bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of Infection of Honeydew with Acidovorax avenae subsp. citrulli
Authors: Isakeit T. , Black M. C. , Barnes L. W. , Jones J. B. 
Published: May 2007

Honeydew fruits (Cucumis melo var. inodorus Jacq. ‘Morning Ice,’ ‘Honeybrew,’ and ‘Green Flesh’) with circular, 3- to 10-mm-diameter lesions that did not extend into the flesh of the fruit were collected from a field in Frio County, TX, in October 1996. Lesions were either water-soaked or had a scabby center with a water-soaked edge. Non-fluorescent, gram-negative bacteria were consistently isolated from lesions. Eleven representative bacterial strains had 0.835 to 0.950 similarity to Acidovorax avenae subsp. citrulli, using Biolog GN Microplates and the MicroLog data base release 3.50 (Biolog, Hayward, CA). Strains were tested for pathogenicity on watermelon (C. lanatus (Thunb.) Matsum. & Nakai ‘Royal Sweet’) and honeydew seedlings (cv. Morning Ice) by daubing suspensions (approximately 108 CFU/ml) of bacteria onto cotyledons of 1-week-old transplants. Water soaking, followed by necrosis, occurred after 3 to 5 days. A. avenae subsp. citrulli, the causal agent of bacterial fruit blotch of watermelon, was reisolated from lesions. Detached fruit of honeydew (various cultivars) and watermelon (cv. Emperor) were surface disinfested with 70% ethanol, injected sub-epidermally with bacterial suspensions in blemish-free areas, and incubated at 24°C. Water-soaked lesions developed on fruit 10 to 14 days later and the bacteria were reisolated from inoculated fruit. Fruit inoculated with sterile water did not develop symptoms. Female flowers of honeydew plants (cv. Honeybrew) were inoculated at the time of pollination with a suspension of bacteria daubed on the fruit surface. Pollinated fruits were sealed in a moist chamber for 48 h. Circular, water-soaked spots developed 10 to 14 days later. A. avenae subsp. citrulli was reisolated from these lesions. The affected 44-ha field utilized center pivot irrigation and the incidence of diseased fruit exceeded 50%. The source of the pathogen is unknown. Bacterial fruit blotch was identified in watermelon grown under overhead irrigation 0.8 km from this honeydew field 9 weeks earlier. In past years, bacterial fruit blotch has occurred in watermelon fields in Frio County (1). Honeydew from other fields in the vicinity, including one that was also sprinkler irrigated, did not show these symptoms. This is the first report of A. avenae subsp. citrulli causing a disease of honeydew fruit. Reference: M. C. Black et al. Plant Dis. 78:831, 1994.
First Report of Leaf Scald Disease and Ratoon Stunting Disease of Sugarcane in French Guyana
Authors: Feldmann P. , Daugrois J. , Davis M. J. , Chatenet M. , Rott P. 
Published: May 2007

In December 1995, leaf scald symptoms were observed in sugarcane (Saccharum sp.) cultivar B64277 in French Guyana. Symptomatic plants occurred both in a sugarcane germplasm collection near the road between Sinnamary and Saint-Elie and in a nursery near Sinnamary. Sugarcane imported from Martinique had been used to establish the germplasm collection that in turn had been used to establish the nursery. Ten-month-old mature plants in the germplasm collection had abnormal side shoots on the lower part of the stalks and suckers (nonmillable stalks) with white scalded areas on leaves. Leaves on 1-month-old shoots in the nursery exhibited chlorosis and white, pencil-line streaks. Samples prepared from symptomatic stalks from the two locations were plated on a selective medium (1), and two isolates of Xanthomonas albilineans were recovered. Both of these isolates caused leaf scald symptoms on leaves of sugarcane cultivar B69566 inoculated by a decapitation technique, and belong to serovar 3 previously reported in the Caribbean from Guadeloupe, Martinique, and St. Kitts. The RFLP (restriction fragment length polymorphism) pattern of these two isolates was different from the 54 patterns among 218 other strains collected throughout the world (2), but similar to the pattern of a strain of serovar 3 from Martinique. This indicated that the pathogen might have been introduced with cuttings imported from Martinique. Three stalks of mature cane from varieties B5992, B64277, and R570 from the germplasm collection were tested for the presence of Clavibacter xyli subsp. xyli, causal agent of ratoon stunting disease. Immunofluorescence tests on sap (3) revealed the presence of the pathogen in the three stalks of B64277. All sugarcane plants in the nursery and the germplasm collection were destroyed by the use of glyphosate sprays in January 1996 in an attempt to arrest the spread of the two bacterial pathogens. In order to obtain healthy seed cane for future planting, a new germplasm collection of 0.6 ha and consisting of 11 cultivars was planted in January 1996 with disease-free, tissue-cultured plants provided by the CIRAD sugarcane breeding station in Guadeloupe. References: (1) M. J. Davis et al. Plant Dis. 78:78, 1994. (2) M. J. Davis et al. Phytopathology 87:316, 1997. (3) M. J. Davis and J. L. Dean. Plant Dis. 68:896, 1984.
First Report of Sorghum Ergot Caused by Sphacelia sorghi in Mexico
Authors: R. J. Aguirre , A. H. Williams , G. N. Montes , Cortinas-Escobar H. M. 
Published: May 2007

