculated first with PG-1 followed by PG-2 24 h later, compared with a water control treatment. Field experiments conducted in 2003 and 2004 showed decreased blackleg severity in plants inoculated with PG-1 alone or prior to PG-2 compared with plants inoculated with PG-2 alone or prior to PG-1.
First Report of Celery mosaic virus Infecting Celery in Venezuela
Authors: Fernández T. , Carballo O. , Zambrano K. , Romano M. , Marys E.
Published: May 2007

Celery mosaic virus (CeMV) is a significant pathogen of celery (Apium graveolens) worldwide (1). In 2005, in a produce market located in Los Salias, Miranda, celery plants with mottling and leaf malformation were noticed. Electron microscopic analysis of leaf-dip preparations from three symptomatic samples revealed flexuous viral particles that were 750 nm long. Infected cells contained pinwheel inclusions typical of those associated with potyvirus infection. Inoculation of healthy celery plants with leaf extracts from four symptomatic plants produced symptoms identical to those first observed. A survey of five produce markets in Miranda was conducted to determine the prevalence of virus infection in celery using serological and molecular analyses. Mottling and malformation of celery leaflets were observed in all the markets visited. Symptoms were noted in all five markets in each of three visits during a 3-month period. A total of 125 postharvested symptomatic plants were collected from five markets on March 29, 2005 and tested for CeMV using double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with antiserum provided by F. Rabenstein, BAX, Aschersleben, Germany. Of the 125 samples collected during the survey, 53% were ELISA positive. Twenty ELISA-positive samples were also tested using reverse transcription-polymerase chain reaction (RT-PCR) with general primers for the family Potyviridae (2). All 20 samples produced an amplicon of the expected size (1.7 kbp) after RT-PCR. Amplicons from three samples were cloned into the pCR-TOPO vector (Invitrogen, Carlsbad, CA). Sequence analysis of one clone revealed more than 98% nt to a CeMV isolate from Australia (GenBank Accession No AF203532). To our knowledge, this is the first report of CeMV in Venezuela. Our results suggest that the disease may be widely spread on celery crops growing in the areas surrounding produce markets in Miranda State.

References: (1) A. Brunt et al. Viruses of Plants. CAB International, Wallingford, Oxon, UK. 1996. (2) J. Chen et al. Arch. Virol. 146:757, 2001.
First Report of Meloidogyne mayaguensis on Angelonia angustifolia
Authors: Kaur R. , Brito J. A. , Dickson D. W. , Stanley J. D.
Published: May 2007

Angelonia angustifolia, commonly known as ‘angelonia’, belongs to the family Scrophulariaceae. This plant is an ornamental frequently grown by home gardeners in Florida. Angelonia is a short, erect perennial with smooth stems, narrow leaves with toothed margins, and long-lasting, colorful blooms that makes it an ideal summer bedding plant. Roots from angelonia plants that showed stunted growth and yellowing leaves while growing in a home garden in Alachua County were collected and sent to the Florida Department of Agriculture and Consumer Services Nematology Laboratory. The roots were heavily galled but the galls were very small. Females and second-stage juveniles (J2) were extracted from the galled roots and used for species identification on the basis of perineal patterns, J2 morphometrics, and electrophoresis of isozymes (esterase and malate dehydrogenase). Isozymes were extracted from young egg-laying females with extraction buffer (10% [wt/vol] sucrose, 2% [vol/vol] triton X-100, 0.01% [wt/vol] bromophenol blue) and resolved with polyacrylamide gel electrophoresis (4% stacking [pH 6.8] and 8% separating gel [pH 8.8] with Tris-glycine buffer) in the BioRad Mini Protean system. Morphology of the perineal patterns and measurements of the J2s matched those of the original description (3). Enzyme analyses showed two major bands (VS1-S1 phenotype) of esterase (Est) activity and one strong malate dehydrogenase (Mdh) band (N1a). The Est and Mdh phenotypes were consistent with those for M. mayaguensis reported earlier in Florida (1) and Brazil (2). Studies are currently underway regarding the identification and distribution of M. mayaguensis in ornamental nurseries and vegetable-producing areas in Florida. These surveys will provide insight for the implementation of regulatory and control measures. To our knowledge, this is the first report of A. angustifolia as a host of M. mayaguensis.

References: (1) J. A. Brito et al. J. Nematol. 36:232, 2004. (2) R. M. D. G. Carneiro et al. Nematology 2:645, 2001. (3) A. Rammah and H. Hirschmann. J. Nematol. 20:58, 1988.
Potyvirus Complexes in Sweetpotato: Occurrence in Australia, Serological and Molecular Resolution, and Analysis of the Sweet potato virus 2 (SPV2) Component
Authors: Tairo Fred , Jones Roger A. C. , Valkonen Jari P. T.
Published: May 2007

