bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of a Phytophthora sp. Causing Asparagus Spear and Root Rot in Michigan
Authors: Saude C. , Hausbeck M. K. , Hurtado-Gonzales O. , Lamour K. H. 
Published: May 2007

In the spring of 2004, a Phytophthora sp. was isolated from asparagus (Asparagus officinalis) spears, roots, and dormant crowns from several fields in Oceana and Ingham counties in Michigan. Symptomatic spears were often curved, had water-soaked lesions slightly above or below the soil line or were shriveled at the site of infection or both. Infected storage roots had water-soaked lesions but were not soft at the lesion site. Infected crowns had fewer roots than healthy crowns. In the laboratory, plant tissues were rinsed in tap water and blotted dry. Sections from the edge of lesions were placed aseptically onto BARP (25 ppm of benomyl, 100 ppm of ampicillin, 30 ppm of rifampicin, and 100 ppm of pentachloroni-trobenzene) amended unclarified V8 juice agar and incubated at 25°C for up to 7 days. Phytophthora sp. isolates recovered from the infected material produced ovoid, nonpapillate, noncaducous sporangia and amphigy-nous oospores on isolation media. Single-sporangium cultures made for each isolate were stored long term in sterile 2-ml microcentrifuge tubes containing two 7-mm mycelial plugs, two sterile hemp seeds, and 1 ml of sterile distilled water. Sporangia produced on dilute V8 juice agar averaged 45 μm long × 26 μm wide and oospores were 25 to 30 μm in diameter. Chlamydospores were not observed. Five detached ‘Jersey Knight’ spears were inoculated with a 7-mm mycelial plug from the edge of actively growing 5-day-old cultures and incubated at 23 to 25°C for 5 to 7 days in a moist chamber. After 3 days, water-soaked lesions and shriveling and curving of the spears were visible on all inoculated spears. The pathogen was always reisolated from the lesion edge. No symptoms were observed when spears were inoculated with sterile V8 juice agar plugs. DNA was extracted from representative isolates, and the nuclear ribosomal internal transcribed spacer (ITS) region was amplified with ITS6 and ITS4 primers and sequenced. A BLAST search of the NCBI database with the ITS sequence revealed Phytophthora sp. UQ2141, Accession No. AF266795, as the closest match with 99% sequence similarity. These results, coupled with the morphological characteristics of the isolates, indicate that the Phytophthora sp. isolated from asparagus in Michigan is among the constituents of Phytophthora spp. included in the P. megasperma clade 6 (2), whose taxa are currently being reevaluated. Although a Phytophthora sp. has been described previously on asparagus (1,3), this is the first report, to our knowledge, of a Phytophthora sp. on asparagus in Michigan. The occurrence of excessive rainfall in the spring of 2004 is likely responsible for widespread disease and considerable yield losses in production fields. References: (1) P. A. Ark and J. T. Barrett. Phytopathology 28:754, 1938. (2) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (3) V. Vujanovic et al. Plant Dis. 87:447, 2003.
Southern Blight of Areca Palm (Chrysalidocarpus lutescens) Caused by Sclerotium rolfsii in California
Authors: Koike S. T. 