In the winter of 1996-1997 ergot was observed in sorghum (Sorghum bicolor) plants growing in several locations of Tamaulipas, Mexico, including San Fernando, Soto La Marina, Manuel, Cuahutemoc, and Altamira. The disease in sorghum plants was associated with high humidity and low temperatures during the blooming stage in February, 1997. The most obvious symptom was the exudation of honeydew from the infected flowers. Microscopic analysis of the honeydew revealed the presence of the asexual conidia of a Claviceps sp. The abundance, size, and shape of conidia were characteristic of Sphacelia sorghi (1). Honeydew was also observed in plants of Sorghum halepense, forage sorghum and volunteer plants of sorghum, which are also hosts. The first report of ergot in the Americas was made in 1995 in Brazil (2), where it was probably introduced via contaminated seed from Africa. The disease spread rapidly from Brazil to Argentina, Bolivia, Colombia, Paraguay, and Venezuela. The pathogen was probably dispersed and introduced to Mexico by contaminated seed, wind, or insects from South America. The disease represents a serious threat to the 800,000 ha of sorghum grown in Tamaulipas. Due to its confirmed extraordinary capacity to spread rapidly, ergot could affect sorghum growing in regions adjacent to Tamauli-pas, including Nuevo Leon in Mexico, and Texas in the U.S. References: (1) D. E. Frederickson et al. Mycol. Res. 95:1101, 1991. (2) E. M. Reis et al. Plant Dis. 80:463, 1996.
First Report of Web Blotch of Peanut Caused by Phoma arachidicola in the Dry Zone of Sri Lanka
Authors: Mikunthan G. 
Published: May 2007

Foliar symptoms of web blotch were observed on some peanut cultivars (Arachis hypogaea L.) grown in the Kilinochchi district in the dry zone of Sri Lanka during October 1993 to January 1994, following heavy rains (mean relative humidity 79 to 85%, mean temperature 25 to 27°C). Severe symptoms appeared on peanut cultivars ICGS 11 and ICGS 121. Cultivar ICGS 11 belongs to the Spanish group (A. hypogaea subsp. fastigiata var. vulgaris) and ICGS 121 belongs to bunch type (A. hypogaea subsp. hypogaea var. hypogaea). Initial symptoms of small, irregular, brown to reddish brown lesions along the midrib of both young and old leaves were observed. Large, nearly circular tan or dark brown blotches appeared on the adaxial surface of the leaves. Older lesions became dried and cracked. Lesions on the abaxial surface were pale brown, and less pronounced. These observations correlate closely with those made by Taber (2). Severe defoliation was observed in the infected fields of Spanish cultivars. Phoma arachidicola Marasus, G. D. Pauer, & Boerema was consistently isolated from symptomatic tissue. Colonies on potato dextrose agar were at first creamy white, and flattened with little aerial growth. Colonies eventually turned dark brown with a wide appressed margin. All isolates produced pale to dark brown and globose pycnidia. Dark-colored, globose, beaked pseudothecia were also observed in cultures, as reported by Subrahmanyam et al. (1). Dark-colored, round, single-celled pycnidiospores measuring 4 to 9 × 2.5 to 4 µm were observed in culture. The fungus was inoculated onto the leaves of 10 healthy plants of each cultivar and another 10 plants were maintained as uninoculated controls. All plants were covered with polypropylene bags to increase the humidity. Plants inoculated with the fungus produced symptoms 7 to 9 days after inoculation similar to those observed in the field. None of the control plants showed any disease symptoms. The fungus was reisolated from the diseased leaf tissue. Microscopic examination confirmed the identity of the fungus and satisfied Koch's postulates. All cultivars were then grown under irrigation during February to May 1994 (mean relative humidity 60 to 70% and mean temperature 32 to 35°C). No disease symptoms were observed, indicating that the proliferation of P. arachidicola on Spanish cultivars was influenced when the crop establishment period coincided with low air temperature (25 to 27°C) and high relative humidity (79 to 85%). This is the first report of web blotch in Sri Lanka and its occurrence was confined to the dry zone areas of the country. References: (1) P. Subrahmanyam et al. 1994. Web blotch disease of groundnut. Inform. Bull. No. 43, ICRISAT; and Peanut Collaborat. Res. Support Prog. (2) R. A. Taber. Web blotch. Pages 9–10 in: Compendium of Peanut Diseases. D. M. Porter, D. H. Smith, and R. Rodrigues-Kabana, eds. American Phytopathological Society, St. Paul, MN, 1984.
Incidence of Fusarium spp. in Asparagus Spears
Authors: Guerrero Cosme , Nigh E. L. , Stanghellini M. E. , Elmer W. 
Published: May 2007