A survey for viruses in sweetpotato revealed the presence of Sweet potato virus 2 (SPV2; synonymous to Sweet potato virus Y and Ipomoea vein mosaic virus), a tentative member of the genus Potyvirus, for the first time in Australia. The SPV2-infected sweetpotato plants were also infected with strains RC and/or C of Sweet potato feathery mottle virus (SPFMV; genus Potyvirus). Five SPV2 and SPFMV isolates from Australia were sequence-characterized at the 3′ - proximal end (ca. 1.8 kb) of the genome. A simple and sensitive diagnostic procedure was devised to readily differentiate SPV2 and the two strains of SPFMV from sweetpotato plants that contained these viruses in complexes. The method involved reverse transcription with oligoT25 primer, polymerase chain reaction using a combination of degenerate primers, and restriction analysis of the 1.8-kb amplification products with HindIII and PvuII endonucleases. The Nproximal 543 nucleotides of the SPV2 coat protein-encoding sequence of the Australian isolates and 14 other isolates from Asia, Africa, Europe, and North America were subjected to phylogenetic analysis. The Australian SPV2 isolates formed a separate clade that was closest to a clade containing two North American isolates.
Response of Peanut, Pepper, Tobacco, and Tomato Cultivars to Two Biologically Distinct Isolates of Tomato spotted wilt virus
Authors: Mandal B. , Pappu H. R. , Csinos A. S. , Culbreath A. K.
Published: May 2007

Spotted wilt disease, caused by Tomato spotted wilt virus (TSWV), is an economically important disease in peanut, pepper, tobacco, and tomato in the southeastern United States. However, very little is known about the biological variability existent in the virus population. Fourteen isolates of TSWV collected in Georgia were evaluated for symptom severity. The majority of the isolates produced severe systemic necrosis. One mild (GATb-1) and one severe (GAL) isolate were further examined because of the distinct differences in their virulence and symptomatology on tobacco. GATb-1 caused a few chlorotic spots and mild systemic symptoms, whereas GAL produced a large number of local lesions and severe systemic necrosis. Distinct differences in the response of selected commercial cultivars of peanut, tobacco, and tomato to GATb-1 and GAL infection were observed. GAL was lethal to a widely grown tobacco cultivar, K326. Georgia Green, a field resistant peanut cultivar, and C11-2-39, a breeding line with the highest level of known resistance to TSWV, were more susceptible to GAL than to GATb-1. BHN 444, a newly released TSWV-resistant tomato cultivar, showed a resistant reaction, whereas Stiletto, a newly released TSWV-resistant pepper cultivar, was susceptible to both GATb-1 and GAL isolates. Information on the biological diversity of TSWV may be useful in developing more durable TSWV-resistant crops.
Effects of the Physiological Age of Bananas on Their Susceptibility to Wound Anthracnose Due to Colletotrichum musae
Authors: Chillet M. , Hubert O. , Rives M. J. , de Bellaire L. de Lapeyre
Published: May 2007

Wound anthracnose, caused by Colletotrichum musae, and early ripening are the main problems affecting the quality of export bananas (Musa AAA Cavendish) from the Caribbean. These problems generally concern bananas grown in lowland plantations during the rainy season. Three experiments were carried out to study the influence of the physiological age of bananas, calculated on the basis of mean daily temperature sums, on their susceptibility to anthracnose. Stressful growing conditions, especially soil flooding, slowed fruit growth but had no direct effect on fruit susceptibility to C. musae or on the green life. However, fruit that had accumulated lower temperature sums were less susceptible to wound anthracnose. By varying the source-sink ratio, we show that bananas of the same grade but different physiological ages had markedly different susceptibility to C. musae. Bananas with the same temperature sum accumulation but grown in different soil-climate conditions had different levels of susceptibility. Fruit grown in cooler, highland areas were less susceptible to C. musae than fruit of the same physiological age from lowland plantations. Our results suggest that temperature sum accumulation rate is a critical factor affecting the susceptibility of bananas to the pathogen.
A New Greenhouse Method to Assay Soybean Resistance to Brown Stem Rot
Authors: Tabor G. M. , Cianzio S. R. , Tylka G. L. , Roorda R. , Bronson C. R.
Published: May 2007

Greenhouse, growth chamber, and field experiments were conducted to develop a method to assess resistance of soybeans to Cadophora gregata (Phialophora gregata), causal agent of brown stem rot (BSR). In the new method, C. gregata is introduced at the base of the stems of 2-week-old soybeans, and the presence of the fungus is assessed in the tips of the stems 5 weeks later. To test the effectiveness of the method, two populations of soybeans and 10 checks were inoculated at the stem base and then assayed for fungal colonization of the stem tips, percentage of symptomatic leaflets, and percent internal stem length discolored. The lines also were planted in naturally infested fields to assess for percent internal stem length discolored, and were tested for the presence/absence of a BSR-resistant molecular marker. Greenhouse, field, and molecular marker data were compared. Linear regression analysis suggested that percentage of plants with colonized stem tips explained 41 to 64% of the variability (P < 0.0001) in percent stem length discolored in the field and 58 to 85% of the variability (P < 0.0001) in molecular marker data for BSR resistance. Percent stem length discolored assessed in the greenhouse had the lowest correlation with percent stem length discolored in the field and with the molecular marker. Of three incubation temperatures tested, 22°C was the most conducive for distinguishing resistant/susceptible soybeans using the colonization method.
Effects of Application of Fungicide During the Dormant Period on Phomopsis Cane and Leaf Spot of Grape Disease Intensity and Inoculum Production
Authors: Nita M. , Ellis M. A. , Wilson L. L. , Madden L. V.
Published: May 2007

