bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pythium spp. Infecting Hydroponically Grown Lettuce in South Africa
Authors: Labuschagne N. , Gull C. , Wehner F. C. , Botha W. J. 
Published: May 2007

Root rot and wilting of lettuce (Lactuca sativa L. var. capitata L.) commonly occur in hydroponic systems in South Africa. Plants showing stunted growth, wilt, and root rot were collected at two commercial hydroponic systems in Gauteng Province, and root segments were plated on a Pythium selective medium (1). P. irregulare and three species groups without oogonia (F, HS, and T) were identified (2). Pythium groups F, HS, and T, and P. irregulare were represented by 63, 6, 5, and 26% of the isolates, repectively. Koch's postulates were confirmed in two greenhouse experiments by inoculating 4-week-old lettuce cv. Lutetia seedlings grown in aerated nutrient solution at 21°C. Two V8 juice agar cultures of an isolate of each species or species group were blended in 500 ml of sterile water, and 166 ml of suspension was added to the nutrient solution in each of three 5-liter receptacles containing four lettuce seedlings. Control plants received sterile V8 juice agar suspension. After 4 weeks, all Pythium isolates caused root rot and reduced fresh plant weight significantly, although no wilting occurred. Symptoms were more severe with P. irregulare and Pythium group HS than with groups F and T. Compared to the control, P. irregulare reduced fresh root and shoot weight of plants by 51 and 38%, Pythium group HS by 41 and 33%, Pythium group T by 29 and 26%, and Pythium group F by 30 and 24%, respectively. References: (1) W. J. Botha and R. L. J. Coetzer. S. Afr. J. Bot. 62:196, 1996. (2) M. W. Dick. Keys to Pythium. University of Reading Press, Reading UK, 1990.
First Report of Leaf Rust of Southern High-Bush Blueberry Caused by Pucciniastrum vaccinii in Southwestern Spain
Authors: Barrau C. , de los Santos B. , Romero F. 
Published: May 2007

Leaf rust was first observed in 1997 on southern high-bush blueberry (Vaccinium corymbosum L.) cvs. Sharpblue, Gulfcoast, and Misty, in two production fields in Huelva Province of Andalucía, in southwestern Spain. Depending on environmental conditions, these cultivars may remain evergreen in this region. In early spring, when the temperature reaches 20°C, typical yellowish-orange pustules first appear on the abaxial side of older leaves and later on new leaves. Leaf lesions began as chlorotic dots and developed into necrotic spots. As much as 85% of the fruits on symptomatic bushes showed pustules on the scar area. Multiple infection cycles were possible during the growing season as urediniospores reinfect leaves at the end of summer. Disease was considered of minor importance, but defoliation occurred when spotting was severe. Urediniospores were yellowish-orange, abovoid to elliptical (15 to 26 × 10 to 20 μm), with a thick, slightly roughened wall and a central pore. Telia formed in the lower epidermis and were smooth and brown. Teliospores (7 to 10 × 12 to 15 μm) were sessile, oblong to columnar, with two or more cross walls. Urediniospore and teliospore dimensions and morphology agree with the description of P. vaccinii, (G. Wint.) (1). A pathogenicity test was carried out with 2-year-old ‘Sharpblue’ and ‘Star’ plants. Expanded leaves were sprayed with freshly collected urediniospores suspended in a 0.05% solution of Tween 20 in water; plants were covered with plastic bags for 48 h and held in a chamber at 20 to 25°C in the shade. After 10 days, yellowish-orange pustules, similar to the original symptoms, developed on 80% of inoculated leaves of ‘Sharpblue’, while ‘Star’ plants remained symptomless. Leaf rust has not been reported on Ericaceae in Spain. The evergreen state of some southern high-bush cultivars in this area could allow the pathogen to overwinter as urediniospores. To our knowledge, this is the first report of P. vaccinii on blueberry plants in Spain. Reference: (1) P. R. Bristow and A. W. Stretch. Pages 20–22 in: Compendium of Blueberry and Cranberry Diseases. F. L. Caruso and D. C. Ramsdell, eds. American Phytopathological Society, St. Paul, MN, 1995.
Botrytis porri in Onion Seed Crops and Onion Seed
Authors: du Toit L. J. , Derie M. L. , Hsiang T. , Pelter G. Q. 
Published: May 2007