Fusarium proliferatum and F. oxysporum have been identified as causal agents of asparagus decline in the field and have been associated with reduction in spear quality (1,2). Our objective was to determine the origin and incidence of spear infection by these fungi during the cropping years 1994 to 1997. From 15 to 40 asparagus samples were randomly selected from the field, packing houses, and retail markets and assayed for Fusarium spp. Collections were made in California, Connecticut, Peru, Mexico, and Australia. The number of samples varied between sampling sites and for the time of harvest season. One Mexican collection site was sampled at the beginning, mid-point, and end of the harvest season to evaluate influence of decreasing carbohydrate levels and increasing temperatures on infection and growth of the fungi. Isolations included sections (5 to 6 cm) from the basal and terminal portions of the spear to evaluate postharvest growth in the spear. Fusarium spp. were recovered from spear samples that included all geographical sampling locations (mean 45%, range 20 to 90%). F. proliferatum was the dominant species isolated consistently from the desert areas regardless of harvest period. The frequency of F. oxysporum isolation ranged from 2 to 32% with no correlation to time or location of sampling. Basal sections were more frequently infected (94%) than terminal portions of the spear (less than 6%). No major differences in the percentage of infected spears were found in collection sites regardless of country sampled. There were differences in the incidence of infection between harvest sample dates. Spears sampled late in the harvest period were 57% more infected than spears of early or mid-season collections. Samples from the same fields, regardless of whether collected directly from the field, from packing sheds, or from the retail market, had higher infection rates later in the harvest season compared with earlier harvests. This may be attributable to warmer temperatures, changes in levels of carbohydrates, or other physiological factors. Spears harvested from the field that were infected with both Fusarium spp. had a greater incidence of infection than spears recovered from packing houses or from retail sources. This supports the theory that the source of spear infection is diseased crowns and not postharvest sources. Isolates from the spears of both Fusarium spp. were found to be pathogenic when challenged to asparagus seedlings. References: (1) R. G. Grogan and K. A. Kimble. Phytopathology 49:122, 1959. (2) W. Schreuder et al. Plant Dis. 79:177, 1995.
First Report of Sclerotinia sclerotiorum on Coneflower
Authors: Chang K. F. , Howard R. J. , Gaudiel R. G. , Hwang S. F. 
Published: May 2007

Purple coneflower (Echinacea purpurea (L.) Moench; Asteraceae), a perennial herb originating from North America, is used as a garden ornamental and is grown commercially for use in medicinal preparations as an immunostimulant. In October 1996, a previously undescribed stem rot disease was observed in a research plot of 6-month-old echinacea plants at Brooks. Seedlings had been raised in small rockwool cubes (2 × 2 × 5 cm3) in a greenhouse, then transplanted into the field in early June. By late August, dead and dying plants were observed throughout the stand. They had dark brown to black stem lesions above and at the soil level and dead leaves with bleached petiole lesions that extended ca. 15 cm above the axil. Diseased stems and petioles often disintegrated, leaving only fibrous tissues intact. Roots were rotted and black. Superficial white mycelium developed over the basal part of affected stems. Black, oblong to irregular-shaped sclerotia, 5.1 to 17.6 mm in size, formed externally on the crown areas after plant death. Sclerotinia sclerotiorum (Lib.) de Bary (1) was isolated from the diseased plants. Five isolates were selected to fulfill Koch's postulates with 3-month-old echinacea seedlings grown in 12-cm pots of soilless mix. Sclerotia from wilted, field-grown echinacea plants were transferred onto potato dextrose agar medium for 2 days at 20°C. Agar disks were cut with a 1-cm cork borer and two plugs containing sclerotial and mycelial tissues were inserted into the soilless mix 0.5 cm deep and 0.5 cm from the opposite sides of stems of test plants. Inoculated plants were enclosed in transparent plastic bags for 5 days and incubated in a growth chamber at 15/18°C (night/day) with a 12-h photoperiod. One to four lower leaves per plant wilted within 1 week after inoculation and aerial mycelia appeared on the petioles. Infected leaves quickly withered, dried, and dropped off the plant after the bags were removed. Plants often died 3 weeks after inoculation and S. sclerotiorum was reisolated from infected crown tissues. This disease was also found on 3-year-old plants of E. pallida (Nutt.) Nutt. var. angustifolia (DC.) Cronq. in Vernon, British Columbia, Canada, in May 1997. This is the first report of sclerotinia stem rot on Echinacea spp., a disease that could have a significant impact on the longevity and productivity of this crop in the field and greenhouse. Reference: (1) L. H. Purdy. Phytopathology 69:875, 1979.
First Report of Powdery Mildew, Caused by Erysiphe cruciferarum, on Broccoli Raab in California
Authors: Koike S. T. , Saenz G. S. 
Published: May 2007