Efficacy of application of the fungicides calcium polysulfide or fixed copper during the dormant period on control of Phomopsis cane and leaf spot of grape (Vitis spp.), caused by Phomopsis viticola, was examined under field conditions during the 2003 and 2004 growing seasons in Ohio. Dormant-period fungicide applications were made either in the fall (after leaf drop and periderm tissue formation on the first-year canes, mid-November), or spring (at bud-swell, mid-April), or both. Disease incidence and severity on leaves and internodes were examined. In addition, effects of dormant-period application on sporulation of P. viticola were determined by examining the number of conidia in rain-splashed water in the spring and formation of mature pycnidia on cane sections in the winter. Fall-and-spring and spring applications of calcium poly-sulfide provided 12 to 88% reduction in disease intensity (incidence or severity), whereas calendar-based protectant mancozeb applications reduced overall disease intensity by 47 to 100%. Fixed-copper applications did not provide a consistent reduction of the disease. Fall applications of dormant-period fungicide provided little or no effect by itself. There was a significantly lower number of conidia observed in collected splashed rain water from vines treated with fall-and-spring applications of calcium polysulfide than in rain water from nonsprayed vines. Fall-and-spring and spring applications of calcium polysulfide provided a significant reduction in the number of mature pycnidia formed on incubated cane sections compared with the nonsprayed control (5 versus 10 pycnidia/cm2), whereas fixed copper did not provide a significant reduction.
Variability Associated with Suppression of Gray Mold (Botrytis cinerea) on Geranium by Foliar Applications of Nonaerated and Aerated Compost Teas
Authors: Scheuerell Steven J. , Mahaffee Walter F.
Published: May 2007

The use of compost teas in agriculture and urban landscapes is increasing, but there is conflicting information on which methods are suitable for obtaining compost teas that suppress disease when applied to plants. Numerous compost tea production parameters (compost source, aeration, nutrient additives, production duration, and use of application adjuvants) were tested for suppressing gray mold (Botrytis cinerea) on geranium. While individual compost tea batches did significantly reduce disease, the majority of compost teas did not significantly suppress gray mold of geranium. For nonaerated compost tea (NCT), the most consistent, significant disease suppression was associated with particular compost samples and increased production time, with little effect of periodic stirring or the addition of nutrients at the onset of production. Continuously aerating compost tea did not significantly increase disease suppression compared with nonaerated compost teas. Preparing aerated compost tea (ACT) with nutrient additives did not consistently increase disease suppression; however, 67% of ACT batches made with a mixture of kelp extract, rock dust, and humic acid significantly reduced disease. Applying ACT with spray adjuvants significantly reduced disease compared with ACT with no adjuvants. The variability in gray mold suppression from NCT and ACT applications indicates that disease control would not be commercially acceptable unless there are no other alternatives due to production constraints, e.g., organic standards.
Evaluation of a Disease Warning System for Phomopsis Cane and Leaf Spot of Grape: A Field Study
Authors: Nita M. , Ellis M. A. , Wilson L. L. , Madden L. V.
Published: May 2007

A field evaluation of a warning system for Phomopsis cane and leaf spot of grape (Vitis spp.), caused by Phomopsis viticola, was conducted in Ohio over 3 years (2002 to 2004) by applying fungicides and fungicide-adjuvant combinations based on predicted infection events. Three different criteria for risk—light, moderate, and high—were evaluated with the warning system. The warning system is based on measured weather conditions (temperature and wetness duration following rain) and a model for risk of leaf and internode infection. Vines were sprayed with fungicides based on either the warning system or a calendar-based 7-day protectant program, from 2.5-cm shoot growth (Eichhorn-Lorenz [E-L] stage 7) to the end of the broom (E-L stage 27). Fungicides were tested with or without an adjuvant (JMS Stylet-Oil or Regulaid). In the controls, the mean percentage of leaves and internodes with infections ranged from 36 to 100%, the number of lesions per leaf ranged from 1 to 28, and percentage of internodes covered by lesions ranged from 1 to 12%. Both the calendar-based protectant treatment (based on use of mancozeb) and the warning system treatment based on spraying in response to light or moderate predicted infection events (especially with mancozeb + Regulaid) resulted in significantly less disease incidence and severity compared with the controls. The mean percent control (relative difference in disease between a treatment and the control) was higher for the protectant schedule (˜55% and ˜80% for incidence and severity, respectively, based on application of mancozeb) than for the warning system (˜36% and ˜60% for incidence and severity, respectively, based on application of mancozeb + Regulaid), but there were two to three times more fungicide applications with the protectant schedule than with the warning system.
First Report of Globodera rostochiensis in Mallorca Island, Spain
Authors: Andrés M. F. , Alonso R. , Alemany A.
Published: May 2007