Nine fields direct-seeded with onion (Allium cepa L.) were surveyed in central Washington in the spring and summer of 2001 for Botrytis species associated with onion seed crops produced in this semiarid region. Forty plants were sampled from each field in a ‘W’ pattern in April, and 20 plants were similarly sampled from each field in June and July. Each plant was placed in a separate plastic bag, stored at 4 ± 2°C for 3 to 5 weeks, sliced lengthwise using a knife sterilized with 70% ethyl alcohol, incubated in a moist chamber for 5 days, and examined under a dissecting microscope. Fungal growth resembling Botrytis spp. was transferred to acidified potato dextrose agar (PDA) for species identification based on colony morphology, rate of growth, and spore and sclerotium characteristics (3). Cultures were incubated on a laboratory bench at 24 ± 4°C with 8 to 16 h of daylight. A species resembling B. porri (3) was detected in 3 fields in April at an incidence ranging from 3 to 28%, and in 2 of the same 3 fields in each of June and July at incidences ranging from 5 to 10%. Infected plants were asymptomatic at the time of sampling. The isolates formed brown, cerebriform sclerotia and sporulated sparsely. Subsamples of seed harvested from each field were assayed for Botrytis spp. To detect internal infection, 400 seeds from each of the nine fields were soaked in 0.525% NaOCl for 60 s, triple-rinsed in sterile deionized water, air dried, placed on a selective agar medium (2) with 20 seed per 9-cm-diameter petri plate, and incubated at 24°C (12 h day/night) for 14 days. Seeds were examined 5, 10, and 14 days after plating, and fungi resembling Botrytis spp. were transferred to acidified PDA for species determination. Isolates resembling B. porri were detected in 0.75% of seed from two of the three fields in which this species was isolated from plant samples. The internal transcribed spacer 1 region of ribosomal DNA of four isolates of the putative B. porri (two from plant samples and two from seed) were sequenced, and all four sequences matched that of B. porri registered in GenBank (Accession No. Z99666) most closely. Botrytis porri is a pathogen of garlic (A. sativum L.), leek (A. porrum L.), and wild garlic (A. vineale L.), but can infect onion and shallot (A. ascalonicum L.) when inoculated on these hosts (1). To our knowledge, this is the first report of natural infection of onion by B. porri, and the first report of seedborne B. porri on onion. References: (1) W. R. Jarvis. Pathology. Page 62 in: Botryotinia and Botrytis Species: Taxonomy, Physiology, and Pathogenicity. Canada Department of Agriculture, Monograph No. 15, 1977. (2) G. Kritzman and D. Netzer. Phytoparasitica 6:3, 1978. (3) A. H. Presly. Plant Pathol. 34:422, 1985.
First Report of Pestalotiopsis funerea on Cupressocyparis leylandii in Italy
Authors: Gonthier P. , Nicolotti G. 
Published: May 2007

Pestalotiopsis funerea (Desm.) Steyaert occurs worldwide and is reported as an opportunistic invader of conifers. It can also be have as a primary pathogen. During the spring of 2001, leaf yellowing was observed on mature and young Cupressocyparis leylandii trees in some nurseries in northern Italy. Symptoms were first observed on twig tips and progressed toward the stem during the summer, resulting in twig dieback and death of branches up to 15 mm. Dark acervuli were present in the cankers. Isolations were made from cankers and necrotic twigs by removing the outer tissue and placing wood slivers from affected tissues on potato dextrose agar. P. funerea was isolated from 88 and 72% of cankers and necrotic twigs, respectively. Four isolates were selected for inoculation tests. Inoculations were made in September on the upper part of stems of 4-year-old pot-grown C. leylandii saplings. The outer layer of the bark (5 × 3 mm) was removed, and a 5-mm-diameter mycelial plug on malt extract agar (MEA) was placed on the wound and covered with Parafilm. Sterile MEA plugs served as controls. The experiment included 20 replications for each isolate and the control. After 4 weeks, 80% of inoculated plants showed bark necrosis or small cankers, or both, and 20% died. P. funerea was reisolated. No cankers developed in the controls. P. funerea was previously reported in Italy on Thuja orientalis L. (2) and from France on C. leylandii (1), but to our knowledge, this is the first report of the pathogen on C. leylandii in Italy. References: (1) M. Morelet. Rev. Hortic. 227:35, 1982. (2) A. Panconesi and G. Vettori. Inf. Fitopatol. 5:37, 1994.
First Report of Orchid fleck virus in Costa Rica
Authors: Freitas-Astúa Juliana , Moreira Lisela , Rivera Carmen , Rodríguez Carlos M. , Kitajima Elliot W. 
Published: May 2007