Broccoli raab (Brassica rapa subsp. rapa), also known as rappini, is a leafy vegetable that is widely grown in Europe and has in recent years become an important crop in coastal California. During summer months in the Salinas Valley (Monterey County) in California, powdery mildew was observed on commercial field and greenhouse-grown plants. White ectophytic mycelial and conidial growth was present on leaves, causing chlorosis, and also developed on stems. Mycelia were amphigenous, in patches, often spreading to become effused. Appressoria were lobed and conidiophores were straight. Foot cells were cylindrical, measured 18 to 26 × 7 to 10 μm, and were followed by one to two cells of variable length. Conidia were produced singly, were cylindrical, and measured 35 to 50 × 12 to 21 μm with a length-to-width ratio greater than 2. No fibrosin bodies were observed in the conidia, and conidia germinated at the ends. Cleistothecia were not observed. The fungus was identified as Erysiphe cruciferarum Opiz ex Junell (1). Pathogenicity was demonstrated by gently pressing infected leaves having abundant sporulation onto leaves of potted broccoli raab (cv. Spring Raab), incubating the plants in a moist chamber for 48 h, and then maintaining plants in a greenhouse. After 10 to 13 days, powdery mildew colonies developed on the test plants. Uninoculated control plants did not develop powdery mildew. With the same inoculation procedure, potted broccoli (Brassica oleracea subsp. botrytis cv. Greenbelt) also became infected by the broccoli raab isolates. This is the first report characterizing this pathogen on broccoli raab in the state. Disease incidence and severity in field-planted crops were low, but greenhouse-grown plants became severely infected. Reference: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987.
First Report of Banana Bunchy Top Virus in Malawi
Authors: Kenyon Lawrence , Brown Margaret , Khonje Patrick 
Published: May 2007

Banana plants of the Cavendish subgroup (Musa AAA, locally known as “Kabuthu”) with classical banana bunchy top virus (BBTV) symptoms were observed to be widespread in Thiwi Valley, Salima Agricultural Development Division, Malawi. The symptoms included marginal yellowing of the younger leaves, dark green, dot-dash streaks along the veins, petioles, and midribs, and shortened internodes. The aphid vector of this virus, Pentalonia nigronervosa, was abundant on bananas in this area (H. Thindwa, personal communication). Young leaf and midrib samples from apparently healthy plants and plants with symptoms were transported to the United Kingdom for testing. In a triple antibody sandwich enzyme-linked immunosorbent assay (ELISA) with poly- and monoclonal antibodies specific for BBTV (1), the samples from symptomatic plants gave positive reactions (OD infected ≥ OD healthy + 3SE healthy). Polymerase chain reaction (PCR) amplification tests were performed for confirmation with oligonucleotide primers BBT1 and BBT2, which are homologous to conserved regions in BBTV DNA component 1. All ELISA-positive samples produced a PCR amplification product of about 349 bp, whereas the healthy control samples did not. The sizes of the DNA fragments produced following restriction enzyme digest of the PCR product suggest that the Malawi virus falls within the South Pacific group of BBTV isolates (2). The presence of both the virus and its vector has the potential for causing great economic damage to this important banana-growing region, and recommendations have been made to eradicate all plants with symptoms. References: (1) R. G. Dietzgen and J. E. Thomas. Australas. Plant Pathol. 20:161, 1991. (2) M. Karan et al. J. Gen. Virol. 75:3541, 1994.
Yellow Net of Triumffeta Is Caused by a Geminivirus: A First Report
Authors: Hallan Vipin , Saxena Sangeeta , Singh B. P. 
Published: May 2007