Published: May 2007

Areca palm (Chrysalidocarpus lutescens) is a popular ornamental palm that can be grown outdoors in mild climates and is commonly used as an indoor ornamental plant. During 2005, commercial palm producers lost significant numbers of areca palm seedlings grown in transplant trays to a crown rot disease. Initial symptoms consisted of a light brown discoloration of stems near the soil line. As disease progressed, the brown discoloration extended up the stem and down into the crown, foliage became gray green, and the entire plant then dried up and died. Extensive, white, cottony mycelium and numerous sclerotia developed externally on the lower stem, crown, attached palm seed, and surrounding peat moss medium. Mycelial growth was so extensive that the fungus often grew from one transplant tray cell, bridged across the plastic cell border, and into an adjacent transplant cell. Tan, spherical sclerotia measured approximately 1 mm in diameter. Isolations from diseased plants resulted in the recovery of the same white fungus that produced sclerotia. On the basis of sclerotia morphology and the presence of clamp connections at hyphal septa, the fungus was identified as Sclerotium rolfsii. Pathogenicity was tested by growing isolates on potato dextrose agar, drying the resulting sclerotia for 48 h, and then depositing 8 to 10 sclerotia at the base of healthy areca palm seedlings. Five isolates were tested using 40 plants per isolate. Non-inoculated controls were also included. All plants were incubated in a greenhouse at 22 to 25°C. After 2 weeks, inoculated plants began to show brown necrosis at the base of the stems; by the third week, plants began to dry up, and mycelium and sclerotia developed on the crowns. S. rolfsii was reisolated from all necrotic crown and stem tissues. Noninoculated controls did not develop any disease symptoms. To my knowledge, this is the first report of southern blight of C. lutescens in California. This disease has been reported on areca palms and other foliage plants in the southern United States and Central and South America (1). Circumstantial evidence (the disease occurred on palm seedlings that were planted in previously unused transplant trays and new peat moss rooting medium) suggests that the pathogen may have been brought in on palm seed. In the nursery, other foliage plants that are susceptible to S. rolfsii were planted in the same rooting medium but were unaffected by southern blight. Reference: (1) A. R. Chase. Compendium of Ornamental Foliage Plant Diseases. The American Phytopathological Society. St. Paul, MN, 1987.
White Mold of Houndstongue (Cynoglossum officinale) Caused by Sclerotinia sclerotiorum in Canada
Authors: Huang H. C. , Erickson R. S. , Van Hezewijk B. , De Clerck-Floate R. 
Published: May 2007

Houndstongue (Cynoglossum officinale L.) is a rangeland weed introduced into Canada from Eurasia, and it can be highly toxic to livestock feeding in pastures (3). During 2004, houndstongue plants near Creston, BC, Canada developed water-soaked lesions with white mycelia and black sclerotia on leaves and crowns. Isolations from diseased leaf tissues and sclerotia on potato dextrose agar (PDA) at 20°C for 5 to 7 days produced fungal colonies with formation of black sclerotia 5 to 10 mm in diameter. A single hyphal tip isolate from houndstongue. Ss-HT-C. was compared with a sunflower isolate of S. sclerotiorum, sun-87 (1), for morphology and pathogenicity. For apothecial production, Ss-HT-C and sun-87 were grown on PDA in petri dishes at 10°C for 10 weeks, and sclerotia produced were harvested, placed on moist vermiculite in petri dishes, and incubated at 20°C under light for 3 weeks. Mature apothecia were excised, stained with acid fuchsin, mounted on slides, and examined for asci and ascospores with a microscope. There were no morphological differences between Ss-HT-C and sun-87, each producing an ascus with eight binucleate, elliptical ascospores, measuring 4 × 10 μm (width × length), supporting the identity of Ss-HT-C as S. sclerotiorum (2,4). For pathogenicity tests of Ss-HT-C and sun-87, mycelial plugs (8 mm in diameter) were removed from the margin of colonies grown on PDA for 5 days at 20°C, and placed on leaves of C. officinale plants that were grown in a greenhouse (20 ± 4°C) to the rosette stage. Inoculated plants were covered with clear plastic bags, kept in the same greenhouse for 3 days, and the diameters of the leaf lesions developed at inoculation sites were measured. The experiment was run twice with 30 plants per isolate and five leaves per plant. Uninoculated plants covered with plastic bags were used as controls. Experiments used a completely randomized design. Results of leaf inoculations showed that Ss-HT-C and sun-87 were pathogenic to hound-stongue. There was no statistical difference between isolates or trials. The frequency of leaves with lesions was 90% for Ss-HT-C and 93% for sun-87. The mean leaf lesion diameters were 32 and 35 mm for Ss-HT-C and sun-87, respectively. Leaves of control plants remained healthy. S. sclerotiorum was reisolated from leaves with lesions, but not from controls. After 14 to 21 days, new sclerotia, 5 to 10 mm in diameter, were formed on leaves of inoculated plants. The plants eventually died. This study confirms that S. sclerotiorum is the causal agent for the disease of hound-stongue in Canada, and to our knowledge, this is the first world record of infection of this weed by S. sclerotiorum. References: (1) H. C. Huang and G. C. Kozub. Plant Prot. Bull. 31:333, 1989. (2) L. Kohn, Phytopathology 69:881, 1979. (3) J. A. Pfister et al. J. Range Manag. 45:254, 1992. (4) J. A. L. Wong and H. J. Willetts, J. Gen. Microbiol. 112:29, 1979.
