bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of Colletotrichum gloeosporioides on Russian-thistle
Authors: Schwarczinger I. , Vajna L. , Bruckart W. L. 
Published: May 2007

A pathogen identified as Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. was isolated from foliar and stem lesions on Russian-thistle (Salsola tragus Torner ex L.) collected in Bugac, Hungary, in 1996. Symptoms on leaves and stems began as discrete, sunken, 2- to 10-mm-diameter chlorotic spots, followed by formation of circular buff-colored lesions that eventually coalesced, desiccated, and caused plant tissue death above the lesions. Lesions that occurred near ground level usually killed the plant. Salmon-colored spore masses developed in setose acervuli in the center of the necrotic lesions. Conidia were hyaline, one-celled, falcate to nearly straight, and measured 15 to 25 × 5 to 6 μm. The teleomorph stage of the pathogen (Glomerella cingulata (Stoneman) Spauld. & H. Schrenk) was not observed in the field or on inoculated plants. These morphological characteristics of the isolate were consistent with the description of C. gloeosporioides (1). Pathogenicity was proved by completing Koch's postulates in Hungary and the U.S. Inoculation with conidial suspension (106 conidia per ml) sprayed on S. tragus plants in the greenhouse at the three- to four-leaf stage caused severe necrosis and wilting within 6 days and plant death in 2 weeks. Symptoms did not appear on control plants inoculated with sterile, distilled water. Inoculation test was repeated on 6-week-old plants and at the stage of flowering. All treated plants were killed at both stages within 4 weeks. Because of high virulence and host specificity of this isolate of C. gloeosporioides in preliminary pathogenicity tests it is being evaluated for use as a mycoherbicide for Russian-thistle control in the U.S. This is the first report of C. gloeosporioides causing anthracnose on S. tragus. Reference: (1) B. C. Sutton. Pages 1–27 in: Colletotrichum Biology, Pathology and Control. J. A. Bailei and M. J. Jeger, eds. CAB Int., Wallingford, UK, 1992.
Binucleate Rhizoctonia on Tobacco in Zimbabwe
Authors: Masuka A. J. 
Published: May 2007

Rhizoctonia solani Kühn (teleomorph Thanatephorus cucumeris (A. B. Frank) Donk) anastomosis groups AG 4 and AG 3 cause, respectively, widespread stem rot and leaf spot diseases of tobacco in Zimbabwe (2). Stem rot leads to substantial field losses, necessitating routine chemical and biological control (1). A recent increase in reports on Rhizoctonia-induced damping-off in tobacco seedlings and lodging of mature field plants prompted detailed studies on the causal pathogen. Nuclear fluorescence microscopy studies of 83 isolates from diseased tobacco revealed the presence of binucleate isolates. The isolates were collected in 1981 (1 isolate), 1990 (1 isolate), 1996 (3 isolates), and 1997 (1 isolate) and caused damping-off in seedlings (2 isolates) and stem rot and lodging in field tobacco (4 isolates). We confirmed that all binucleate isolates contained only two nuclei per cell. There was variability in the number of nuclei among the multinucleate stem rot (mean 4.2, SE 0.265) and leaf spot (mean 7.5, SE 0.259) isolates. Two tested binucleate Rhizoctonia isolates were pathogenic to 7-week-old tobacco seedlings (cv. Kutsaga 35) in a greenhouse experiment, laid out as a randomized complete block design. Uninoculated healthy plants served as control. Based on a disease rating scale of 1 to 5 (1 = no disease and 5 = >50% stem damage), overall disease incidence was 88.9% 5 days after inoculation with macerated mycelium at the rate of 3.60 × 105 CFU per seedling, applied around the stem base. Over 50% of inoculated seedlings were rated in disease categories 4 and 5. Binucleate Rhizoctonia were consistently isolated from infected plants. A country-wide survey is being conducted to determine the incidence, distribution and severity of diseases caused by binucleate Rhizoctonia on tobacco in Zimbabwe. References: (1) J. S. Cole and Z. Zvenyika. Plant Pathol. 37:271, 1988. (2) S. I. Mpofu and A. M. Julian. J. Phytopathol. 140: 367, 1994.
First Report of Cephaleuros virescens in Arkansas and Its Occurrence on Cultivated Blackberry in Arkansas and Louisiana
Authors: Holcomb G. E. , Vann S. R. , Buckley J. B. 
Published: May 2007