Potato (Solanum tuberosum) is one of the most important crops in the Balearic Islands with a yield of 35,000 t in 2004, distributed in 1,100 ha and mostly located in the Sa Pobla Region of Mallorca Island. Potato cyst nematode (PCN) species are widespread in potato crop regions of the Iberian Peninsula and Canary Islands, but only Globodera pallida is known to be present in Sa Pobla (1) where it causes significant yield reductions if it is not properly managed. In the spring of 2000, goldencolored females were detected in several root samples of plant potatoes. In 2001, 2002, and 2003, soil and root samples were collected at harvest from 28 fields to identify and quantify PCN species in this area. According to the European Plant Protection Organization (EPPO) diagnostic protocol, the identification of Globodera spp. populations was based on: (i) morphological and morphometrics characteristics of cyst vulval area and stylets of second-stage juveniles; (ii) protein electrophoresis patterns by isoelectric focusing (2); and (iii) DNA analysis by random amplified polymorphic DNA polymerase chain reaction techniques (2). PCN infestation was detected in 16 potato fields sampled. Mixed populations of G. rostochiensis and G. pallida were found in 14 fields distributed all around Sa Pobla, while two fields contained only G. pallida. The proportion of G. rostochiensis in mixed populations was low, rarely exceeding 20%. The origin of G. rostochiensis introduction in Mallorca is unknown since there is no direct link with other potato-growing areas of Spain. To our knowledge, this is the first report of G. rostochiensis in the Balearics Islands. The identification of G. rostochiensis in the Sa Pobla potato-production fields is very important for the development of a successful integrated pest management (IPM) program in this region.

References: (1) M. L. Martinez-Beringola et al. Nematol. Medit. 15:183, 1987. (2) S. K. Ibrahim et al. Pest Manag. Sci. 57:1068, 2001.
Vegetative Compatibility Groups and Aggressiveness of North American Isolates of Colletotrichum coccodes, the Causal Agent of Potato Black Dot
Authors: Nitzan N. , Tsror (Lahkim) L. , Johnson D. A.
Published: May 2007

The vegetative compatibility of 123 isolates of Colletotrichum coccodes from North America (United States and Canada) originating from potato, tomato, pepper, and mint was tested using nitrate-nonutilizing (nit) mutants. The North American isolates did not anastomose with previously selected European/Israeli vegetative compatibility group (VCG) testers; therefore, eight isolates were selected as VCG testers for the North American population. The 123 isolates distributed to seven VCGs at 1.6, 1.6, 4.0, 8.1, 13.8, 19.5, and 36.6%, with 14.6% of the isolates not assigned to any of the seven VCGs. Among the North American (NA)-VCGs, the average frequency of the nit1/nit3 nit mutants was lower (P < 0.05) for isolates belonging to NA-VCG1 than for isolates belonging to the NA-VCGs 2, 3, and 5. In contrast, the frequency of NitM nit mutants did not vary (P > 0.05) among the NA-VCGs and was collectively 5.14%. The results also indicated significant (P < 0.05) differences among NA-VCGs and European/Israeli (EU/I)-VCGs regarding the frequency of nit mutants. The aggressiveness trials of the North American isolates to potato indicated that plants infected with isolates belonging to NA-VCG2 and NA-VCG5 had more (P < 0.05) sclerotia on the roots and crowns than plants infected with isolates belonging to NA-VCGs 1 and 3. The plants infected with isolates belonging to NA-VCG2 had sclerotia formed higher (P < 0.05) up the stem than the plants infected with isolates belonging to NA-VCGs 1, 3, or 5. The plants infected with isolates assigned to NA-VCG2 had more (P < 0.05) infected progeny tubers than the plants infected with isolates belonging to NA-VCGs 1, 3, or 5; and the plants infected with isolates belonging to NA-VCGs 1, 2, and 5 yielded fewer (P < 0.05) potato tubers than the noninoculated control plants. A naming system for the population of C. coccodes based on the continent source of the population, the VCG number, and the isolate's code was suggested.
Occurrence of Leveillula taurica Cleistothecia on Honey Mesquite in Southern Texas
Authors: Little C. R.
Published: May 2007

Prosopis glandulosa J. Torrey (honey mesquite) is a widespread tree that serves as an important food and cover resource for wildlife in the south plains, gulf marshes, and scrub prairies of Texas. In the fall of 2005, lower leaflets of P. glandulosa were found to be infected with the asexual reproductive structures (Oidiopsis taurica (Lév.) Salmon) of Leveillula taurica (Lév.) Arnaud in the Lower Rio Grande Valley (LRGV) of Texas. Primary conidia (69 [±2.9] × 14 [±1.1] μm) were lanceolate and apically pointed, and secondary conidia (68 [±3.0] × 16 [±1.2] μm) were obovate and cylindrical. Closer investigation revealed that some plants near the edges of mesquite thickets showed evidence of ascocarp development. Immature ascocarps were yellow and turned a dark brown as they reached maturity. Mature cleistothecia (185 [±33] μm in diameter) were often clustered in groups of 5 to 10 on leaflets and were characterized by a few mycelioid appendages. The maximum number of asci found in a cleistothecium was 28 and each ascus contained two ascospores (39 [±1.7] μm × 17 [±1.3] μm). L. taurica has been observed on Prosopis spp. (P. chilensis, P. glandulosa, and P. juliflora) in Mexico (1) and on P. chilensis in Texas (2), however, to our knowledge, this is the first report of sexual reproduction on P. glandulosa in the LRGV. The presence of sexual reproductive structures on mesquite may indicate the importance of ‘alternate’ hosts as a site for genetic recombination in this organism since the fungus is a pathogen of vegetable crops such as peppers, tomatoes, and onions.