First Report of Alternaria raphani Causing Black Patches on Chinese Radish During Postharvest Storage in Canada
Authors: Su X. J. , Yu H. , Zhou T. , Li X.-Z. , Gong J. , Chu C. L. 
Published: May 2007

During November of 2003, Chinese radishes (Raphanus sativus cv. Taibai) harvested in St. Catharines, Ontario and stored in less than 1°C with 98% relative humidity (RH) and 5°C with 96% RH showed symptoms of black and dark brown, irregular patches, with or without decay. The symptoms were closely associated with skin wounds and damaged root hairs. Fungal DNA was extracted from discolored skin samples peeled from a radish, and 18S rRNA genes were amplified with fungal-specific PCR primers (1) EF4f (5′-ggaagggrtgtatttattag-3′) and EF3r (5′-tcctctaaatgaccagtttg-3′). The cloned genes were sequenced using the primer EF4f and compared directly with nonredundant nucleotides in GenBank with BLAST. The results indicated that more than 75% of the fungal microflora on the diseased radish were Alternaria spp. Alternaria sp. was successfully isolated from discolored and decayed radish tissues. Morphological and molecular identification indicated that the isolated Alternaria sp. cultures belong to A. raphani, which was previously reported to cause leaf and pod blight on radish (2). For pathogenicity studies, a spore suspension (1 × 105 conidia/ml) obtained from a 4-week-old A. raphani culture was used to inoculate ‘Taibai’ Chinese radish tissues, including inner tissues and wounded and nonwounded skin. All tests were carried out at room temperature (22 to 24°C). On inner tissue and wounded skin, symptoms of dark brown-to-black patches appeared 2 days after inoculation and progressed with time. No symptoms developed on the noninoculated control or the nonwounded, inoculated treatment. A. raphani was reisolated from symptomatic tissue. Further evidence of pathogenicity was obtained by an additional inoculation and observation of symptoms. The results indicated that A. raphani was the causal agent of the black patches observed on Chinese radish, and to our knowledge, this is the first report that A. raphani could cause a postharvest disease on Chinese radish in storage. References: (1) J. D. Van Elsas et al. J. Microbiol. Methods 43:133, 2000. (2) M. S. Sangwan et al. J. Mycol. Plant Pathol. 32:125, 2002.
First Report of Sclerotinia minor on Sida spinosa in North Carolina
Authors: Hollowell J. E. , Shew B. B. 
Published: May 2007

The soilborne fungus Sclerotinia minor Jagger is a major pathogen of peanut (Arachis hypogaea L.) in North Carolina, Virginia, Oklahoma, and Texas. The pathogen attacks several winter annual weed species (1). Economic crops that are hosts to S. minor are seldom grown in rotation with peanut; therefore, its pathogenicity on weed species is of importance in understanding how inoculum densities are maintained between peanut crops. During September 2004, signs of fluffy, white mycelium, small, black sclerotia, and symptoms of bleached leaves and stems were observed on prickly sida (Sida spinosa L.) in a peanut field in Bertie County, NC. Plants of prickly sida with similar signs and symptoms were observed previously in a Chowan County, NC peanut field. Prickly sida is one of several weed species commonly found in peanut fields and rotational crops in agricultural areas of northeastern North Carolina. Cultivation and herbicides usually keep prickly sida under control in the early part of the growing season, but as the summer progresses into early fall, it can become prevalent, as was true in the two fields reported here. Symptomatic tissues were excised into 1- to 2-cm sections, rinsed in tap water, blotted dry, and placed on potato dextrose agar (PDA). The pure cultures with small, black irregular-shaped sclerotia (<2 mm) scattered abundantly over the culture surface were distinctive of S. minor. Pathogenicity was determined by inoculating stems of two symptom-free prickly sida plants with 2-day-old fungal mycelium. Mycelial agar plugs, 4 mm in diameter, were held in place with self-sticking bandaging gauze. Plants were misted, enclosed in plastic bags, and incubated at ambient temperature (24°C) on the laboratory countertop. Fluffy mycelium developed on the stems in 2 days and water-soaked leaves and bleached lesions formed within 6 days after inoculation. Following the incubation period, S. minor was reisolated from the inoculated plants. Two plants treated similarly with plugs of pure PDA remained healthy over the incubation period. The performance of Koch's postulates confirmed that prickly sida is a host of S. minor. To our knowledge, this report of S. minor on prickly sida is also the first report of a plant in the family Malvaceae as a host of S. minor (2). Reference: (1) J. E. Hollowell et al. Plant Dis. 87:197, 2003. (2) M. S. Melzer et al. Can. J. Plant Pathol. 19:272, 1997.
