bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coniothyrium minitans on Apothecia of Sclerotinia trifoliorum
Authors: Wang L. , Vincelli P. 
Published: May 2007

During a study of apothecial dynamics of Sclerotinia trifoliorum at the University of Kentucky Spindletop Farm at Lexington, an apothecium with small black patches on the surface of the hymenium was found. The affected apothecium was incubated in a moist chamber at room temperature. After 3 days, white, cottony mycelium was observed on the surface of the hymenium; pycnidia formed in the mycelium and around the stipe of the apothecium several days later. The apothecium eventually decayed and shrunk. Pycnidia measured 168 to 520 μm (mean 311 μm). Pycnidiospores were dark brown en masse; they were ovoid to ellipsoid, measuring 3.1 to 8.2 μm (mean 6.0 μm) in length and 3.1 to 4.1 μm (mean 3.7 μm) in width, and were faintly verrucose. Fresh sclerotia of S. trifoliorum were produced in vitro and then inoculated with pycnidiospores produced on potato dextrose agar. Inoculated sclerotia were incubated in a moist chamber at room temperature. After 7 to 10 days, inoculated sclerotia shriveled and decayed, pycnidia formed on their surfaces, and the same fungus was isolated. The fungus was identified as Coniothyrium minitans Campbell. Among 58 apothecia examined in the field on 1 November, three were apparently parasitized; pycnidia developed on one of these following a 3-day incubation. Weather conditions during the preceding 2 weeks had been generally humid with above-normal temperatures (daily mean air temperature range and interquartile range were 4.0 to 20.0 and 8.9 to 16.1°C, respectively), which may have favored activity of the mycoparasite. C. minitans was reported by Campbell (1) in California on sclerotia formed in cultures of Sclerotinia sclerotiorum. It causes decay of sclerotia of several Sclerotinia spp., some Botrytis spp., and Sclerotium cepivorum in soil. Consequently, it may have considerable biological control potential. It has been recorded in 29 countries and on all continents except South America (2). The fungus previously has been isolated from only sclerotia or, in a few instances, directly from soil. This is the first report on C. minitans parasitic on apothecia collected from the field. References: (1) W. A. Campbell. Mycologia 39:190, 1947. (2) C. Sandys-Winsch et al. Mycol. Res. 97:1175, 1993.
Thyronectria balsamea on Abies fraseri in Pennsylvania and North Carolina
Authors: Wenner N. G. , Merrill W. , Moody J. T. 
Published: May 2007

In August 1996, several 4- to 6-m-tall Abies fraseri (Pursh) Poir. in Adams County, PA, were found bearing numerous dead branches and/or dead tops. The trees had been severely stressed by being ball-and-burlapped and replanted in 1993. Distinct cankers occurred between the living and dead portions of stems and branches. Associated with these cankers were abundant, reddish-orange, erumpent stroma, each bearing three to 10 similarly colored cupulate ascomata. The latter contained asci bearing two to four large, muriform ascospores that, as they matured, formed large numbers of small ascoconidia, indicating the pathogen was Thyronectria balsamea (Cooke & Peck) Seeler (= Nectria balsamea Cooke & Peck). In September 1996, cankered dead stems and branches from affected A. frasrei Christmas tree plantations in Avery County, NC, were found bearing the same pathogen. This fungus is known on A. bal-samea (L.) Mill. from northern Minnesota east through Canada to northern New York and Newfoundland (2). Funk (1) reported it from A. lasio-carpa (Hook.) Nutt. in (presumably) British Columbia, but gave no details. This is the first report of it in the eastern United States south of northern New York, a considerable extension of its known range, and the first report of it from A. fraseri. Voucher specimens are in PACMA (Pennsylvania State University Mycologica Herbarium, Mont Alto Campus). References: (1) A. Funk. Can. For. Serv. BC-X-222:142, 1981. (2) E. V. Seeler, Jr. J. Arnold Arbor. 21:442, 1940.
Evidence for the Association of a Bipartite Geminivirus with Tomato Leaf Curl Disease in Pakistan
Authors: Mansoor S. , Khan S. H. , Saeed M. , Bashir A. , Zafar Y. , Malik K. A. , Markham P. G. 
Published: May 2007