References: (1) M. G. Alvarez. Fitofilo 71:1, 1976. (2) J. A. Stevenson. Plant Dis. Rep. 29:214, 1945.
First Report of the Causal Agent of Huanglongbing (“Candidatus Liberibacter asiaticus”) Infecting Kumquat in Taiwan
Authors: Tsai C.-H. , Su H.-J. , Liao Y.-C. , Hung T.-H.
Published: May 2007

Huanglongbing (greening) disease caused by a nonculturable, phloem-limited bacterium is a severe disease of citrus. On the basis of the influence of temperature on host symptoms and the causal agent, this disease can be categorized as Asian caused by “Candidatus Liberibacter asiaticus”, African caused by “Ca. L. africanus”, and American caused by “Ca. L. americanus”. Kumquat (Fortunella margarita (Lour.) Swingle), a member of the Rutaceae is an economically important crop for export and local consumption in Taiwan. Recently, a Huanglongbing-like disease was found on kumquat in Yilan County, the largest kumquat-producing area in northeastern Taiwan. Even though the disease has been reported on Citrus spp. from Taiwan, it has never been reported on kumquat. Symptoms of infected kumquat were mottling, yellowing, hardening, and curling of leaves followed by premature defoliation, twig dieback, decay of feeder rootlets and lateral roots, and ultimately the death of the entire plant. Typical sieve-tube-restricted bacteria were observed in kumquat cells by electron microscopy (1). In addition, psyllid-transmission tests demonstrated that the Asian psyllid (Diaphorina citri) could transmit this bacterium to healthy kumquats. Positive bud graft transmissions were obtained to F. margarita, F. japonica (Thunb.) Swingle, F. obovata Hort. ex Tanaka, Luchen sweet orange (Citrus sinensis (L.) Osb.), and Wentan pummelo (C. maxima f. sp. butan Hay.). These inoculated plants showed symptoms in 3 to 8 months, and bacteria could be detected by polymerase chain reaction (PCR) using a common primer pair that amplified a 226-bp specific DNA fragment (2). For further molecular identification, the bacterial DNA was extracted from the inoculated plants and PCR was performed by using two sets of primers selected from the 16S rRNA region (GenBank Accession No. L22532) and 16S/23S intergenic spacer region (GenBank Accession No. AB019793). The expected DNA fragments of 1,389 bp and 862 bp were, respectively, amplified from symptomatic plants but not from healthy plants. The PCR products were cloned and sequenced (GenBank Accession Nos. DQ302750 and DQ207841). The 16S rRNA has 98 to 99% identity and 16S/23S intergenic spacer region has 99% identity to the corresponding region of “Ca. L. asiaticus” in GenBank. These molecular analyses confirm the presence of “Ca. L. asiaticus” in kumquat. Since Huanglongbing has been rarely reported naturally on kumquat, further analysis of this bacterium as a special strain of “Ca. L. asiaticus” is needed.

References: (1) M. Garnier et al. Ann. Microbiol. 135A:169, 1984. (2) T. H. Hung et al. J. Phytopathol. 147:599, 1999.
First Report of Puccinia jaceae var. solstitialis Pycnia on Yellow Starthistle in the United States
Authors: Fisher A. J. , Bruckart W. L. , McMahon M. B. , Luster D. G. , Smith L.
Published: May 2007

The rust fungus Puccinia jaceae (Otth) var. solstitialis field isolate FDWSRU 84-71 (formerly TR 84–96) was first released in California for the biological control of yellow starthistle (YST; Centaurea solstitialis) in July 2003. This isolate was collected by S. S. Rosenthal in 1984, east of Yarhisar and Hafik (SIVAS), Turkey. It is macrocyclic and autoecious (1), completing its entire life cycle on YST. Observations were made in field plots west of Woodland, CA that had been inoculated on a monthly regimen between January and June of 2005. On February 22 and March 2, 2006, pycnia were observed in and around one of the plots (38°42.767′N, 121°53.732′W at an altitude of 57 m). Pycnia were yellow, flask shaped, and small (less than 100 μm in diameter), occurring in clusters on abaxial leaf surfaces or on petioles. DNA was isolated from pycnial and uredinial samples collected from the site and used for polymerase chain reaction amplification of the ITS2 region with P. jaceae specific primers. Sequences of amplicons from both samples were identical to FDWSRU 84-71 (GenBank Accession No. AF047728). Further amplification of pycnial DNA with PCR primers specific to the released P. jaceae isolate (2) produced the expected 851-bp amplicon. To our knowledge, this is the first report of pycnia from Puccinia jaceae var. solstitialis in the United States, suggesting that the YST rust is fully functional and completes its life cycle in California.