First Report of Beet pseudo-yellows virus on Cucurbita moschata and C. pepo in Costa Rica
Authors: Hammond R. W. , Hernandez E. , Mora F. , Ramirez P. 
Published: May 2007

In early 2004, severe yellowing and chlorosis were observed in field-grown cucurbits in Costa Rica. Symptoms resembled those of the genus Crinivirus (family Closteroviridae), and large populations of whiteflies were observed in the fields and on symptomatic plants. Although the identity of the whiteflies on the curcurbits was not determined, the greenhouse whitefly, Trialeurodes vaporariorum (Westwood) is known to be present in the region from where the samples were obtained. To identify the causal agent of the disease, leaf samples of symptomatic plants were collected from several farms. The leaf samples were dried with silica gel. Total RNA was extracted from leaf tissue of eight representative samples (two from healthy plants and six from symptomatic plants) using TRI Reagent (Molecular Research Inc., Cincinnati, OH). Reverse transcription-polymerase chain reactions (RT-PCR) containing one primer set at a time were performed using the Titan One-Tube RT-PCR kit (Roche Diagnostics Corp., Chicago IL) and primers specific for genes of cucurbit-infecting criniviruses, including the coat protein gene of Cucurbit yellow stunting disorder virus (3) and the minor coat protein gene (CPm) of Beet pseudoyellows virus (BPYV) (4). Primers specific for the heat shock protein (HSP) gene (CYHSPF 5′ GAGCGCCGCACAAGTCATC 3′ and CYHSPR 5′ TACCGCCACCAAAGTCATACATTA 3′) of Cucumber yellows virus (CYV, a strain of BPYV) (1) were designed based on published sequence data. In addition, primers specific for Cucurbit aphid-borne yellows virus (2) and melon yellowing-associated flexivirus (MYVF 5′ GGCTGGCAACATGGAAACTGA 3′ and MYVR 5′ CTGAAAAGGCGATGAACTA TTGTG 3′) were used in RT-PCR reactions. Amplified DNA fragments of 333 and 452 bp were obtained in each of two samples obtained from symptomatic plants and only in separate reactions containing BPYV and CYV primer sets, respectively. Nucleotide sequence analysis of all purified PCR products verified their identity as variants of BPYV, with 97 and 99% sequence identity with reported CPm and HSP sequences, respectively. The two samples from Cucurbita moschata Duch. (ayote or squash) and Cucurbita pepo L.(escalopini or sunburst squash) were taken from a region around Paraiso, Cartago, Costa Rica. To our knowledge, this is the first report of BPYV in Costa Rica. The economic impact on cucurbit production has not yet been determined. Studies are underway to determine the prevalence and genetic variability of BPYV isolates in Costa Rica. References: (1) S. Hartono et al. J. Gen. Virol. 84:1007, 2003. (2) M. Juarez et al. Plant Dis. 88:907, 2004. (3) L. Rubio et al. J. Gen. Virol. 82:929, 2001. (4) I. E. Tzanetakis et al. Plant Dis. 87:1398, 2003.
First Report of Sclerotinia Stem Rot and Watery Soft Rot Caused by Sclerotinia sclerotiorum on Sand Rocket (Diplotaxis tenuifolia) in Italy
Authors: Garibaldi A. , Minuto A. , Gullino M. L. 
