bluuebunny/crossref_metadata_2025 huggingface dataset:
New Polish Isolate of Pepino mosaic virus Highly Distinct from European Tomato, Peruvian, and US2 Strains
Authors: Pospieszny H. , Borodynko N.
Published: May 2007

Pepino mosaic virus (PepMV, genus Potexvirus) was first described on pepino (Solanum muricatum) in Peru during 1980. Since 1999, the virus was reported in several European countries and in North and South America as an agent of viral disease of tomato crops. In Poland in 2002, the PepMV-SW isolate that was genetically similar to European isolates (approximately 99% identity) was identified (3). In November 2005, in the western part of the Wielkopolska Region, a virus with flexuous filamentous particles approximately 500 nm long was isolated from tomato fruits exhibiting symptoms of discoloration. Crude sap from Nicotiana benthamiana leaves was used for mechanical inoculation of indicator plants. The virus caused symptoms on N. benthamiana, N. clevelandii, Datura inoxia, and Lycopersicon esculentum. Symptomless infection on N. tabacum cv. Xanthi nc, N. tabacum cv. White Burley, and N. debneyi was confirmed by back-inoculation on N. benthamiana. The virus did not infect N. glutinosa, Physalis floridana, Petunia hybrida, Capsicum annuum, Chenopodium quinoa, Cucumis sativus, or Phaseolus vulgaris. The virus was initially identified using double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with polyclonal antiserum against PepMV (DSMZ, Braunschweig, Germany). Positive serological reactions were obtained with sap from inoculated N. benthamiana, L. esculentum, and N. clevelandii plants. The serological identification was confirmed using a reverse transcription-polymerase chain reaction (RT-PCR) with primers generated from a sequence of the RNA polymerase region of an isolate of PepMV reported in the United Kingdom (1). Sequence information obtained from the amplified fragment of the virus designated PepMV-PK (GenBank Accession No. DQ387870), showed only 81% nt identity and 89% amino acid identity with PepMV-SW (GenBank Accession No. DQ387869). PepMV isolates can be divided into three strains including European tomato, Peruvian, and US2 based on their genetic diversity (2). The PepMV-PK isolate resulted in nucleotide identities ranging from 79 to 81% with isolates of the European tomato strain (GenBank Accession Nos. AJ438767, AF340024, AF484251, AJ271991, AJ606359, and AJ290424), 81% with the Peruvian strain (GenBank Accession Nos. AM109896 and AJ606361), and 78% identity with each of the U.S. isolates US1 (GenBank Accession No. AY509926) and US2 (GenBank Accession No. AY509927). These results show that the new Polish isolate is distinct from all other PepMV isolates reported to date.

References: (1) C. J. French et al. Plant Dis. 85:1121, 2001. (2) L. Pagan et al. Phytopathology 96:274, 2006. (3) H. Pospieszny et al. Phytopathol. Pol. 26:91, 2002.
First Report of Southern Blight Incited by Sclerotium rolfsii on Potato (Solanum tuberosum) in Northern Italy
Authors: Garibaldi A. , Gilardi G. , Gullino M. L.
Published: May 2007

During the summer of 2005, plants of potato (Solanum tuberosum L.) showing severe basal rot symptoms were observed in a commercial field near Alessandria (northern Italy). The first symptoms were detected during early July in correspondence with a strong increase of air temperature (as much as 38°C, with an average monthly increase of 10°C) and relative humidity. Infected plants showed dry collar rots and extensive necrosis of cortical tissues. Leaves of infected plants were chlorotic. As the disease progressed, tubers rotted and plants wilted. Infected plants appeared in patches, encompassing 10 to 15% of the cultivated area. In the presence of abundant moisture, a white mycelium occurred on infected tissues. On their surface, infected tubers showed a fan-like mycelial growth. Later, white or light-to-dark brown sclerotia (2 to 4 mm in diameter) developed from mycelium. Clamp connections were present. The diseased tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 mg/liter of streptomycin sulfate. Sclerotium rolfsii was consistently isolated from infected plants. Pathogenicity of one isolate obtained from infected plants was confirmed by inoculating healthy S. tuberosum plants (cv. Hermes) grown in 2:l volume pots (1 plant per pot, seven replicates). Inoculum that consisted of 1 g/pot of wheat kernels infested with mycelium and sclerotia was placed on the soil surface. Seven noninoculated plants served as controls. The inoculation trial was repeated once. Plants were kept at temperatures ranging between 25 and 32°C and watered as needed. Inoculated plants developed symptoms of leaf yellowing within 10 days, soon followed by the appearance of white mycelium and sclerotia and then eventually wilted. Control plants remained symptomless. Sclerotium rolfsii was reisolated from inoculated plants.Possible attacks of Sclerotium rolfsii on S. tuberosum were described as rarely occurring in southern Italy (3). The disease, detected at the moment in very few farms and on cvs. Hermes and Monalisa, was particularly severe on the last variety, causing 5 to 15% yield losses because of premature plant death and rotting of tubers. This disease has been reported in several countries such as India (1), Israel (2), and the United States of America (4).