References: (1) D. B. O. Savile. Can. J. Bot. 48:1553, 1970. (2) L. F. Yourman and D. G. Luster. Biol. Control 29:73, 2004.
First Report of Phytophthora cambivora Causing Bleeding Cankers and Dieback on Beech (Fagus sylvatica) in Italy
Authors: Belisario A. , Maccaroni M. , Vettorazzo M.
Published: May 2007

European beech (Fagus sylvatica) is an important forest tree species common in northern and central Europe. In Italy, this species is typical in mountain areas over 1,000 m above sea level. In the last decade, decline and death was reported on European beech caused by several Phytophthora species (2), and P. pseudosyringae was recently reported in Italy (3). During 2004 and 2005, seven declining and dying F. sylvatica trees, older than 20 years, were observed in the Veneto Region of Italy with symptoms of bleeding cankers at the base of trunks and on branches. Cankers on the collar showed tongue-shaped necroses of the inner bark and cambium tissues. Four trees were in a public park of Mestre and three were in a forest stand in the province of Belluno. Samples were taken from declining trees, one in the park and two in the forest. Inner bark and cambium tissue pieces were cut from the canker margins, cultured on CARPBHy-agar (corn meal agar amended with 250 μg ml-1 ampicillin, 10 μg ml-1 rifampicin, 10 μg ml-1 pimaricin, 15 μg ml-1 benomyl, 50 μg ml-1 hymexazol), and incubated at 20°C. Ten morphologically similar isolates were subcultured as single hyphal tips and characterized. These isolates produced nonpapillate sporangia that were ovoid, obpyriform or ellipsoid, and exhibited predominately internal proliferation in soil extract. Hyphal swellings with outgrowths were present under those conditions. The morphological characteristics were consistent with those of P. cambivora (1). Base sequences of the ITS region of rDNA were determined for six of the isolates, and an 832-bp fragment was amplified for each isolate and that sequence was 100% homologous with sequences DQ396418 and AY880985 of P. cambivora in the NCBI database ( http://www.ncbi.nlm.nih.gov/BLAST/ ). The sequence of one isolate, ISPaVe 1950, was deposited in GenBank (Accession No. AM269752). Pathogenicity tests were conducted with 2-year-old potted beech seedlings. Inoculum of representative isolates was grown for 4 weeks on sterilized millet seeds moistened with V8 broth and added to soil at 3% (wt/vol). Control plants received sterilized inoculum only. The soil was flooded for 48 h. Inoculations were performed during May 2005 at 15 to 35°C with six replicates for the inoculated and control plants. The plants were maintained outdoors and assessed after 3 months. Wilt, root rot, and dark brown lesions at the collar developed on inoculated plants, but not on the controls. Symptoms were similar to those on naturally infected trees. The pathogen reisolated from the inoculated plants was morphologically identical to the original isolates, which confirmed P. cambivora as the causal agent. To our knowledge, this is the first report of P. cambivora on beech in Italy.

References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) T. Jung et al. Mycologist, 19:159, 2005. (3) E. Motta et al. Plant Dis. 87:1005, 2003.
First Report of Beet virus Q on Sugar Beet in Poland
Authors: Borodynko N.
Published: May 2007

The objective of this work was to determine whether Beet virus Q (BVQ), a member of the genus Pomovirus, is present in Poland. BVQ, like Beet necrotic yellow vein virus (BNYVV), is transmitted by Polymyxa betae Keskin. Earlier, BVQ was described as the Wierthe serotype of Beet soilborne virus (BSBV). Now, on the basis of its genomic properties (2), BVQ is recognized as a distinct virus species. BVQ is often found in fields where BSBV and BNYVV are present (4). During the fall of 2005, five plants of a cultivar susceptible to rhizomania (cv. Alyssa) and five resistant to rhizomania (cv. Henrietta) were collected from a field in the Wielkopolska Region of Poland, where BSBV and BNYVV had been previously identified, and tested for BVQ (1). All samples were analyzed by a double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA) with antiserum against BNYVV (Bio-Rad, Hercules, CA). Rhizomania was identified only in sugar beet samples of the susceptible variety. The same samples were then tested using a triple antibody sandwich (TAS)-ELISA with commercial antisera against BSBV/BVQ (As-0576.2) and BSBV (As-0576.1) (DSMZ, Braunschweig, Germany). Nine sugar beet plants gave positive reactions with antiserum against BSBV/BVQ and negative reactions with antiserum specific to BSBV. Total RNA extracted from roots of 10 beet samples was then tested using a multiplex reverse transcription-polymerase chain reaction (mRT-PCR) and specific primers designed to amplify a fragment of the RNA2 for BNYVV and BVQ (3). The primers specifically amplified fragments of 545 bp and 291 bp of the BNYVV and BVQ, respectively. BNYVV was detected in all five samples from susceptible sugar beet plants. The presence of BVQ was confirmed in nine of the sugar beer plants, and the RT-PCR products were sequenced. Sequence analysis of the 206-nt amplicon sequence of the Polish isolate of BVQ (GenBank Accession No. DQ309444) indicated 97% nucleotide and 94% amino acid sequence identity with the previously published sequence of BVQ (GenBank Accession No. AJ223596) (2). To my knowledge, this is the first report of the natural occurrence of BVQ on sugar beet in Poland. In Europe, it has been previously reported in Belgium, Bulgaria, France, Germany, Hungary, Italy, the Netherlands, Spain, and Sweden (3,4).