Published: May 2007

Several species of Diplotaxis (D. tenuifolia, D. erucoides, and D. muralis), known as wild or sand rocket, are widely cultivated in Italy. Rocket is used in Mediterranean cuisine as salad, a component of packaged salad products, and as a garnish for food. In winter 2003, a severe disease was observed on D. tenuifolia grown in unheated glasshouses on commercial farms near Albenga in northern Italy. Initial symptoms included stem necrosis at the soil level and darkening of leaves. As stem necrosis progressed, infected plants wilted and died. Wilt, characterized by the presence of soft and watery tissues, occurred within a few days on young plants. The disease was extremely severe in the presence of high relative humidity and mild temperature (15°C). Necrotic tissues became covered with white mycelium that produced dark sclerotia. Diseased stem tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 ppm streptomycin sulfate. Sclerotinia sclerotiorum (1) was consistently recovered from infected stem pieces. Sclerotia observed on infected plants measured 1.23 to 3.00 × 1.40 to 5.38 mm (average 2.10 × 2.85 mm). Sclerotia produced on PDA measured 1.00 to 4.28 × 1.00 to 6.01 mm (average 2.38 × 3.23 mm). Pathogenicity of three isolates obtained from infected plants was confirmed by inoculating 30-day-old plants of D. tenuifolia grown in 18-cm-diameter pots in a glasshouse. Inoculum, 2 g per pot of wheat kernels infested with mycelium and sclerotia of each isolate, was placed on the soil surface around the base of each plant. Three replicates of five pots each were used per isolate. Noninoculated plants served as controls. The inoculation trial was repeated once. All plants were kept at temperatures ranging between 10 and 26°C (average 15°C) with an average relative humidity of 80% and were watered as needed. Inoculated plants developed symptoms of leaf yellowing within 12 days, soon followed by the appearance of white mycelium and sclerotia, and eventually wilted. Control plants remained symptomless. S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of infection of D. tenuifolia by S. sclerotiorum in Italy as well as worldwide. The disease currently has been observed in the Liguria Region but not yet in other areas where sand rocket is cultivated. The economic importance of this disease for the crop can be considered medium at the moment, but is expected to increase in the future. Reference: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 75, 1949.
First Report of the Aecial State of Melampsora larici-populina on Larix spp. in North America
Authors: Grondin J. , Bourassa M. , Hamelin R. C. 
Published: May 2007

Melampsora larici-populina Kleb. was reported for the first time in eastern North America during 2002, on Populus spp., its telial host (1). M. larici-populina, a heteroecious rust, alternates between species of Populus and Larix. Since M. larici-populina was observed again in 2003, we investigated the possibility that its basidiospores may infect larch (Larix spp.) resulting in spermogonia and aecia. Identification of Melampsora species from aeciospore morphology is difficult but urediniospores are distinctive. This is important since the native M. medusae also alternates between Populus and Larix spp. During the spring of 2004, aecia were observed on needles of exotic (Larix decidua Mill. and L. leptolepis (Siebold and Zucc.) Gordon) and indigenous (L. laricina (K. Koch)) larch in an arboretum in Lotbinière (Quebec, Canada) where M. larici-populina has previously been found. Larch needles with yellow blister-like fructifications were collected in May 2004 and fixed on top of petri plates to allow aeciospore release onto leaves of Jackii poplar (Populus balsamifera L. × P. deltoides Marsh.). After approximately 10 days, uredinia appeared on the abaxial surface of the poplar leaves. Some of the many needles collected yielded uredinia cultures on Jackii poplars. The majority of these cultures were identified as being M. larici-populina; one was M. medusae. M. larici-populina urediniospores were 32 to 48 μm long and possessed a characteristic apical bald spot. DNA was extracted from aecia and uredinia, and the internal transcribed spacer (ITS) of the ribosomal RNA gene was amplified in real-time polymerase chain reaction (PCR) by specific primers for M. medusae or M. larici-populina created from sequences (GenBank Accession Nos. AY429656 and AY429657). The 120 base pairs target fragments amplified only with the M. larici-populina specific primers with the 14 samples that were identified as M. larici-populina by morphological characteristics of the urediniospores. No PCR amplification was obtained with M. medusae primers. These results were not unexpected since larch has been previously reported as an aecial host of M. larici-populina elsewhere (2). The ability of M. larici-populina to overwinter and complete its life cycle has important consequences since it proves that it is established and can go through sexual reproduction. A complete life cycle in eastern North America may allow M. larici-populina to generate pathogenic variation that will challenge poplar breeders in this region. References: (1) L. Innes et al. Plant Dis. 88:85, 2004. (2) G. Newcombe et al. Plant Dis. 78:1218, 1994.