References: (1) N. S. Bisht. Indian Phytopathol. 35:148, 1982. (2) Y. Elad et al. Soil Biol. Biochem. 16:381, 1984. (3) R. Gigante. Ital. Agric. 87:263, 1946. (4) G. F. Weber. Phytopathology, 33:615, 1943.
Introduction of the New World Squash leaf curl virus to Squash (Cucurbita pepo) in Egypt: A Potential Threat to Important Food Crops
Authors: Idris A. M. , Abdel-Salam A. , Brown J. K.
Published: May 2007

Squash plants showing leaf curling, yellow mottling, and reduced fruit set were observed in fields in Giza, Egypt in spring 2005. These particular symptoms had not been observed previously in zucchini squash plants in Egypt, but were reminiscent of those caused by begomoviruses (Geminiviridae) that are known to occur in the region, including Watermelon chlorotic stunt virus. Squash plants were heavily infested with the whitefly Bemisia tabaci (Genn.), the only known vector of begomoviruses. Total nucleic acids were isolated from symptomatic squash leaves using the cetyltrimethylammoniumbromide method, and extracts were subjected to polymerase chain reaction (PCR) analysis using two sets of PCR primers. One primer set (prAV2644 and prAC1154) was designed to amplify a fragment that contains the entire viral coat protein (Cp), while the second primer set (prBV1855 and prBC656) was designed to amplify the common region (CR) of DNA-B of begomoviruses (1). The expected size fragments were cloned and the sequence was determined for five clones each. Unexpectedly, the Cp and the CR-B fragments shared their highest nucleotide sequence (nt) identity among well-characterized begomoviruses to the bipartite Squash leaf curl virus (SLCV) native to the western United States. A third primer set (prAC344 and prAV1134) (1) was subsequently used to amplify the remainder of the putative SLCV DNA-A. The fragment was cloned and the DNA sequence was determined. Assembly of the overlapping DNA-A fragments resulted in a complete DNA-A component sequence of 2,636 nt, which is identical to the expected size of the SLCV DNA-A component (GenBank Accession No. DQ285019). Comparison with the latter sequence indicated that the Egyptian squash isolate shared 98% nt identity with SLCV. The sequence for the DNA-B fragment (1,162 nt) shared 94% nt identity with SLCV and was deposited in GenBank as Accession No. DQ285020. The high-shared nt identity with SLCV (2) from the United States suggests that this isolate, herein SLCV-EG, has been introduced into Egypt. The relatively low DNA-B nt sequence identity was a not a surprise since this component is normally less conserved even between strains of a single begomoviral species. Introduction of SLCV is not only potentially significant to the domestic production of crop species in the Cucurbitaceae but also for legume crops. SLCV has a broad host range that also includes members of the Fabaceae, which includes species that contribute significant sources of protein for much of Egypt's population. The virus thus far is thought to be present only in Lower Egypt, however, it could feasibly threaten legume and cucurbit crops if it spreads to Upper Egypt. To our knowledge, this is the first begomovirus of New World origin to become established in the Old World.

References: (1) A. M. Idris and J. K. Brown. Phytopathology 88:648, 1998. (2) S. G. Lazarowitz. Virology 180:70, 1991.
First Report of Nemesia ring necrosis virus in North America in Ornamental Plants from California
Authors: Mathews D. M. , Dodds J. A.
Published: May 2007

During the last several years, two California propagators have detected what was believed to be the tymovirus Scrophularia mottle virus (ScrMV) in several ornamental plant species on the basis of enzyme-linked immunosorbent assay (ELISA) using a ScrMV antibody system. Symptoms were generally mild, ranging from nonsymptomatic to a mild mosaic. Our laboratory confirmed the presence of a tymovirus in one Verbena sp. and two Diascia spp. cultivars on the basis of dsRNA analysis that showed bands of approximately 6,400 and 300 nucleotides representing the genomic and coat protein subgenomic RNAs, respectively. While these plants and those that were experimentally infected (Nicotiana benthamiana and N. clevelandii) also tested positive for ScrMV by ELISA, the host range did not match that published for ScrMV, notably the lack of symptoms in Chenopodium quinoa and the lack of systemic infection in Datura stramonium. A similar host range result was reported in Europe for another tymovirus that cross reacts with ScrMV antiserum, Nemesia ring necrosis virus (NeRNV) (2). Using NeRNV specific primers (1), we used reverse transcription-polymerase chain reaction (RT-PCR) to test plants that had previously tested positive for ScrMV by ELISA and had dsRNAs typical of a tymovirus. An amplicon of the appropriate size (960 bp) for NeRNV was obtained from each of five samples. Using ScrMV specific primers, the same samples failed to amplify the expected product. We have found NeRNV in three Diascia spp., one Verbena sp., and one Nemesia sp. plants in two counties in California (Riverside and San Diego). When the RT-PCR products were sequenced, they all had 99% sequence identities to NeRNV with 4 to 7 single nucleotide changes (GenBank Accession Nos. DQ648150 to DQ648154). Notably, each of the five amplicons had changes at nucleotides 5134 (G to C) and 5549 (G to T) when compared with the European isolates of NeRNV, which did not result in any amino acid changes. To our knowledge, this is the first report of NeRNV in North America and more specifically, in California.

References: (1) R. Koenig et al. J. Gen. Virol. 86:1827, 2005. (2) A. L. Skelton et al. Plant Pathol. 53:798, 2004.
Changes in the Concentration of anAllexivirusDuring the Crop Cycle of Two Garlic Cultivars
Authors: Cafrune Eva E. , Balzarini Mónica , Conci Vilma C.
Published: May 2007