Triumffeta rhomboidiaceae Jacq. (Tiliaceae family) is an annual rainy season weed that is commonly found throughout India. For the last 3 years, during the rainy season, several plants of T. rhomboidiaceae in and around the gardens of the National Botanical Research Institute have been found with vein yellowing symptoms. The initial symptoms were vein clearing but in later stages the veins became yellow and thickened. In severe cases, the chlorosis extends into interveinal areas, resulting in complete yellowing of the leaves. In a few cases, green leafy or thorny enations could be seen on the dorsal side of the leaf. The disease was investigated to identify the causal agent. Vector transmission studies showed that the causal agent is transmitted by the whitefly, Bemisia tabaci, from infected to healthy seedlings of T. rhomdoidiaceae. Since whitefly transmission of the disease is consistent with a geminivirus as the causal agent, the role of such a virus was investigated. DNA isolated from Triumffeta plants (both from the infected plants in the field as well as from those inoculated experimentally in the greenhouse) showing above mentioned symptoms was amplified with two sets of degenerate primers, PAL1v1978/PAR1c496 (set 1) and PAL1v1978/PCRc1 (set 2), that have been shown to be specific for DNA-A of whitefly transmitted geminiviruses (WTGs), in polymerase chain reaction (1). We could amplify DNA-A fragments of approximately 1.2 kb from set 1 and 0.7 kb from set 2, as expected (1). DNA isolated from healthy seedlings gave no amplification of such fragments. Identification of the amplified DNA fragments (from infected samples) to be of geminiviral in nature was confirmed by Southern blot hybridization carried out under high stringency conditions. DNA-A of Indian tomato leaf curl virus (2) was used as a general probe for WTGs for the above hybridization experiment. Therefore, Triumffeta yellow net disease is caused by a geminivirus. A review of literature revealed that there is no record of a viral disease affecting this weed and, therefore, this is the first report of a viral disease affecting this plant. References: (1) M. R. Rojas et al. Plant Dis. 77:340, 1993. (2) K. M. Srivastava et al. J. Virol. Methods 51:297, 1995.
First Report of Powdery Mildew Caused by Oidium araliacearum on Ivy in California
Authors: Saenz G. S. , Koike S. T. 
Published: May 2007

Powdery mildew was observed on English ivy (Hedera helix L.) in Berkeley, CA, in the spring of 1997. Fungal growth was ectophytic and amphigenous on leaves and petioles and caused slight reddening and buckling of leaves. The mycelium was white, effuse to dense, and had hyphal diameters of 3.5 to 6.9 μm. Appressoria were nipple-shaped to lobed, and sometimes were opposite. The foot cells of the conidiophores were cylindric, sometimes slightly flexuous, and were 18.5 to 30.0 × 6.9 to 9.2 μm in diameter. The foot cells were followed by 1 or 2 cells. When only one cell followed the foot cell, this cell was longer and slightly wider than the foot cell and measured 20.8 to 46.2 × 6.9 to 9.2 μm. When two cells followed the foot cell, these cells were of similar length to the foot cell, with the second cell usually shorter. Conidia were formed singly, were cylindric to slightly doliiform, and measured 32.0 to 44.0 × 11.5 to 19.0 μm. Fibrosin bodies were not observed. Conidia germinated at the ends and germ tubes terminated in lobed appressoria, placing this fungus in the Polygoni-type germination category (2). Cleistothecia were not observed. Based on these characters, the fungus was identified as Oidium araliacearum U. Braun & E. Oehrens B. A specimen was deposited with the University of California at Berkeley herbarium (accession number UC1713247). Pathogenicity was confirmed by gently pressing infected leaves onto leaves of various stages of maturity on ivy vines (3 to 4 vines per plant; 4 plants). Inoculated plants were kept in a moist chamber for 48 h, and then maintained in a greenhouse. Powdery mildew developed on inoculated plants, primarily on leaves of intermediate maturity, after 14 days, while uninoculated plants did not develop disease. Phyllactinia guttata is the only other powdery mildew recorded on English ivy (2). O. araliacearum differs from P. guttata in conidial shape (cylindric vs clavate), germination habit (end vs side of conidia), and asexual genus (Oidium vs Ovulariopsis) (2). Previous to this report, O. araliacearum was described only on Pseudopanax valdiviensis, another Araliaceae plant, in Chile (1). This is the first report of a powdery mildew disease of ivy in California, and the first report of Hedera helix as a host of O. araliacearum. References: (1) U. Braun. Mycotaxon 25:259, 1986. (2) U. Braun. Nova Hedwigia 89:1, 1987.