References: (1) N. Borodynko et al. Plant Dis. 90:112, 2006. (2) R. Koenig et al. J. Gen. Virol. 79:2027, 1998. (3) A. Meunier et al. Appl. Environ. Microbiol. 69:2356, 2003. (4) C. Rubies Autonell et al. Plant Dis. 90:110, 2006.
Analysis of Factors That Influence the Epidemiology of Sclerotinia minor on Peanut
Authors: Smith D. L. , Hollowell J. E. , Isleib T. G. , Shew B. B.
Published: May 2007

In North Carolina, sclerotia of Sclerotinia minor germinate myceliogenically to initiate infections on peanut. The effects of soil temperature and soil matric potential (ψM on germination and growth of S. minor have not been well characterized, and little is known about relative physiological resistance in different parts of the peanut plant. Laboratory tests examined the ability of the fungus to germinate, grow, and infect detached peanut leaflets at soil temperatures ranging from 18 to 30°C at ψM of -100, -10, and -7.2 kPa. In addition, detached pegs, leaves, main stems, and lateral branches from three peanut lines varying in field resistance were examined for resistance to infection by S. minor. Sclerotial germination was greatest at 30°C and ψM of -7.2 kPa. Final mycelial diameters decreased with decreasing ψM, whereas soil matric potential did not affect lesion development. Mycelial growth and leaflet lesion expansion were maximal at 18 or 22°C. Soil ψM did not affect leaflet infection and lesion expansion. Lesions were not observed on leaves incubated at temperatures of 29°C or above, but developed when temperatures were reduced to 18 or 22°C 2 days after inoculation. Pegs and leaflets were equally susceptible to infection and were more susceptible than either main stems or lateral branches. Results of this work, particularly the effects of temperature on S. minor, and knowledge of peanut part susceptibility has application in improving Sclerotinia blight prediction models for recommending protective fungicide applications.
Characterization of Isolates ofFusariumspp. Obtained from Asparagus in Spain
Authors: Corpas-Hervias C. , Melero-Vara J. M. , Molinero-Ruiz M. L. , Zurera-Muñoz C. , Basallote-Ureba M. J.
Published: May 2007

Microbial analysis of asparagus plants (Asparagus officinalis) obtained from four nurseries in Spain in 2002 to 2003 indicated high frequencies of Fusarium proliferatum, F. oxysporum, and F. moniliforme in the rhizomes and storage roots. Out of 201 isolates of Fusarium obtained from nursery crowns and from plants sampled in nine established asparagus fields, the highest frequency of highly pathogenic isolates was observed from samples collected from fields, and included some extremely virulent isolates of F. solani. For isolates of low to moderate virulence, the percentage of those significantly (P = 0.01) associated with root dry weight loss was larger for F. proliferatum (53.8%) than for the other Fusarium species (10.3 to 23.1%). Random amplified polymorphic DNA (RAPD) analysis of 19 isolates of Fusarium spp. grouped all F. proliferatum and F. moniliforme isolates together and, in a second cluster, five of the eight isolates of F. oxysporum. Asparagus cultivars Verde-Morado and Dariana were the least susceptible of 11 cultivars commonly grown in Spain; isolates of F. solani and F. moniliforme proved highly virulent; and a significant interaction was observed among pathogen isolates and asparagus cultivars when representative pathogenic isolates of F. proliferatum, F. oxysporum, F. moniliforme, and F. solani were tested on those cultivars. Larger reductions in root dry weight were associated with F. proliferatum and F. solani than with F. oxysporum and F. moniliforme, and differences in root and stem dry weights among cultivars were significant.
Colletotrichum acutatum Overwinters on Sweet Cherry Buds
Authors: Børve Jorunn , Stensvand Arne
Published: May 2007

Either naturally infected or artificially inoculated sweet cherry (Prunus avium) buds on fruit spurs (mainly containing generative buds) and on 1-year-old shoots (mainly containing vegetative buds) were examined for presence of Colletotrichum acutatum prior to the beginning of spring growth in each of 4 years. Artificial inoculations were made during the growing seasons preceding the bud sampling. The plant material was incubated moist for either 14 (fruit spurs) or 21 (1-year-old shoots) days at 20°C. Following moist incubation at 20°C, C. acutatum frequently sporulated on buds of fruit spurs and shoots. The fungus sporulated in orange, short-thread or hornlike structures, mainly on distal parts of the buds, and was usually easily visible with the unaided eye. The incidence of infected buds on naturally infected and inoculated fruit spurs was 2 to 80% and 38 to 79%, respectively. Incidence on naturally infected and inoculated shoots was 0 to 53% and 4 to 45%, respectively. On buds within fruit spurs, the incidence of C. acutatum was significantly higher on generative than on vegetative buds. This investigation shows that buds can host C. acutatum and thus are likely to be an important source of primary inoculum for anthracnose of sweet cherry.
First Report and High Prevalence in Noncherry Host of Cherry virus A in Italy
Authors: Barone M. , Alioto D. , Marais A. , Candresse T. , Ragozzino A.
Published: May 2007