Garlic can be infected by a number of viruses, including allexiviruses. The coat protein sequence of an Allexivirus was detected in Argentina and deposited in the EMBL database as Garlic mite-borne filamentous virus (accession number X98991); it has high homology with Garlic virus A (GarV-A). For reliable virus detection, plants should be sampled when virus titer is high to reduce the risk of identifying infected plants as healthy. The objective of this study was to describe fluctuations in the concentration of this Argentine isolate of GarV-A in two garlic cultivars, Morado-INTA and Nieve-INTA, throughout the crop cycle using the double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Over a 2-year period, for both cultivars, virus concentration was assessed in samples from the tips section of the youngest leaves of GarV-A-infected plants, and from basal sections of both dormant and devernalized cloves of stored bulbs of Morado-INTA. The concentration of GarV-A varied during the crop cycle, but peaked at the beginning and again at the end of the crop cycle. Virus concentration was slightly higher in devernalized cloves compared with dormant cloves of Morado-INTA. No correlation between virus concentration and mean air temperature was observed. The results of this study recommend sampling times at the beginning of the crop cycle at 64 to 81 days after planting, and towards the end of the crop cycle to evaluate for the presence of GarV-A by DAS-ELISA.
First Report of Cochliobolus sativus on Guzmania sp. in Belgium
Authors: Crepel C. , Inghelbrecht S. , Baeyen S. , Maes M.
Published: May 2007

In 2001 and again in December 2005, an outbreak of leaf spots was observed on Guzmania sp. ‘Gwendolyne’ (Bromeliaceae) in a Belgian nursery. Typical disease symptoms were irregular spots with a grayish center and a narrow red-brown margin. Identification was based on morphological characteristics and molecular techniques. Isolations of diseased leaf tissues previously washed with sterile distilled water on potato dextrose agar (PDA) resulted in mycelial colonies after 7 to 8 days. Fungal mycelium grew at a linear rate of 30.4 mm per 24 h at 21°C in the dark. The pathogen produced aerial mycelium and sporulation was abundant. The color of the colonies on PDA was pale to dark brown and conidial characteristics similar to those of Cochliobolus sativus (anamorph Bipolaris sorokiniana) (1) were observed: brown ellipsoidal spores rounded at the top, 3 to 12 distoseptate, with average dimensions of 40 to 120 × 17 to 28 μm. The pathogen was also characterized with molecular tools. DNA was isolated from mycelium from a PDA plate. The ribosomal DNA region ITS1-5.8S-ITS2 was amplified and cloned. The ITS1 sequences (174 bp) of two independent clones were analyzed. The three highest similarity scores (E = 2e-71) obtained in BLAST were C. sativus (GenBank Accession Nos. AF158105 and AF071329) and B. sorokiniana strain BS11 (GenBank Accession No. AY372677). For these, pairwise alignments resulted in an identical score of 97.1% (169 identical bases, four indels, and one transversion). The new Genbank Accession No. of the ITS1 sequence is DQ 641269. To prove pathogenicity of the isolate, inoculations were done by spraying leaves of three young Guzmania sp. ‘Gwendolyne’ plants with a 20-ml spore suspension (106 spores/ml). Three plants were sprayed with sterile distilled water as controls. The plants were kept for 48 h under a humid chamber and subsequently at room temperature (20 to 25°C) on the laboratory bench. Three to four days after inoculation, leaf spots were observed and C. sativus (anamorph B. sorokiniana) was reisolated, completing Koch's postulates successfully. On the basis of symptoms, morphological characteristics, and pathogenicity tests, the pathogen was identified as C. sativus (anamorph B. sorokiniana). To our knowledge, this is the first record of C. sativus (anamorph B. sorokiniana) on Guzmania sp. in Belgium.

References: (1) A. Sivanesan and P. Holliday. Description of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, England, UK, 1981.
Effect of Environmental Factors and Pesticides on Mycoparasitism of Sclerotinia minor by Coniothyrium minitans
Authors: Partridge D. E. , Sutton T. B. , Jordan D. L.
Published: May 2007

The effects of soil temperature and moisture, and nine pesticides commonly used in peanut production, on the mycoparasitic activity of Coniothyrium minitans on sclerotia of Sclerotinia minor were evaluated. In vitro mycelial growth and conidia germination of C. minitans were sensitive to azoxystrobin, chlorothalonil, fluazinam, pyraclostrobin, tebuconazole, and diclosulam. C. minitans survived and infected sclerotia of S. minor in the presence of azoxystrobin, chlorothalonil, diclosulam, fluazinam, flumioxazin, S-metolachlor, pendimethalin, pyraclostrobin, and tebuconazole. Mycoparasitic activity was reduced by all pesticides except S-metolachlor compared with the nontreated control. Optimum conditions for infection of sclerotia were temperatures from 14 to 22°C and soil moisture from -0.33 to -1 kPa × 102. Mycoparasitic activity of C. minitans remained high (98% sclerotia infected) at temperatures ranging from 14 to 22°C, but decreased at temperatures above 28°C. Viability of sclerotia was inversely related to the proportion infected by C. minitans (r = -0.9963, P = 0.001). Mycoparasitic activity also declined when soil moisture was greater than -1 kPa × 102 or less than -0.10 kPa × 102. These results indicate that C. minitans should not be applied when temperatures exceed 28°C, during extremes in soil moisture, or when there is a high risk of contact with pesticides before it becomes established in the soil.
Effect of Soil Application of AG3 Phosphonate on the Severity of Clubroot of Bok Choy and Cabbage Caused by Plasmodiophora brassicae
Authors: Abbasi P. A. , Lazarovits G.
Published: May 2007