Tomato leaf curl disease is the most important constraint on tomato production in Pakistan, where it is found throughout the country. The disease, which occurs in high incidence in Punjab and Sindh provinces, causes 30 to 40% yield losses in the spring crop and uneconomically high losses when grown as an autumn crop. The symptoms of the disease include upward or downward leaf curling, vein thickening, and stunting of the plant. The disease is transmitted by Bemisia tabaci whiteflies (non-B, biotype K) and is suspected to be caused by a geminivirus. For the detection of geminivirus, total DNA was extracted from infected plants, fractionated in an agarose gel, transferred to a nylon membrane, and Southern blotted. A full-length clone of DNA-A of cotton leaf curl virus from Pakistan (S. Mansoor, I. Bedford, M. S. Pinner, A. Bashir, R. Briddon, J. Stanley, Y. Zafar, K. A. Malik, and P. G. Markham, unpublished) was labeled with [32P]dCTP by the oligo-labeling method and hybridized at medium stringency. Geminivirus DNA forms that are normally found in infected plants were detected in plants with tomato leaf curl disease but not in healthy plants. To further confirm the presence of a whiteflytransmitted geminivirus, universal primers for dicot-infecting geminiviruses (1) were used in polymerase chain reaction (PCR) and a product of expected size (approximately 2.7 kb) was detected. The 2.7-kb PCR-amplified DNA from diseased tomato plants was labeled with [32P]dCTP and used as probe in Southern hybridization. This probe also detected geminivirus DNA forms at medium stringency. Both monopartite and bipartite geminiviruses transmitted by whiteflies have been reported to cause leaf curl symptoms on tomato from the Eastern hemisphere. Degenerate primers (PBLv2040 and PCRc1), which amplify B component DNA, were used to determine if tomato leaf curl was monopartite or bipartite (2). A product of expected size (0.65 kb) was amplified, suggesting this virus to be bipartite. DNA-B PCR product obtained from diseased tomato plants was hybridized as described above and detected geminivirus DNA forms at medium stringency. Samples of diseased tomato plants were collected from tomato fields throughout Punjab. DNA-A was detected in all 20 samples whereas DNA B was detected in 17 samples when hybridized by dot blot method at medium stringency. Our data show that tomato leaf curl virus from Pakistan is a bipartite geminivirus. This is the first evidence for a bipartite geminivirus in tomato plants from Pakistan. References: (1) R. W. Briddon and P. G. Markham. Mol. Biotechnol. 1:202, 1993. (2) M. R. Rojas et al. Plant Dis. 77:340, 1993.
First Report of Phytophthora cinnamomi Root Rot, Stem, and Leaf Blight on Ivy
Authors: Thinggaard K. , Toppe B. 
Published: May 2007