Cherry virus A (CVA) has been reported to naturally infect sweet and sour cherry, apricot, peach, and plum but has not been associated with any symptoms. In the spring and summer of 2005, samples were collected in Prunus spp. germplasm collections in Campania (Italy) and analyzed by a polyvalent reverse transcription-polymerase chain reaction (RT-PCR) assay (1). Amplicons were sequenced, revealing CVA infection in seven apricot cultivars (Prunus armeniaca L.), one plum (Prunus domestica L.), and one cherry (Prunus avium L.). CVA sequences (GenBank Accession Nos. DQ445275 to DQ445292) compared among themselves and with databank sequences showed pairwise nucleotide sequence identity levels of 80.3 to 99.6% (86.8 to 100% for amino acid sequences), significantly extending the known variability range of CVA. The presence of CVA was confirmed by hybridization with a CVA-specific probe (P39) (2), targeting region different from that amplified in the polymerase chain reaction assay. All samples containing CVA were found to be in mixed infections with Apple chlorotic leaf spot virus (ACLSV) and Apricot pseudo-chlorotic leaf spot virus (plum, apricot), or ACLSV plus Cherry green ring mottle virus (cherry) so that CVA symptomatology could not be evaluated. To our knowledge, these results constitute the first report of the occurrence of CVA in Italy. They confirm the ability of CVA to naturally infect noncherry Prunus spp. hosts with surprisingly high prevalence levels (6 of 14 and 1 of 6 tested apricot and plum cultivars, respectively).

References: (1) X. Foissac et al. Phytopathology 95:617, 2005. (2) W. Jelkmann J. Gen. Virol. 76:2015, 1995.
Influence ofGlomus intraradiceson Black Foot Disease Caused byCylindrocarpon macrodidymumonVitis rupestrisUnder Controlled Conditions
Authors: Petit Elsa , Gubler Walter Douglas
Published: May 2007

We examined the influence of an arbuscular-mycorrhizal fungus, Glomus intraradices (INVAM CA 501), on black foot disease caused by the fungus Cylindrocarpon macrodidymum on Vitis rupestris cv. St. George under controlled conditions. Mycorrhizal or nonmycorrhizal grape rootings were inoculated with the pathogen. Eight months following inoculation with the pathogen, we evaluated disease severity, vine growth, and mycorrhizal colonization. Mycorrhizal plants developed significantly less leaf and root symptoms than nonmycorrhizal plants (P = 0.04 and P < 0.0001, respectively). Only nonmycorrhizal grape rootings inoculated with the pathogen had significantly less dry root and leaf weights compared with the noninoculated control (P = 0.0021 and P = 0.0017, respectively). Mycorrhizal colonization was high (48.3% for the noninfected control and 54.5% for plants infected with C. macrodidymum) and not significantly affected by inoculation with C. macrodidymum (P = 0.2256). Thus, V. rupestris preinoculated with G. intraradices were less susceptible to black foot disease than nonmycorrhizal plants. Results from this study suggest that preplant applications of G. intraradices may help prevent black foot disease in the nursery and in the vineyard.
Infection Potential of Pleospora allii and Evaluation of Methods for Reduction of the Overwintering Inoculum of Brown Spot of Pear
Authors: Llorente Isidre , Vilardell Albert , Montesinos Emilio
Published: May 2007

The capacity for germination and pathogenicity to pear leaves of ascospores of Pleospora allii, the teleomorph of Stemphylium vesicarium, causal agent of brown spot of pear, were studied in vitro. Most ascospores germinated within 1 h at temperatures between 15 and 20°C, and the optimum temperature for germination was 18.9°C. Infections developed on wounded and non-wounded detached pear leaves, but were more frequent on wounded leaves. The minimum infective dose was one ascospore per wound. Biological, chemical, and mechanical methods for decreasing overwintering inoculum of P. allii were evaluated. Ascospores were discharged from March to May, depending on the orchard and year. Leaf shredding or removal were the most effective methods of reducing overwintering inoculum. Biological control methods based on application of Thichodermasp. formulations were partially effective. Chemical methods based on copper and urea treatments were ineffective.
Identification and Detection of Phoma tracheiphila, Causal Agent of Citrus Mal Secco Disease, by Real-Time Polymerase Chain Reaction
Authors: Licciardello G. , Grasso F. M. , Bella P. , Cirvilleri G. , Grimaldi V. , Catara V.
Published: May 2007

Phoma tracheiphila is the causal agent of a tracheomycotic disease of citrus called mal secco causing the dieback of twigs and branches. This pathogen is of quarantine concern; therefore, fast and reliable protocols are required to detect it promptly. A specific primer pair and a dual-labeled fluorogenic probe were used in a real-time polymerase chain reaction (PCR) with the Cepheid Smart Cycler II System (Transportable Device TD configuration) to detect this fungus in citrus samples. Real-time PCR assay was compared to modified conventional PCR assay. The sensitivity of the former was evaluated by testing P. tracheiphila DNA dilutions, and the minimum amount detectable was about 500 fg, whereas the linear quantification range was within 100 ng to 1 pg. Conventional PCR sensitivity was 10 pg. Conventional and real-time PCR successfully detected the fungus in woody samples of naturally infected lemon and artificially inoculated sour orange seedlings. Nevertheless, real-time PCR was about 10- to 20-fold more sensitive than conventional PCR, and preliminary results indicate that the former technique achieves quantitative monitoring of the fungus in tissues. Simple and rapid procedures to obtain suitable DNA samples from fungal cultures and citrus woody samples for PCR assays enable diagnosis to be completed in a short time.