Field trials were carried out to test the effect of phosphonate fungicide (AG3) on the severity of clubroot of bok choy (Brassica rapa var. chinensis) and cabbage (B. rapa var. perkinensis and B. oleracea var. capitata) in commercial Ontario muck fields with a clubroot history. Disease severity also was examined in the same infested soil under greenhouse and microplot conditions. In microplot trials with bok choy, AG3 phosphonate concentrations of 0.07 and 0.14% a.i. applied before or after planting consistently reduced clubroot severity (1-to-4 rating) by 0.8 to 1.6 when planted in May or June. However, only the 0.14% a.i. preplanting treatment was effective in trials in July and August. Postplanting drenches of 0.14% a.i. were consistently effective throughout the season. Fresh weight of bok choy was increased or not affected by phosphonate treatments. Under field conditions, one (0.07, 0.14, and 0.21% a.i.) or two (0.07% a.i.) postplant-ing drench applications of phosphonate significantly reduced the incidence of clubroot by 52 to 87% and severity by 1.7 to 2.5 on bok choy in 2004 but not in 2005. In the 2004 trial, two applications of 0.07% a.i. AG3 phosphonate reduced the severity of clubroot comparably to single applications at 0.14 and 0.21% a.i. rates. Fresh weight of bok choy was increased by 34 to 86% with all phosphonate drench treatments in both years. With cabbage, AG3 postplanting drench treatments consistently reduced the severity of clubroot (1-to-5 rating) by a range of 0.7 to 3.3 under greenhouse, microplot, and field conditions. In the greenhouse, a single drench application of 0.07 and 0.14% a.i. AG3 phosphonate 1 day after transplanting cabbage seedlings to the infested muck soil reduced clubroot severity by 2.6 to 3.3 and increased fresh weight of cabbage tops by 66 to 69%. Similar results were seen with cabbage trials under both microplot and field conditions at all AG3 postplanting drench concentrations.
Seasonal Progression, Symptom Development, and Yield Effects of Alfalfa mosaic virus Epidemics on Soybean in Wisconsin
Authors: Mueller Emily E. , Grau Craig R.
Published: May 2007

The occurrence of Alfalfa mosaic virus (AMV) has increased in Wisconsin soybean fields in conjunction with the establishment of the soybean aphid (Aphis glycines). Field studies were conducted to determine the seasonal incidence of AMV-infected plants, progression of symptom severity caused by AMV, and the effect of AMV on soybean yield and seed quality. An isolate of AMV, collected from field-grown soybean, was introduced into plots by mechanical inoculation of plants at the V1 growth stage. The goal of the experiment was to achieve an incidence of AMV-infected plants of 0, 50, and 100% in 2002, and 0, 10, 25, 50, 75, and 100% in 2003. Severity of foliar symptoms was rated, and leaf samples were collected for serological assay (enzyme-linked immunosorbent assay [ELISA]) to estimate the incidence of AMV-infected plants from growth stages VC to R5. The maximum incidence of AMV-infected plants was 49% at growth stage R5, yet detection of the virus by ELISA dropped dramatically thereafter in both years. Incidence of AMV-infected plants accounted for 53 to 67% of the variability observed for severity of foliar symptoms in 2002 and 2003, respectively. Maximum yield loss ranged from 32% in 2002 to 48% in 2003 based on the difference in yield between noninoculated plots and plots with the highest incidence of AMV-infected plants. Incidence of AMV-infected plants explained 31% of the variation in yield in 2002 and 26% in 2003. An AMV incidence of 30% or greater was required for yield loss caused by AMV. Results of this study suggest that AMV has the potential to lower soybean yield and warrants further study.
Powdery Mildew, Caused by Leveillula taurica, on Matilija Poppy in California
Authors: Koike S. T.
Published: May 2007

Romneya coulteri, known as matilija poppy or coulter's matilija poppy, is a perennial woody shrub (family Papaveraceae) that is native to southern California and northern Mexico. The plant is used in landscape settings and has the largest flowers, measuring up to 16 cm across, of any plant native to California. In August 2006, in Monterey County, CA, landscape plants of R. coulteri were found affected with a powdery mildew disease. Initial symptoms consisted of chlorotic, irregularly shaped, vein-delimited lesions. As disease progressed, grayish white sporulation was visible on lesions on adaxial and abaxial sides of affected leaves. In advanced stages of the disease, lesions expanded up to 2 cm long and the center tissue of the lesions turned necrotic. Symptoms and signs were observed on both mature and younger foliage. The small matilija poppy planting consisted of six or seven plants and all plants were affected by the disease. Epidermal strips from both sides of leaves and leaf cross sections were mounted in drops of lactophenol and aniline blue and examined with a light microscope. These preparations showed that conidiophores developed from endophytic mycelium and emerged through stomates. Conidiophores were sometimes branched and carried one or two conidia. Hyaline, single-celled conidia were dimorphic. Primary (terminal) conidia were lanceolate with distinct apical points and measured 53 to 61 × 17 to 25 μm. Secondary conidia were ellipsoid-cylindric and measured 53 to 67 × 16 to 22 μm. On the basis of these characters, the pathogen was identified as Leveillula taurica (1). Only the anamorph Oidiopsis taurica stage was observed on plants. To prove pathogenicity, diseased leaves were collected from the landscape plantings. One diseased leaf was gently rubbed against one leaf of a potted, healthy matilija poppy. Twelve leaves were inoculated in this way, and plants were kept in a humidity chamber for 48 h and then maintained in a greenhouse (24 to 26°C). After 14 days, chlorotic lesions appeared on inoculated matilija poppy leaves and sporulation of L. taurica was observed several days later. Untreated control plants did not develop powdery mildew. The experiment was repeated and the results were the same. To my knowledge, this is the first report of powdery mildew caused by L. taurica on matilija poppy. There was no indication that the disease affected the growth of the host; however, powdery mildew reduced the quality of the appearance of this ornamental plant.