Phytophthora cinnamomi was isolated from varieties of Hedera helix pot plants in 1989 in two Danish greenhouse nurseries. The symptoms were brown, rotten roots and stems, and brown areas developing from the base of the leaves. The fungus was isolated directly from roots, stems, leaves, and soil, and by baiting the nutrient solutions of the watering systems with needles of Cedrus deodara. The fungus was isolated on Phytophthora selective agar medium containing hymexazol and identified with the keys of Kröber (1) and Stamps et al. (2). The fungus was characterized by coralloid hyphal swellings, chlamydospores, lack of oogonia in single culture, and production of numerous, ovoid sporangia with a nonpapillate, wide pore. The sporangia produced many zoospores after 2 days flooding with autoclaved pond water on V8 juice agar, followed by internal proliferation. The fungus was also isolated in Norway in 1993 from ivy pot plants. The fungus was widespread in Danish and Norwegian pot plant nurseries in 1997 and caused losses in most varieties, especially at temperatures above 23°C. Effective fungicides are not available for use in Denmark and the disease is easily spread with cuttings, and through the watering system with recirculation of the nutrient solution. A Danish isolate of P. cinnamomi originating from roots of H. helix was used in a pathogenicity test. Five-week-old cuttings were inoculated by adding zoospores (5 per ml) to the recirculating nutrient solution. Control plants were on a separate bench with nutrient solution without the fungus. After 1 week, symptoms of root rot were observed, and 2 weeks after inoculation, 75% of plants expressed severe symptoms on roots, stems, and leaves. P. cinnamomi was reisolated from roots, stems, and leaves of diseased plants, but was not isolated from the control plants. The reisolate was morphologically identical to the original isolate. This is the first report of P. cinnamomi from ivy in Europe. References: (1) H. Kröber. Mitt. Biol. Bundesanst. Land Forstwirtsch. Berlin-Dahlem 225:73, 1985. (2) D. J. Stamps et al. 1990. Mycol. Pap. No. 162. CAB Int. Mycol. Inst., Kew, England.
The Appearance of Metalaxyl-Resistant Isolates of Phytophthora infestans in Delaware
Authors: Sedegui M. , Carroll R. B. , Morehart A. L. , Mulroony R. P. , Whalen J. M. 
Published: May 2007

Prior to 1995, late blight of potatoes (Solanum tuberosum L.) caused by Phytophthora infestans (Mont.) de Bary had not been reported from Delaware for decades. In that year, the fungus was isolated from potato foliage collected from fields in the Dover area that sustained severe foliage loss due to the disease. To establish pathogenicity, potato and tomato plants grown in the greenhouse were inoculated with the isolates obtained and Koch's postulates were completed. Analyses to determine mating type, genotype at two allozyme loci (2), Gpi and Pep, and sensitivity to metalaxyl were also completed. Measurements were made every 5 days and EC50 values were calculated for radial mycelial growth on metalaxyl-amended agar, for leaflets inoculated with P. infestans floated in metalaxyl solutions, and for inoculated potato tuber disks deposited on filter paper saturated with metalaxyl (1). Isolates were pathogenic to potatoes and tomatoes, were A2 mating type with Gpi 100/111/122 and Pep 100/100 (same as US-8), and displayed resistance to metalaxyl up to 140 mg/l. References: (1) K. L. Deahl et al. Am. Potato J. 70:779, 1993. (2) S. B. Goodwin et al. Plant Dis. 79:1181, 1995.
A New Race of Fusarium oxysporum f. sp. melonis Causing Fusarium Wilt of Muskmelon in the Central Valley of California
Authors: Gwynne B. J. , Gordon T. R. , Davis R. M. 
Published: May 2007

In 1996, cantaloupe (Cucumis melo L. cv. Durango) vines in two fields exhibited wilt, vascular discoloration, and necrotic streaks on the stems. Fusarium oxysporum Schlechtend.:Fr. was isolated from the stems of vines from both fields. One isolate from each field was compared with known isolates of F. oxysporum f. sp. melonis (Leach & Currence) W.C. Snyder & H.N. Hansen races 1 and 2 in a differential host range experiment in the greenhouse. Three-week-old seedlings were root-dip inoculated with monoconidial isolates at a concentration of 5 × 105 spores per ml. Control plants were dipped in water. In two experiments, the test isolates killed the susceptible varieties Top Mark and Magnum .45 and the race 2 resistant varieties Durango, Gold Mine, and Perlita FR. Seedlings of variety Charentais with the Fom2 gene conferring resistance to race 1 were resistant to both test isolates. It was determined that both of these isolates are associated with vegetative compatibility group (VCG) 0134 (1). This is the first report of race 1 and VCG 0134 of F. oxysporum f. sp. melonis causing Fusarium wilt of muskmelon in the Central Valley of California, and the first reported occurrence of race 1 in California since 1973 (2). Cantaloupe varieties currently grown in California are susceptible to race 1 of F. oxysporum f. sp. melonis References: (1) D. J. Jacobson and T. R. Gordon. Phytopathology 78:668, 1988. (2) J. V. Leary and W. D. Wilbur. Phytopathology 66:15, 1976.
Leaf Curl Disease of Carica papaya from India May Be Caused by a Bipartite Geminivirus
Authors: Saxena Sangeeta , Hallan Vipin , Singh B. P. , Sane P. V. 
Published: May 2007