Orchid fleck virus (OFV), a tentative member of the family Rhabdoviridae, infects orchids in several countries. The virus is vectored worldwide by the mite Brevipalpus californicus (Banks) (Acari: Tenuipalpidae). Eleven plants of Oncidium spp. and one plant each of the genera Cymbidium and Maxillaria exhibiting numerous yellow flecks and necrotic ringspot lesions on leaves were collected in two private orchid collections in Costa Rica. Presence of OFV was assessed by plate-trapped antigen enzyme-linked immunosorbent assay (PTA-ELISA) using an antiserum developed against an OFV isolate in Japan (2), analyses of ultrathin sections of the host cell with transmission electron microscopy (TEM), and reverse transcription-polymerase chain reaction (RT-PCR) amplification using specific primers for the viral nucleocapsid gene (1). Eight of eleven Oncidium samples, and both Cymbidium and Maxillaria samples tested positive for OFV with PTA-ELISA having A405 values ranging from 3.9 to 14.6 times higher than negative controls. Thin sections from individual samples of Cymbidium, Oncidium, and Maxillaria revealed electron-lucent intranuclear viroplasm and short, rodlike particles (40 to 50 × 100 nm) in the nucleus or cytoplasm typical of OFV-infected cells. RT-PCR amplifications from one sample of each genera resulted in PCR-product bands of approximately 800 bp. The Cymbidium RT-PCR product was cloned into a pGEM-T-Easy expression vector and sequenced using an ABI 3700 sequencer. The 619-bp nucleocapsid gene consensus sequence had 98% homology with the OFV isolate 0023 identified in Germany (GenBank Accession No. AF343870) (1). However, it had only approximately 85% nucleocapsid gene homology with other OFV isolates available through GenBank, including those from countries geographically closer to Costa Rica, such as Brazil (1). To our knowledge, this is the first report of OFV infecting orchids in Costa Rica. References: (1) A. L. Blanchfield et al. J. Phytopathol. 149:713, 2001. (2) H. Kondo et al. Bull. Res. Inst. Bioresour. Okayama Univ. 4:149, 1996.
Characterization of Powdery Mildew Caused by Leveillula taurica on Calla Lily in California
Authors: Koike S. T. , Beckman P. 
Published: May 2007

Spring calla lily (Zantedeschia spp.), also known as colored or miniature calla, has markedly increased in popularity in recent years, and the production acreage in the central coast counties of California (Monterey, Santa Cruz, and San Benito), therefore, has significantly increased. Commercial plantings of calla lily (Z. albo maculata and Z. rehmannii hybrids) in California have been infected with a powdery mildew for several years, with the disease particularly evident in late summer and fall. In 2001, powdery mildew was again prevalent, and the pathogen was examined in detail. Initial symptoms consisted of chlorotic, circular-to-oval leaf lesions with diffuse margins. As the disease progressed, white sporulation became visible on lesions. In advanced stages of the disease, the center tissue of lesions turned necrotic. For any such lesion, both the corresponding adaxial and abaxial sides of the leaf always exhibited the symptoms of the disease and developed sporulation of the pathogen. 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 epiphytic mycelium was absent and all conidiophores developed from endophytic mycelium and emerged through stomata. Conidiophores carried single or sometimes two conidia and were sometimes branched. Hyaline, single-celled conidia were dimorphic. Primary (terminal) conidia were lanceolate with distinct apical points and measured (58-) 67 to 78 (-81) × 14 to 22 μm. Secondary conidia were ellipsoid-cylindric and measured (56-) 58 to 72 × 17 to 22 μm. For both conidial types, length to width ratios were greater than three. Based on these characters, the pathogen was identified as Leveillula taurica (anamorph Oidiopsis taurica). Cleistothecia were not observed. To test whether the calla lily pathogen could infect another known host of L. taurica, diseased calla lily leaves were gently pressed against leaves of potted tomato (Lycopersicon esculentum) plants (2). Inoculated tomato plants were kept in a humidity chamber for 48 h and maintained in a greenhouse (24 to 26°C). After 12 days, chlorotic lesions appeared on inoculated tomato leaves, and sporulation of L. taurica was observed on the lesions. Uninoculated control tomato plants did not develop powdery mildew. To our knowledge, this is the first report of powdery mildew, caused by L. taurica, on calla lily in North America. This disease has been reported on calla lily in South Africa, Spain, Taiwan, Turkey, and Zimbabwe (1,3,4). References: (1) Y.-K. Chen et al. Ann. Phytopathol. Soc. Jpn. 62:580, 1996. (2) J. C. Correll et al. Plant Dis. 71:248, 1987. (3) K. A. Hirata. Host Range and Geographic Distribution of the Powdery Mildew Fungi. Japan Scientific Society Press, Tokyo, 1986. (4) E. Sezgin et al. J. Turkish Phytopathol. 13:111, 1984.
First Report of Beet soil-borne virus on Sugar Beet in Iran
Authors: Farzadfar Sh. , Pourrahim R. , Golnaraghi A. R. , Shahraeen N. 
Published: May 2007