Blackberry (Rubus sp.) cane samples (cultivar Navaho) showing disease symptoms were collected from a commercial grower in Texarkana, AR, and sent for diagnosis to the plant disease clinic in Lonoke in June, 1997. Cane symptoms consisted of stem cracking, tissue discoloration beneath the bark, and the presence of an orange, velvetlike growth that was identified as sporangiophores and sporangia of the parasitic green alga Cephaleuros virescens Kunze. Zoospores were released when sporangia were placed in water drops. The alga was isolated from infected canes on potato dextrose agar, but pathogenicity tests were not attempted because pathogenicity has never been demonstrated successfully, nor have zoospores been produced in culture. C. virescens also was found infecting cultivated blackberry at the Louisiana Calhoun Research Station, where it occurred more commonly on thornless than on thorned type cultivars. This parasitic alga occurs commonly along the U.S. Gulf Coast and has been recorded on 287 plant species and cultivars, including 80 that are subject to stem infections (1,2). The occurrence of C. virescens in Arkansas extends its known northernmost range from 32.5°N to 33.5°N in the U.S. This is the first report on the occurrence of C. virescens in Arkansas and the first report of its occurrence on cultivated, commercially grown blackberry. References: (1) G. E. Holcomb. Plant Dis. 70:1080, 1986. (2) R. B. Marlatt and S. A. Alfieri, Jr. Plant Dis. 65:520, 1981.
Occurrence of Turnip Yellow Mosaic Virus on Oriental Cruciferous Vegetables in Southern Ontario, Canada
Authors: Stobbs L. W. , Cerkauskas R. F. , Lowery T. , VanDriel L. 
Published: May 2007

Turnip yellow mosaic virus (TYMV) has been reported throughout Europe, New Zealand, and Australia. In 1994, this virus was identified in two field plantings of Bok Choi and one planting of Pak Choi (Brassica campestris Chinensis group var. communis) in Durham and Haldimand-Norfolk counties, respectively. In early October, approximately 25% of the plants were infected at each site. Both the striped flea beetle (Phyllotreta striolata (F.)) and the crucifer flea beetle (P. Cruciferae(Goeze)), reported vectors of the virus (1), were present at each site. Infected plants exhibited bright yellow to yellow-green mosaic mottling and often showed chlorotic lesions on the lower leaves. Vein clearing was also seen on several plants. Plants were often coinfected with turnip mosaic virus. Four symptomatic plants were taken from each field site for testing. Spherical virus particles (28 nm) were identified as TYMV by electron microscopy following post-antibody decoration and enzyme-linked immunosorbent assay with the TYMV Agdia test kit. Symptoms were reproduced on both Bok and Pak Choi by mechanical inoculation into healthy plants. Extended host range susceptibility tests with 14 differential hosts were consistent with those reported in the VIDE database (1). This virus, in the presence of the flea beetle vectors, may pose a threat to susceptible traditional cruciferous vegetables grown extensively in this area. Reference: (1) A. A Brunt et al., eds. Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version: 16th January 1997.
First Report of Moroccan Watermelon Mosaic Potyvirus in Zucchini in Italy
Authors: Roggero P. , Dellavalle G. , Lisa V. , Stravato V. M. 
Published: May 2007

Unusual symptoms were observed in summer 1997 in field zucchini of several cultivars grown in central Italy. Symptoms included reduction in growth, severe mosaic, blistering and deformation of leaves, and malformation on fruits. Plants gave negative results in enzyme-linked immunosorbent assay (ELISA) for cucumber mosaic cucumovirus, squash mosaic comovirus, papaya ringspot, zucchini yellow fleck, zucchini yellow mosaic, and watermelon mosaic 2 potyviruses. Positive reactions were obtained in ELISA with a monoclonal antibody that reacts with many potyviruses (from J. Vetten, Braunschweig) and with polyclonal antibodies (Sanofi, France) to Moroccan watermelon mosaic potyvirus (MWMV). Field symptoms were reproduced in zucchini cvs. Genovese and Striato d'Italia by mechanical inoculation of samples from symptomatic field plants. Chenopodium amaranticolor, C. quinoa, and Gomphrena globosa gave local lesions, while Citrullus lanatus cv. Crimson Sweet, Cucumis melo cv. Top Mark, C. metuliferus, C. sativus cvs. Marketer, MM76, and Sweet Slice, and Cucurbita maxima reacted with systemic mosaic. C. melo cv. Doublon formed necrotic local lesions followed by systemic necrosis. No infection occurred in Nicotiana benthamiana, N. clevelandii, N. glutinosa, Phaseolus vulgaris cv. Black Turtle, Pisum sativum cv. Alaska, tobacco White Burley, and Vigna unguiculata. These data are in agreement with the known host range of MWMV. MWMV is a tentative species in the genus potyvirus, widely present in Africa and occasionally found in Spain (1,2). Further spread of this virus in the Mediterranean area will create new problems for commercial cucurbit production and breeding, and for diagnosis. References: (1) E. Kabelka and R. Grumet. Euphytica 95:237, 1997. (2) N. M. McKern et al. Arch. Virol. 131:467, 1993.
First Occurrence of Downy Mildew of Statice, Caused by Peronospora statices, in California and the Rest of the United States
Authors: Koike S. T. , Nolan P. A. , Tjosvold S. A. , Robb K. L. 
Published: May 2007