Reference: (1) H. J. Boesewinkel. Bot. Rev. 46:167, 1980.
First Report of Cucumber mosaic virus in Viola hederacea in France and Italy
Authors: Cardin L. , Moury B.
Published: May 2007

Viola hederacea Labill. (Australian violet or trailing violet), family Violaceae, is native to eastern Australia and used for its ornamental quality in humid conditions, especially in terrariums. Mosaic and chlorotic ringspots associated with a mild crinkling on leaves of V. hederacea were observed in gardens in southeast France and La Mortola, Italy in 2001 and 2003, respectively. These symptoms were different from the small chlorotic spots reported in the same species in Queensland, Australia, from which a rhabdovirus was isolated (1). In samples collected from both locations, presence of Cucumber mosaic virus (CMV) was suspected on the basis of the symptoms exhibited by a range of inoculated plants (2) and the observation of isometric particles of approximately 30 nm with the electron microscope in sap preparations. This was confirmed by positive reactions with CMV polyclonal antiserum (3) in double-antibody sandwich-ELISA. Because of the viscosity of the V. hederacea extracts, 0.01% (w/v) of pectolyase in phosphate buffer was used to grind the samples and the homogenate was kept at room temperature for 2 h. In double-immunodiffusion analysis, each isolate was shown to belong to the group II of CMV. Tomato strains D and To were used as positive controls for CMV groups I and II, respectively. The virus was transmitted by aphids (Myzus persicae) in a nonpersistent manner from infected Nicotiana tabacum cv. Xanthi-nc plants to healthy Xanthi-nc plants. To determine if CMV was responsible for the symptoms observed, the French and Italian isolates were multiplied in Xanthi-nc tobacco plants after isolation from local lesions on Vigna unguiculata and mechanically inoculated to 10 plants of V. hederacea. A systemic vein clearing developed on leaves 10 days after inoculation, followed by mosaic and crinkling. CMV was detected in each plant 3 weeks after inoculation. To our knowledge, this is the first report of CMV in V. hederacea in France and Italy.

References: (1) D. H. Gowanlock and R. G. Dietzgen. Australas. Plant Pathol. 24:215, 1995. (2) L. Cardin et al. Plant Dis. 87:200, 2003. (3) J.-C. Devergne et al. Ann. Phytopathol. 10:233, 1978.
First Report of Powdery Mildew of Parsley Caused by Erysiphe heraclei in Florida
Authors: Raid R. , Miller C. , Pernezny K.
Published: May 2007

Parsley (Petroselinum crispum (Mill.) Nym. ex A.W. Hill) is an important leaf crop in the Everglades Agricultural Area of southern Florida. During the spring of 2005 and 2006, disease signs and symptoms resembling those incited by powdery mildew were observed on parsley at a commercial vegetable farm located 15 km east of Belle Glade. Symptoms consisted of leaf chlorosis, particularly in the dense lower canopy, and desiccation of affected tissue. A dense, white-to-light gray fungal growth was visible macroscopically on the surface of affected leaf tissue. Microscopic examinations revealed ectophytic hyphae with lobed appressoria and hyaline, straight conidiophores bearing single conidia. Conidia were short-cylindrical to cylindrical, measured 33 to 44 μm long and 13 to 16 μm wide, and lacked fibrosin bodies. Conidiophore foot cells were also cylindrical, straight, and measured 27 to 37 × 9 to 10 μm. Ascocarps of the teleomorph were not observed. The fungus closely matched the description of Erysiphe heraclei DC, a pathogen previously reported as attacking parsley on the U.S. West Coast (1,2). Pathogenicity was verified by inoculating adaxial leaf surfaces of 12 plants (cv. Dark Green Italian) with conidia collected from infected tissue by using a small brush. Inoculated plants and 12 noninoculated plants were lightly misted, held in a moist chamber for 48 h (22°C), and then incubated in a growth chamber for 4 weeks at 22°C with a photoperiod of 16 h. Symptoms that developed on inoculated plants were similar to those observed in the field, with no symptoms evident on the controls treated in a similar manner. To our knowledge, this is the first report of powdery mildew on parsley in Florida, even though parsley has been grown in the area for at least six decades. Noted as being somewhat unique among fungal pathogens because it favors dry rather than moist climatic conditions, it is probably no coincidence that powdery mildew was observed both years during the month of April, the height of Florida's dry season. The fact that monthly rainfall totals of 22 and 35 mm were recorded during April of 2004 and 2005, respectfully, well below the historical average of 72 mm, may have been a contributing influence. Glawe et al. (1), in issuing a first report of E. heraclei on carrots and parsley in the state of Washington and observing ascocarps on carrot tissue, mentioned the prospect of contaminated seed serving as a potential source of dissemination. Although they did not observe the teleomorph on parsley, prospects for its occurrence seem likely. With the bulk of parsley seed planted in Florida being produced in Washington, Oregon, or California, the observations reported herein may provide credence to such a hypothesis.

References: (1) D. A. Glawe et al. Online publication. doi:10.1094/PHP-2005-0114-01-HN. Plant Health Progress, 2005. (2) S. T. Koike and G. S. Saenz. Plant Dis. 78:1219, 1994.
Similarities in Seed and Aphid Transmission Among Soybean mosaic virus Isolates
Authors: Domier Leslie L. , Steinlage Todd A. , Hobbs Houston A. , Wang Yi , Herrera-Rodriguez Gabriel , Haudenshield James S. , McCoppin Nancy K. , Hartman Glen L.
Published: May 2007