Sugar beet is a main field crop in Iran and is cultivated in 186,000 ha. During the summer of 2001, sugar beet (Beta vulgaris) plants with pale, often upright, narrow, and rolled leaves were collected from the six main beet cultivation provinces of Iran (Fars, Ghazvin, Kermanshah, Khorasan, Semnan, and Isfahan). Roots of symptomatic plants were small, often with constriction, and exhibited warty outgrowth, proliferation of fibrous roots, and vascular necrosis. Beet soil-borne virus (BSBV) and Beet necrotic yellow vein (BNYVV, genus Benyvirus) were detected in sugar beet root samples by tissue-blot immunoassay (TBIA) using BSBV- and BNYVV-specific monoclonal antibodies (As-0576.1 and As-0799.1/CG6-F4, respectively; DSMZ Plant Virus Collection, Germany). Root extracts of sugar beet plants infected with BSBV, were infective by mechanical inoculation to Chenopodium quinoa causing necrotic ring spots. BSBV was detected in inoculated plants by TBIA. Laboratory tests using TBIA on 2,387 randomly collected samples showed that BSBV was present in 406 plants (17%) and BNYVV was present in 1,347 plants (56.43%). BSBV resembles BNYVV, the causal agent of sugar beet rhizomania, morphologically and in its transmission by Polymyxa betae (1). BNYVV has been reported previously from Iran (2). To our knowledge, this is the first report of BSBV occurring on sugar beet in Iran. References: (1) M. Ivanovic and I. Macfarlane. Annu. Rep. Rothamsted Exp. Stn. Page 190, 1982. (2) K. Izadpanah et al. Iran. J. Plant Pathol. 32:155, 1996.
Occurrence of Bacterial Stripe of Pearl Millet in Georgia
Authors: Gitaitis R. , Wilson J. , Walcott R. , Sanders H. , Hanna W. 
Published: May 2007

Bacterial stripe, caused by Acidovorax avenae subsp. avenae, was observed on breeding lines of pearl millet (Pennisetum glaucum (L.) R. Br.) in Georgia in 1999 and 2001. A gram-negative, oxidase-positive, rod-shaped bacterium that produced circular, cream-colored, nonfluorescent, butyrous colonies with entire margins on King's medium B was consistently isolated from leaf lesions. The bacterium was identified as A. avenae subsp. avenae by gas-chromatography of extracted, whole-cell, fatty acid methyl esters using the Sherlock Microbial Identification System (MIDI, Newark, DE) and by substrate utilization patterns using the Biolog Identification System (Biolog Inc., Hayward, CA). Isolates from pearl millet produced amplicons of expected size (360 bp) from 16S rDNA after conducting polymerase chain reaction (PCR) with primers WFB1 and WFB2, which are specific for A. avenae. When bacterial suspensions of 1 × 108 CFU/ml were infiltrated into the intercellular spaces of leaves of pearl millet seedlings in the greenhouse, typical water-soaked, reddish-brown stripes developed and were identical to those observed in the field. In contrast to previous reports (1), the pearl millet strains produced atypical symptoms on sweet corn (cvs. Merit and Primetime). Necroses were restricted, lacked customary water-soaking, and were similar to symptoms produced by the watermelon pathogen, A. avenae subsp. citrulli, which was used as a negative control. In contrast, three strains of A. avenae subsp. avenae previously isolated from corn in Georgia produced typical water-soaked stripes in both millet and the sweet corn ‘Merit’. However, like the millet strains, A. avenae subsp. avenae strains from corn produced atypical symptoms on the sweet corn ‘Primetime’. Using immunomagnetic separation and PCR (2), A. avenae subsp. avenae was detected in remaining samples of pearl millet seed planted in Georgia in 2001, as well as in remnant samples of seed sent to Puerto Rico for increase in 2000. The A. avenae subsp. avenae strain recovered from seed was identified by the methods listed above, and in the greenhouse it was identified by the production of typical water-soaked stripes after inoculation of pearl millet. This is the first report of A. avenae subsp. avenae infecting pearl millet in the United States. The detection and distribution of seedborne inoculum in breeding lines is significant since the program at Tifton represents a major effort by the U.S. Department of Agriculture to develop higher-yielding, disease-resistant pearl millet hybrids. Furthermore, the strains from pearl millet appear to be different from previous A. avenae subsp. avenae strains isolated from corn in Georgia, because they did not produce typical disease symptoms when infiltrated in corn leaves. References: (1) L. E. Claflin et al. Plant Dis. 73:1010, 1989. (2) R. R. Walcott and R. D. Gitaitis. Plant Dis. 84:470, 2000.
First Report of Peanut stunt virus in Perennial Peanut in North Florida and Southern Georgia
Authors: Blount A. R. , Pittman R. N. , Smith B. A. , Morgan R. N. , Dankers W. , Sprenkel R. K. , Momol M. T. 
Published: May 2007