Papaya has considerable economic importance to agriculture in India. Papaya leaf curl disease was first reported in 1939 by Thomas and Krishnaswamy (3). This disease is of moderate incidence and widely distributed in India. Recent observations of papaya fields in India indicated that there has been a continued increase in the incidence of papaya leaf curl disease (as shown by symptoms), resulting in severe economic losses. The disease is characterized by downward curling and cupping of leaves followed by vein clearing and thickening. Enations develop in the form of frills on green veins. The affected leaves become leathery and brittle and the petioles become twisted in a zig-zag manner. Diseased plants may bear a few small fruits, which are distorted in shape and tend to fall prematurely. The disease could be transmitted by the whitefly Bemisia tabaci Genn. Therefore, possible involvement of a geminivirus was suspected. Three different cloned geminiviral DNAs, Indian tomato leaf curl virus (ITLCV) (2), tomato yellow leaf curl virus from Sardinia (TYLCV Sar), and tomato golden mosaic virus (TGMV), were used as probes (with radioactive labeling) to detect the presence of geminiviral DNA from infected papaya tissue in both slot-blot and Southern blot hybridization studies with high stringency washes. These DNA probes gave strong signals with DNA isolated from infected papaya tissue whereas they did not give any signals with DNA from healthy tissue. Further, successful polymerase chain reaction (PCR)-based amplification of fragments from both DNA-A and DNA-B components with geminivirus degenerate primers (1) was accomplished only from the DNA of infected papaya plants. The PCR-amplified DNA fragments gave positive signals in Southern blot hybridization with the three geminiviral DNA probes. These results suggest that the causal agent of papaya leaf curl disease is a bipartite geminivirus that may be provisionally called papaya leaf curl virus (PLCV). References: (1) M. R. Rojas et al. Plant Dis. 77:340, 1993. (2) K. M. Srivastava et al. J. Virol. Methods 51:297, 1995. (3) K. M. Thomas and C. S. Krishnaswamy. Curr. Sci. 8:316, 1939.
First Report of Rhizoctonia solani AG-7 on Potato in Mexico
Authors: Carling D. E. , Brainard K. A. , Virgen-Calleros G. , Olalde-Portugal V. 
Published: May 2007