Soybean mosaic virus (SMV) is an aphid- and seed-transmitted virus that infects soybean (Glycine max) plants and causes significant yield losses. Seed-borne infections are the primary sources of inoculum for SMV infections. The strain specificity of SMV transmission through seed and SMV-induced seed-coat mottling were investigated in field experiments. Six soybean plant introductions (PIs) were inoculated with eight SMV strains and isolates. Transmission of SMV through seed ranged from 0 to 43%, and isolate-by-soybean line interactions occurred in both transmission rates and percentages of mottled seeds. For example, SMV 746 was transmitted through 43% of seed in PI 229324, but was not transmitted through seed of PIs 68522, 68671, or 86449. In contrast, SMV 413 was transmitted through seed from all PIs. SMVs that were transmitted poorly by the Asian soybean aphid, Aphis glycines, also were transmitted poorly through seed. No predicted amino acid sequences within the helper-component protease or coat protein coding regions differentiated the two groups of SMV strains. The loss of aphid and seed transmissibility by repeated mechanical transmission suggests that constant selection pressure is needed to maintain the regions of the SMV genome controlling the two phenotypes from genetic drift and loss of function.
First Report of the Root-Rot Pathogen, Armillaria nabsnona, from Hawaii
Authors: Hanna J. W. , Klopfenstein N. B. , Kim M.-S.
Published: May 2007

The genus Armillaria (2) and Armillaria mellea sensu lato (3) have been reported previously from Hawaii. However, Armillaria species in Hawaii have not been previously identified by DNA sequences, compatibility tests, or other methods that distinguish currently recognized taxa. In August 2005, Armillaria rhizomorphs and mycelial bark fans were collected from two locations on the island of Hawaii. Stands in which isolates were collected showed moderate to heavy tree mortality and mycelial bark fans. Pairing tests (4) to determine vegetative compatibility groups revealed three Armillaria genets (HI-1, HI-7, and HI-9). Rhizomorphs of genet HI-1 were collected from both dead and healthy mature trees of the native 'Ohia Lehua (Metrosideros polymorpha) approximately 27 km west of Hilo, HI (approximately 19°40′49″N, 155°19′24″W, elevation 1,450 m). Rhizomorphs of HI-7 and HI-9 were collected, respectively, from dead/declining, mature, introduced Nepalese alder (Alnus nepalensis) and from an apparently healthy, mature, introduced Chinese banyan (Ficus microcarpa) in the Waipi'o Valley (approximately 20°03′29″N, 155°37′35″W, elevation 925 m). On the basis of somatic pairing tests and intergenic spacer-1 (IGS-1) nucleotide sequence identities of 99 to 100% with North American A. nabsnona (GenBank Accession No. AY509178), HI-1 (GenBank Accession No. DQ995356), HI-7 (GenBank Accession No. DQ995358), and HI-9 (GenBank Accession No. DQ995359) were identified as A. nabsnona, a pathogen of hardwoods (1). The IGS-1 sequences of A. nabsnona genets (HI-1, HI-7, and HI-9) had a greater similarity to North American collections of A. nabsnona than to the Asian A. nabsnona, even though the two introduced hosts originated from Asia. Phylogeographic studies could help determine the potential introduction and original source of A. nabsnona in Hawaii. Although A. nabsona was isolated from multiple hosts in declining stands, pathogenicity studies are needed to confirm whether this pathogen causes disease on diverse native and exotic tree species in Hawaii.

References: (1) E. Allen et al. Pages 2–7 in: Common Tree Diseases of British Columbia. Natural Resources Canada. Canadian Forest Service, Victoria, BC, Canada, 1998. (2) D. E. Hemmes and D. E. Desjardin. Pages 129 and 153 in: Mushrooms of Hawaii. Ten Speed Press, Berkeley, CA, 2002. (3) F. F. Laemmlen and R. V. Bega. Plant Dis. Rep. 58:102, 1974. (4) Y. Wu et al. USDA Forest Service Tech. Rep. R2-58, 1996.
Canavirgella banfieldii Needlecast of Pinus strobus in Michigan
Authors: Merrill W. , Wenner N. G. , O'Donnell J.
Published: May 2007

In the winter of 1995 to 1996, browning and dieback of the 1995 needle complement of Pinus strobus L., resembling needlecast caused by Canavirgella banfieldii Merrill et al. (1), was observed in Antrim County, MI. (Needle dieback = distal portions of the needles die, but short basal segments remain living and diseased needles remain attached until normal shedding of the entire complement.) Affected needles at that time had not developed ascomata, but bore spent pycnidia resembling those of C. banfieldii. About 25% of the symptomatic needles collected on 7 June 1996 bore hysterothecia of C. banfieldii in various stages of development. On wetting about 8% of these opened and released mature ascospores. Voucher specimens are in BPI and PACMA. Heretofore, C. banfieldii has been known from western North Carolina to central New York, northern Vermont, and central and eastern Maine. This is the first report of this pathogen in the Lake States, a significant extension of its known distribution, and substantiates in part our belief that this long-overlooked fungus probably occurs throughout the natural range of P. strobus.

Reference: (1) W. Merrill et al. Can. J. Bot. 74:1476, 1996.
First Report of Phytophthora infestans A2 Mating Type in Ecuador
Authors: Oyarzun P. J. , Ordoñes M. E. , Forbes G. A. , Fry W. E.
Published: May 2007

The tropical highlands of Ecuador are a genetic center for several Solanaceous species, including potato. In 1995 and 1996, severe late blight epidemics occurred in wild Solanum species, e.g., Solanum brevifolium, growing in the transitional area between the highlands and the coastal tropical lowlands near the city of Quito. Sixteen isolates of Phytophthora infestans were collected in 1995 and 36 isolates in 1996. Of these, three from 1995 and four from 1996 were A2 mating type. Extensive and systematic sampling of commercial potato and tomato in Ecuador have failed to reveal the presence of the A2 mating type (G. A. Forbes, X. M. Escobar, C. C. Ayala, J. Revelo, M. E. Ordoñez, B. A. Fry, K. Doucet, and W. E. Fry, Phytopathology, in press.). Apparently the A2 mating type reported for the first time in Ecuador is only associated with wild Solanaceous spp. Further research is required to determine the consequences of this event for management of late blight in both potato and tomato, two important field crops in the Andean highlands.
Integrated Effect of Host Plant Resistance and Fungicidal Seed Treatment on Rice Blast Control in Brazil
Authors: Filippi M. C. , Prabhu A. S.
Published: May 2007