In spring 2001, symptoms similar to aphid-vectored peanut stunt disease caused by Peanut stunt virus (PSV) were observed on perennial peanut (Arachis glabrata) cv. Floragraze in Jackson and Gulf counties, FL and Lowndes County, GA. Symptoms observed in commercial hay fields and at the North Florida Research and Education Center in Marianna and Quincy included malformed leaves, plant chlorosis, leaf mottling, and stunted plants, which resulted in reduced foliage yield. Leaf symptoms were visible throughout the growing season. Stunting was more common in spring and early summer. No symptoms were seen on rhizomes. Diagnosis of PSV (genus Cucumovirus) from symptomatic leaves and rhizome materials of 12 plants was confirmed by a direct antigen-coated enzyme-linked immunosorbent assay (DAC-ELISA). ELISA tests were repeated three times. Antibodies specific to the Clemson isolate, serotype E, were obtained from Clemson University, Clemson, SC. DAC-ELISA (1) values of 0.1 A405 above the healthy control for perennial peanut were considered positive for foliage and rhizome material tested. ELISA values ranged from 0.4 to 2.1. The mean ELISA value of the positive controls was 2.65. Symptomatic plants were also tested with ELISA using available antibodies from Agdia Inc., Elkart, IN, for Tomato spotted wilt virus, from ATCC for Peanut stripe virus, and from Clemson University (Cowpea isolate) for Cucumber mosaic virus, but all results were negative. To our knowledge, this is the first report of PSV on perennial peanut in Florida and southern Georgia. At this time, it is not known what role perennial peanut may play as a reservoir of the virus in the vicinity of peanut fields. Little is known about the potential for forage production loss and stand longevity. Next season, molecular detection techniques and epidemiological studies on peanut and perennial peanut will be conducted to ascertain the incidence and possible impact of PSV in Georgia and Florida. Reference: (1) A. G. Gillaspie, Jr. et al. Plant Dis. 79:388, 1995.
First Report of Mixed Infection of Hop stunt viroid and Peach latent mosaic viroid on Peach
Authors: Tessitori M. , Reina A. , Rosa R. La 
Published: May 2007

Hop stunt viroid (HSVd), belonging to the family Pospiviroidae, was first reported in hop, but infects several plant species, including herbaceous and woody hosts (e.g., grapevine, pear, peach, plum [2], apricot, almond, and pomegranate). In grapevine and apricot, the viroid appears to be latent. However, in other species, the viroid is associated with specific disorders: hop stunt, dapple fruit disease of plum and peach (2), and citrus cachexia. During spring 2000, stunted trees exhibiting delayed budbreak were observed in peach, cv. Redhaven, orchards in Sicily. In the summer of 2000, peach leaves were collected from symptomatic trees, triturated, and used to purify total nucleic acids by phenol extraction followed by CF-11 cellulose-chromatography. Viroid RNAs were detected by sequential polyacrylamide gel electrophoresis (sPAGE) and silver staining. Citrus exocortis viroid (371 nt) and Citrus viroid IIIb (294 nt) were used as standards. Nonradioactive hybridizations with digoxigenin (DIG)-labeled, Peach latent mosaic viroid (PLMVd) and HSVd RNA probes were used in viroid detection and identification. Predicted sizes of the viroid RNAs calculated in sPAGE and DIG probe hybridization demonstrated that ‘Redhaven’ peach trees were infected with PLMVd and HSVd. These results provide the first evidence of the contemporary presence of HSVd and PLMVd in peach trees. To our knowledge, this is the first report of HSVd in peach trees in Italy. Molecular characterization of this HSVd isolate is in progress to determine the nucleotide sequence of some of the variants in the population and to decide to which of the five proposed HSVd groups (1) this isolate should be assigned. Reference: (1) S. A. Kofalvi et al. J. Gen. Virol. 78:3177, 1997. (2) T. Sano et al. J. Gen. Virol. 70:1311, 1989.