Among isolates of Rhizoctonia solani Kühn collected as sclerotia from potato (Solanum tuberosum L.) tubers harvested from the Toluca Valley in 1995 was one isolate (MexND) of anastomosis group 7 (AG-7). Virulence of this and other isolates of R. solani representing AG-3 (four isolates) or AG-7 (four isolates), was determined on developing potato plants (cv. Russet Burbank) in growth chamber studies at 10 and 21°C by methods used previously (1). A control treatment was inoculated with sterile disks of potato dextrose agar (PDA). Seed tubers were placed on a layer of pasturized sand-soil mix near the bottom of 6- × 25-cm black plastic tubes, then covered with 2 to 3 cm of the sand-soil mix. Seed tubers used in virulence tests carried no R. solani as they had been surface disinfested by immersing for 2 min in a 1.85% solution of formaldehyde. Inoculum, in the form of one 7-mm agar disk cut from the growing edge of appropriate colonies growing on PDA, was placed 2 to 3 cm above the seed and covered with 7 to 10 cm of sand-soil mix (1). Each treatment had five replications. Plants were harvested after control plants had emerged, 29 days at 21°C and 36 days at 10°C, and damage to roots and shoots was assessed according to Carling and Leiner (1). All four isolates of AG-3, one from the U.S. and three from Mexico, caused major damage to roots and shoots at both temperatures. The two isolates of AG-7 from the U.S. caused superficial discoloration to shoots at both temperatures but the two isolates of AG-7 from Japan caused no damage to shoots. None of the four isolates of AG-7 damaged roots at either temperature. MexND caused no damage to roots or shoots at 21°C but produced lesions (< 1 mm in diameter) on roots and shoots at 10°C. Thus, MexND caused less damage to potato than AG-3, more damage than other isolates of AG-7, and appears more aggressive at lower temperatures. This is the first reported occurrence of R. solani AG-7 in Mexico and its first reported recovery from a potato tuber-borne sclerotium. Reference: (1) D. E. Carling and R. H. Leiner. Phytopathology 80:930, 1990.
First Report of Anthracnose of Lentil Incited by Colletotrichum truncatum in Bulgaria
Authors: Kaiser W. J. , Mihov M. , Muehlbauer F. J. , Hannan R. M. 
Published: May 2007

In June 1992 and 1995, anthracnose of lentil (Lens culinaris Medik.) incited by Colletotrichum truncatum (Schwein.) Andrus & W. D. Moore was widespread in field trials at the Institute for Wheat and Sunflower ‘Dobroudja’ near General Toshevo in northeastern Bulgaria. Lesions on the leaves, stems, and pods were usually white to grayish on younger plants, often turning brown as plants matured. Severe infection usually resulted in dieback and/or death of plants. Acervuli containing spores and dark setae were observed within lesions, and conidia from the acervuli produced pure cultures of C. truncatum. Conidia were hyaline, onecelled, falcate to nearly straight with a prominent clear area in the center of highly granular cytoplasm, and measured 17.6 to 19.8 × 4.4 μm. C. truncatum was seed-borne in naturally infected lentil cv. Tadjikskaya 95 at low frequencies (<2%). Koch's postulates were fulfilled by inoculating the foliage of lentil cvs. Brewer and Pardina and reisolating the fungus from stem and petiole lesions. In pathogenicity tests, three isolates of C. truncatum from the foliage and seeds of lentil caused severe symptoms on inoculated lentil cvs. Brewer and Pardina, similar to those observed on diseased lentils in Bulgaria. The fungus also caused moderate symptoms on inoculated faba bean (Vicia faba L.) and pea (Pisum sativum L.), and light symptoms on inoculated chickpea (Cicer arietinum L.). In 1995, 258 USDA Plant Introduction (PI) accessions from the USDA lentil core collection were screened in replicated trials in northeastern Bulgaria and disease symptoms were observed in >90% of the lines. Anthracnose severity ranged from light to severe. A few accessions appeared to have acceptable levels of resistance to the disease. These included accessions from Iran (PI 431714 and 431717) and Spain (PI 533693). Also that year, C. truncatum was isolated from stem lesions of naturally infected bitter vetch (Vicia ervilia (L.) Willd.) at the Institute for Wheat and Sunflower ‘Dobroudja’. The disease in Bulgaria appears to be identical to one causing anthracnose of lentil in Canada (1) and the United States (2). This is the first report of C. truncatum causing anthracnose of lentil in Bulgaria. References: (1) R. A. A. Morrall. Plant Dis. 72:994, 1988. (2) J. R. Venette et al. Plant Dis. 78:1216, 1994.
A Tuber Rot of Cyperus esculentus Caused by Rosellinia necatrix
Authors: García-Jiménez J. , Busto J. , Vicent A. , Sales R. , Armengol J. 
Published: May 2007