A field experiment was conducted in two successive years at Goiânia, GO, Brazil, to study the effect of seed treatment with pyroquilon fungicide (4.0 g a.i. per kg of seed) on rice blast in cultivars that differed in their level of resistance. Leaf and panicle blast progress was monitored in the newly released, early maturing upland rice cultivar Guarani and the advanced line CNA 4136, and compared with disease progress in the susceptible commercial cultivars IAC 165 and IAC 25 in plots with treated and untreated seed. Seed treatment suppressed leaf blast until 62 and 47 days after seeding in 1987 and 1988, respectively, when averaged across cultivars. The slow blasting nature of Guarani and CNA 4136 increased the level of disease control when environmental conditions favored blast development in 1988. Under high disease pressure the correlation between leaf blast and panicle blast severity in the field plots was negative (r = -0.5, P = 0.01). Leaf blast severity at 47 days after seeding was negatively correlated to grain yield (r = -0.709, P = 0.001). Guarani exhibited an increase in grain yield over the untreated control of 28%, corresponding to 826 kg/ha.
First Report of Nematostoma artemisiae on Artemisia in the United States
Authors: Rossman A. Y. , Taylor N. J.
Published: May 2007

A fungus associated with leaf hairs of Silver King also known as Silver Wormwood (Artemisia ludoviciana Nutt. subsp. albula (Wooton) Keck) from Missouri (Crawford County, near Bourbon) was identified as the loculoascomycete Nematostoma artemisiae Syd. and P. Syd. When the fungus is present, the leaf hairs become discolored due to the numerous dark ascocarps and eventually drop off and the living leaves lose their silvery appearance, detracting from the ornamental value of the plants. Undocumented observations suggest that the fungus occurred on this host in Ohio and other states of the Midwest in 1995. N. artemisiae was described from Japan on Artemisia indica Willd. and reported once from China on that host. The type specimen was recently redescribed and illustrated by Sivanesan (1) who provided an account of the genus of which this is the type species. The uniloculate fruiting bodies of N. artemisiae are solitary, superficial to basally immersed, dark brown, globose, 120 to 160 μm in diameter, with four to 10 black setae 125 to 175 (300) μm long extending from the thickened region around the ostiole. The bitunicate, cylindrical, 8-spored asci are 50 to 65 × 7 to 9 μm and contain pale brown, broadly fusiform, smooth ascospores, 14 to 18 × 4.5 to 5.0 μm, three-septate, slightly constricted at each septum. The anamorph pycnidia are similar in appearance to the ascomycete fruiting bodies and contain hyaline, broadly spherical conidia 3 to 5 μm in diameter. The specimen has been deposited at the U.S. National Fungus Collection (BPI 749199).

Reference: (1) A. Sivanesan. Syst. Ascomycetum 6:201, 1987.
A Disease of Pearl Millet in Zimbabwe Caused by Pantoea agglomerans
Authors: Frederickson D. E. , Monyo E. S. , King S. B. , Odvody G. N.
Published: May 2007

Necrosis at the leaf tips and margins of pearl millet (Pennisetum glaucum (L.) R. Br.) was observed in 1995 in a Pseudomonas syringae resistance screening nursery near Bulawayo, Zimbabwe. Straw-colored lesions with a chlorotic edge often extended the leaf length, and were atypical of the round spots, with a brown margin, caused by P. syringae (1). Bacteria were isolated from cut lesions macerated in water by dilution streaking onto King's medium B and nutrient agar. A gram-negative, nonfluorescent, fermentative, rod-shaped bacterium, forming yellow colonies on nutrient agar was consistently observed. Three pots of 10, 2-to 3-week-old seedlings of a susceptible cultivar, 852B, were inoculated with a 108 CFU per ml suspension from cultures by misting or injection into the whorl. In three experiments, the treatment and uninoculated control were incubated at 25°C and 95% relative humidity for 48 h before transfer to the greenhouse. The original symptoms of watersoaking at leaf tips and margins were observed after 4 days. Necrotic lesions surrounded by chlorotic tissue were observed a day later. Fluorescence on King's medium B, and levan, oxidase, potato-rot, arginine dihydrolase, 2-keto gluconate, nitrate reduction, gelatin, phenylalanine deaminase, and acid from starch tests were negative. Tobacco hypersensitivity, acid from sucrose and glycerol, aesculin hydrolysis, lipase, indole production, and growth on tetrazolium chloride were positive. The identification of the pathogen to the species level as Pantoea agglomerans (Ewing and Fife 1972) Gavini et al. 1989, formerly Erwinia herbicola, was by fatty acid analysis by the International Mycological Institute (Egham, Surrey, UK). P. agglomerans was recorded as a pathogen of pearl millet in India in 1958 (2).