In California, hybrid statice (Misty series; Limonium bellidifolium × Limonium latifolium) is grown as a commercial cutflower crop in fields and greenhouses. In 1997, downy mildew was observed on statice plantings in both southern (San Diego County) and central (Monterey and Santa Cruz counties) parts of coastal California. Initial symptoms consisted of light green, irregularly shaped leaf spots that, after a few days, became chlorotic. As disease progressed, chlorotic spots coalesced and turned necrotic, at times resulting in extensive death of leaf tissues. Under favorable conditions, the purple to gray sporulation of the pathogen could be seen on abaxial surfaces of leaves. Conidiophores had main trunks with dichotomous branches and measured 194 to 335 μm in length (mean = 229 μm) from the base to the first branches and 7 to 8 μm across at the widest part. Branch ends were slender with curved tips that measured 5 to 8 μm long. Conidia were ovoid to globose with very short pedicels, and measured 14 to 19 μm × 14 to 17 μm. Conidial surfaces appeared slightly roughened when viewed with a scanning electron microscope. Clearing leaf sections with 10% NaOH (1) revealed the presence of yellow-brown, globose oospores that measured 31 to 47 μm. The pathogen was identified as Peronospora statices (1). Pathogenicity was demonstrated by pressing leaves with abundant sporulation against healthy leaves of test plants (Misty White) and then placing inoculated plants in a humidity chamber. After 10 to 12 days, symptoms similar to those originally observed developed on inoculated plants; after 14 to 16 days, purple fungal growth morphologically similar to the original isolates grew on leaves. Uninoculated control plants did not develop symptoms or signs of downy mildew. This is the first report of downy mildew caused by P. statices on statice in California and the rest of the United States. The disease has also been confirmed on Blue Fantasia (L. bellidifolium × L. perezii). This disease has been reported previously in Italy, The Netherlands, and the United Kingdom (1). Reference: (1) G. S. Hall et al. Eur. J. Plant Pathol. 103:471, 1997.
First Report of Botryotinia fuckeliana on Kerguelen Cabbage on the Sub-Antarctic Marion Island
Authors: Kloppers F. J. , Smith V. R. 
Published: May 2007

Pringlea antiscorbutica R. Br. (the Kerguelen cabbage) is a monotypic species endemic to five sub-Antarctic islands. It does not occur elsewhere and is the only brassica found in the sub-Antarctic region as a whole (1). On Marion Island (46° 54′S, 37° 45′E) the distribution and abundance of the cabbage has declined alarmingly over the past 20 years and the plants increasingly are showing symptoms of microbial pathogen attack. Leaves display brown, water-soaked lesions and sometimes whole plants collapse into a black, slimy residue. Small sections of lesions were sampled, surface sterilized, and placed on water agar and potato dextrose agar (PDA) to which streptomycin (0.1 g/liter) was added. Nonsterilized sections were placed in petri dishes on moist, sterilized, filter paper. Plates were incubated at 15°C in the dark. Botryotinia fuckeliana (de Bary) Whetzel (conidial state; Botrytis cinerea Pers.:Fr) was consistently isolated. Gray to white mycelium grew rapidly on PDA and after 10 days abundant black sclerotia (2 to 16 mm long) were observed on the medium. To confirm pathogenicity, four detached leaves of P. antiscorbutica were each inoculated with a single, 5-mm-diameter PDA plug of B. fuckeliana. Four leaves with noncolonized PDA plugs were used as controls. The leaves were placed with their petioles in sterile water in a transparent incubation chamber. Chamber temperature (minimum 3.9°C, maximum 7.7°C and mean 6.4°C) and light (100 µmol s-1 m-2 photosynthetic photon flux density) approximated field conditions quite closely but relative humidity (annual mean for the island, 81%) was on average 10% higher in the chamber. First symptoms were observed after about 48 h. After 5, 7, and 8 days, brown, water-soaked lesions averaged 14 × 7, 28 × 11, and 36 × 18 mm, respectively. Control leaves showed no symptoms. Reisolations from lesions produced B. fuckeliana. Identity of the pathogen was confirmed by the South African National Collection of Fungi Biosystematics Division, Pretoria. The sub-Antarctic climate is probably conducive to the rapid spread of B. fuckeliana and to its ability to infect P. antiscorbutica. Other factors, such as the recent introduction of the diamondback cabbage moth (Plutella xylostella) to the island and grazing damage by an introduced slug species (Deroceros caruanae) probably exacerbate the threat offered by the fungus to this plant species, one of the last and perhaps the only, remaining relic of an extensive circum-Antarctic flora. Reference: (1) A. J. Dorne and R. Bligny. Polar Biol. 13:55, 1993.
Marasmiellus Leaf Disease on Maize in West Africa
Authors: Cardwell K. F. 
Published: May 2007