Tiger nut (Cyperus esculentus L.) is cultivated in Spain for the production of tiger nut milk. Over the past 5 years, important economic losses resulting from a new tuber rot have been observed near Valencia in eastern Spain. Affected tubers were covered by a white mycelium that turned black as the disease advanced, leading to a general rotting of tubers. Aboveground plant parts showed some early decay and under high-moisture environmental conditions the white mycelium was present on the soil surface. This mycelium showed pyriform swellings characteristic of Rosellinia necatrix Prill., and coremia were occasionally observed on external surfaces of tubers after incubation in a moist chamber for 1 to 2 months. Coremia produced small ellipsoid or obovoid single-celled conidia 3.7 to 5.0 × 2.0 to 2.2 μm. The teleomorph has not been observed. Pathogenicity tests were conducted with inoculum produced on wheat (Triticum aestivum L.) seeds that were soaked for 12 h in flasks filled with distilled water. Each flask contained 300 ml of seeds that were subsequently autoclaved after excess water was drained. Two fungal disks of a 2-week-old culture of R. necatrix grown on potato dextrose agar were placed aseptically in each flask. The flasks were incubated at 25°C for 4 weeks, and shaken once a week to avoid clustering of inoculum. Two plastic pots (35 cm in diameter) per isolate were filled with a sterilized mixture of equal portions (vol/vol) of soil, sand, and peat moss, and inoculum was added at a concentration of 30 g of infected wheat seeds per 1,200 g of substrate (1). Healthy tubers were surface disinfested in 1.5% (vol/vol) sodium hypochlorite for 1 min, washed twice in sterile water, sown, and subsequently thinned to one per pot after emergence. Plants were grown under field conditions. Six months after inoculation, symptomatic tubers appeared similar to those originally observed in the field. The fungus was reisolated from affected tubers, confirming Koch's postulates. Pathogenicity tests were also conducted on avocado (cv. Reed) and almond (cv. Garriges) seedlings, and apple rootstock (MM-106) as very susceptible host plants for R. necatrix (1). Inoculated plants showed symptoms of wilting and death 4 weeks after inoculation. The fungus was reisolated from affected plants. This is the first report of C. esculentus as a host of R. necatrix. Reference: (1) A. Sztejnberg and Z. Madar. Plant Dis. 64: 662, 1980.
First Report of Pythium polymastum on Broccoli and Cauliflower in California
Authors: Aegerter B. J. , Davis R. M. 
Published: May 2007

Damping-off of broccoli (Brassica oleracea var. italica) and cauliflower (B. oleracea var. botrytis) seedlings occurred in several greenhouses in Fresno, CA, in 1997. Symptoms included wilting and root and stem rot. Pythium polymastum was consistently isolated from symptomatic tissues placed on corn meal agar amended with 10 ppm pimaricin, 250 ppm ampicillin, 10 ppm rifampicin, and 25 ppm pentachloronitro-benzene. On grass leaves in water, the fungus produced numerous aplerotic oospores in oogonia 43 to 50 μm in diameter (average 46 μm) with spines about 7 μm long. Spherical sporangia were only rarely observed. In the greenhouse, 4-week-old broccoli and cauliflower seedlings were transplanted into potting mix amended with a colonized vermiculite/rye/V8 juice medium to produce approximately 2,500 CFUs per gram of potting medium. Control plants were transplanted into noninfested potting mix. There were six replicate pots per treatment and three plants per pot. After 12 days, the potting mix was gently washed from the roots and the seedlings were dried and weighed. Symptoms on inoculated plants included wilting, severe root rot, black streaks on the lower stems, and death. The fungus was recovered from symptomatic tissues. There were no symptoms on the control plants. Infection by P. polymastum reduced dry weights of surviving broccoli and cauliflower seedlings by 82 and 58%, respectively. Similar results were obtained in a second experiment. This fungus was previously characterized as a pathogen of both cultivated and wild crucifers in Canada (1). This is the first report of P. polymastum in California. Reference: (1) T. C. Vanterpool. Can. J. Bot. 52:1205, 1974.