References: (1) G. N. Odvody and A. K. Vidaver. Sorghum Newsl. 23:134, 1980. (2) C. K. S. Rajagopalan and G. Rangaswami. Curr. Sci. 27:30, 1958.
New Hosts of Potato Y Potyvirus (PVY) Identified in the Canary Islands
Authors: Espino de Paz A. I. , Mendez Pérez P. , Jordá-Gutiérrez C.
Published: May 2007

Potato Y potyvirus (PVY) causes annual epidemics with 30 to 40% production losses in tomato crops of the Canary Islands in autumn. Two strains of the virus were diagnosed: PVY-0 and PVY-N. To identify hosts in areas where the virus is prevalent, and to establish the role of weeds in the epidemiology of this virus and its vector, plants were collected, chosen randomly and by viruslike symptom expression. Eighty-two samples of 30 plant species were tested for PVY-0 and PVY-N by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with commercial antibodies made against PVY (INGENASA, Madrid), PVY-0/C (ADGEN, Auchincruive, UK), and PVY-N (BIOREBA, Reinach, Switzerland). Twenty-five weed species were found to be infected with PVY-0 and 12 plants were identified as new hosts (1) including the following: Argyranthemum gracile, Calendula arvensis, Convolvulus althaeoides, Foeniculum vulgare, Forsskaolea angustifolia, Hedypnois cretica, Hirschfeldia incana, Malva parviflora, Patellifolia patellaris, Sonchus oleraceus, Urospermum picroides, and Lavandula canariensis. Argyranthemum gracile and Lavandula canariensis were hosts only of PVY-N strain.

References: (1) J. R. Edwarson. Fla. Agric. Exp. Stn. Monog. 5:96, 1974.
Pathogenicity of a Species of Phomopsis Causing a Shoot Blight on Peach in Georgia and Evaluation of Possible Infection Courts
Authors: Uddin W. , Stevenson K. L. , Pardo-Schultheiss R. A.
Published: May 2007

A species of Phomopsis was isolated consistently from blighted shoots of peach trees in Georgia and Alabama. Isolates of the fungus caused characteristic cankers on current season's shoots of Babygold-7 peach trees when wounded or nonwounded dormant buds, breaking buds, and natural or artificially-created leaf scars were inoculated with conidia of the fungus. Mean canker length for the isolates was 35 mm 30 days after inoculation. No disease developed on control trees. There was no significant difference between the canker length on inoculated wounded dormant buds (59 mm) and nonwounded breaking buds (54 mm). However, cankers from both sites of inoculation were significantly longer than those resulting from inoculated artificially-created leaf scars (33 mm), natural leaf scars (33 mm), and non-wounded dormant buds (30 mm). There was no significant difference in virulence among the 5 isolates of Phomopsis sp. tested, and multi-locus DNA fingerprint analysis resulted in a similarity coefficient of 0.94 among the isolates. Additionally, results of the internal transcribed spacer (ITS) regions sequence comparisons for the isolates were consistent with the multi-locus polymerase chain reaction profiles, and the nucleotide sequences of the ITS region were identical for all 5 isolates. This is the first documentation of the pathogenicity of a Phomopsis sp. associated with shoot blight of peach in Georgia. Rapid development of disease in breaking buds indicates that they may be the primary site of invasion by the fungus. Natural leaf scars and dormant buds may also serve as possible infection courts.
Distribution of Isolates of Sclerotium rolfsii Tolerant to Pentachloronitrobenzene in Texas Peanut Fields
Authors: Shim M.-Y. , Starr J. L. , Keller N. P. , Woodard K. E. , Lee T. A.
Published: May 2007

The tolerance to pentachloronitrobenzene (PCNB) of an isolate of Sclerotium rolfsii collected in 1985 was quantified, and a survey of tolerance to PCNB in 377 other isolates of the fungus collected from Texas peanut fields from 1990 through 1994 was conducted. The effective dose (ED)50 of the previously collected PCNB-tolerant isolate was 11.07 μg PCNB/ml and was more than 5-fold greater than the ED50 of PCNB-sensitive isolates. The distribution of tolerance to PCNB among all isolates was slightly skewed, with 18 of the 377 isolates identified as having greater (P ≤ 0.05) tolerance to PCNB than the standard sensitive isolate. No isolate of S. rolfsii collected during the period of 1990 to 1994 had as high an ED50 value as did the 1985 isolate, even among those isolates collected from the same field from which the 1985 isolate was collected. ED50 values of two PCNB-sensitive and five PCNB-tolerant isolates were unchanged after 15 generations on potato dextrose agar amended with 10 μg PCNB/ml or on unamended media. The PCNB-tolerant isolate collected in 1985 was less aggressive than other isolates in greenhouse and microplot tests, but no correlation was observed between ED50 values and disease incidence in these tests for other PCNB-sensitive and tolerant isolates. These data suggest that even though high levels of tolerance to PCNB can be confirmed in some isolates of S. rolfsii, this phenomenon is likely to remain a rare event.
Use of Weather Variables to Quantify Sorghum Ergot Potential in South Africa
Authors: McLaren N. W. , Flett B. C.
Published: May 2007

Quantification of resistance to ergot requires that the observed ergot severity within a sorghum line be compared with expected ergot severity (ergot potential) to compensate for differences in environmental favorability for the disease among flowering dates and seasons. The ergot potential required to induce the onset of disease is referred to as the ergot breakdown point of that line. In earlier studies, the ergot potential of a specific flowering date was defined as the mean ergot severity in all sorghum heads over all lines in the nursery which commenced flowering on that date in a genetically broad-based sorghum nursery. In this study, results of field trials enabled accurate prediction of ergot potential by using a multiple regression analysis which included three weather variables—namely, pre-flowering minimum temperature (mean of days 23 to 27 pre-flowering), mean daily maximum temperature, and mean daily maximum relative humidity (mean of days 1 to 5 post-flowering; R2 = 0.90; P = 0.91E-5). Evaluation of predicted and observed ergot severity in an independent data set gave an index of agreement of d = 0.94 and R2 = 0.84 (P = 0.106E-4), showing that ergot severity, assuming the presence of viable inoculum, can be accurately predicted. Low pre-flowering minimum temperature was associated with reduced pollen viability, which appeared to be the primary factor predisposing lines to ergot.