A leaf disease of maize previously described as borde blanco (1) or horizontal banded blight (2) was recently observed for the first time in three West African countries. The symptom was white, dry lesions that grew phasically on the edge of the leaf, resulting in horizontal bands delineated by purple to brown margins. Minute basidiocarps (1 mm high) were seen in the white zone of the banded lesions, often arranged linearly. The appearance of the fungus was consistent with a report from Sierra Leone and Guinea Conakry of a basidiomycete on maize of the order Agaricales, Marasmiellus paspalli (Petch) Singer (2). Lamellae were lacking, replaced on mature basidiomes by up to four ridges, which concurred with the description of an unnamed West African variety (1). The pileus and stipe of the mushroom were consistently white when fresh, and light beige when mature. The fungus grew readily on potato dextrose agar, forming a cottony white colony with occasional dark stromatic tissue, and hyphae with abundant clamp connections. Out of over 100 fields visited in 1993 and 1994, the disease was seen in one site only in southern Cameroon in 1994. In 1997, it was found in all maize fields in four separate areas in the southern humid forest zone of that country. In Ghana in November 1996, it was prevalent in a survey of 60 fields, with leaf area losses from 30 to 40%. In August of 1997, the disease appeared in low incidence on maize in Nigeria. The appearance of the Marasmiellus disease in Cameroon, Nigeria, and Ghana in the last 3 years represents a geographic shift from where the pathogen has been previously reported (1,2). It is not known at this time if significant yield loss is being incurred. References: (1) F. M. Latterell and A. E. Rossi. Plant Dis. 68:728, 1984. (2) M. M. Payak and R. C. Sharma. Curr. Sci. 55:1135, 1986.
First Report of Xylella fastidiosa on Catharanthus roseus in Brazil
Authors: Ueno B. , Funada C. K. , Yorinori M. A. , Leite R. P. 
Published: May 2007

In 1998, plants of periwinkle (Catharanthus roseus L.) showing small leaves, short internodes, and dieback symptoms were observed in a garden at the Instituto Agronomico do Parana (IAPAR), Londrina, PR, Brazil. Stems of these plants were cut into short sections and the sap extracted from the tissue by squeezing with pliers. The sap was blotted onto a glass slide and examined for the presence of bacteria by light microscopy (×400). Microscopy observations revealed the presence of a large number of slender, rod-shaped bacterial cells. The bacteria present in the stems of periwinkle were isolated on buffered cysteine-yeast extract (BCYE) and periwinkle wilt (PW) agar media. Stems were disinfected in 70% alcohol and cut into short sections, and the sap extracted as described above. The sap was blotted directly onto the media and the plates were incubated at 28°C. Typical colonies of Xylella fastidiosa were observed 10 days after isolation on both media. Indirect immunofluorescence tests with antibody specific to X. fastidiosa and anti-IgG conjugated with tetrametylrhodamine isothiocyanate (TRITC) were carried out with xylem sap of periwinkle stem and the isolated bacteria. In both cases, immunofluorescence tests were positive for X. fastidiosa. These results confirm that periwinkle plants were infected with X. fastidiosa. This is the first report of the association of X. fastidiosa with periwinkle plants in Brazil. However, the symptoms observed for the X. fastidiosa-infected periwinkle plants differed from those described previously in the U.S. (1): those symptoms consisted of marginal chlorosis and occasional vein clearing of leaves and wilting of the plants. Reference: (1) R. E. McCoy et al. Plant Dis. Rep. 62:1022, 1978.
First Report of Botryosphaeria dothidea Basal Canker of Pistachio Trees in South Africa
Authors: Swart W. J. , Blodgett J. T. 
Published: May 2007

Pistachio (Pistacia vera) cultivation is a relatively new industry in South Africa with tremendous economic potential. However, disease problems could develop in time. The pathogens of pistachio found in other parts of the world plausibly will spread to South Africa and new pathogens never recorded on this host may develop here. In the summer of 1998, 2-year-old rootstocks of P. atlantica and P. integerrima displaying basal cankers and discolored phloem and xylem were observed in the Prieska district of the Northern Cape province. The objective of this study was to identify the causal agent(s). Cankered stems were split and small samples of discolored wood were aseptically placed on corn-meal agar containing streptomycin and incubated for 5 days. Fungi that grew into the agar were transferred to 1.5% water agar dishes containing pine needles to aid sporulation. Species isolated from stems included Fusarium spp. (44%), Fusicoccum aesculi (anamorph of Botryosphaeria dothidea) (23%), a Cytospora sp. (19%), a Chaetomium sp. (3%), and several nonsporulating mycelial fungi (11%). Inoculum of suspected pathogens (F. aesculi, the Cytospora sp., and two Fusarium spp.) were prepared by culturing fungi in petri dishes on potato dextrose agar overlaid with sterile cheesecloth strips (approximately 15 × 25 mm) until the strips were completely colonized. Greenhouse inoculations involved wounding P. atlantica stems by removing the bark (approximately 3 × 6 mm) approximately 10 cm above the soil, and wrapping the colonized cheesecloth followed by Parafilm around the stems at the wound site. Eight plants per isolate and eight wounded and nonwounded (untreated) control plants were used. Noncolonized cheesecloth was applied to wounded controls but not to nonwounded controls. Treatments were assigned randomly. Eight weeks after inoculation, the surrounding bark was removed from all treated shoots and the cambium was examined for discoloration. The length of each cambial lesion was measured and stem sections were surface disinfested and transferred to 1.5% water agar dishes, and the presence of the inoculated fungi was confirmed. Only F. aesculi was pathogenic to P. atlantica and produced cankers on all stems. The fungus was recovered from all tissues sampled 3 cm beyond the wound sites, 88% of those sampled from the wound sites, and none of the control treatments. Discoloration of the phloem and xylem was similar to that observed in the field. The mean canker length was 41 mm on trees with a mean stem diameter of 7 mm. The appearance of B. dothidea, in addition to B. obtusa (1), on pistachio justifies the need for establishing a disease management program for pistachio in South Africa. Reference: (1) W. J. Swart and W.-M. Botes. Plant Dis. 79:1036, 1995.
Occurrence of the White Rust Pathogen, Albugo tragopogonis, in Seed of Sunflower
Authors: Viljoen A. , van Wyk P. S. , Jooste W. J. 
Published: May 2007

White rust of sunflower (Helianthus annuus L.), caused by Albugo tragopogonis (Pers.) S. F. Gray, appeared in South African fields not previously planted to sunflower. Spread to these fields from infested fields was unlikely, as some of the newly affected fields were planted out of season and were more than 300 km away from other sunflower production fields. Several reports of this nature led us to investigate the possibility of seed transmission of the causal organism. Extensive colonization of sunflower heads by A. tragopogonis was observed in field trials and breeding nurseries. Head infections consisted of two distinct lesion types. White rust pustules, typical of those formed on abaxial sides of leaves, were recognized on abaxial sides of involucral bracts. Grayish, localized lesions containing dark-colored oospores of the fungus, similar to those formed on stems and petioles (1), were produced in sub-epidermal tissue and extended 3 to 5 mm deep into receptacles. Colonization of seeds was found in only a few lines. Oospores were produced in the pericarps and testae of seeds. No oospores or hyphae, however, were observed in the embryo. This is the first report of A. tragopogonis being seed-borne. Since the incidence of seed infection is low, spread of disease to infested fields is expected to be insignificant. Of more concern, however, is the possible long-range dissemination of the fungus by means of infected seed into regions or countries where the disease has not been previously reported. Reference: (1) P. S. Van Wyk et al. Helia 18:83, 1995.