bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of Benomyl Resistance in Didymella bryoniae in Delaware and Maryland
Authors: Everts K. L. 
Published: May 2007

Gummy stem blight, caused by Didymella bryoniae (Auersw.) Rehm, is the most severe foliar disease of watermelon, Citrullus lanatus (Thunb.) Matsum. & Nakai, in eastern Maryland and southern Delaware. The fungicide benomyl is used in combination with chlorothalonil to manage gummy stem blight. Under conducive environmental conditions, yield losses are high even when fields are sprayed weekly. Resistance of D. bryoniae to benomyl has been reported in New York State and South Carolina (1). Gummy stem blight-infected leaves and stems were collected from nine and three fields in Wicomico County, MD, and Sussex County, DE, respectively, in 1996. Infected tissue was also collected from two Wicomico County fields in 1997. One single-spore subculture was obtained to represent each field. Agar plugs were taken from actively growing subcultures and inverted on a 25% (quarter strength) potato dextrose agar medium amended with 0 and 33.1 mg of benomyl per liter, the concentration of benomyl that reduced relative colony diameter of four resistant isolates in New York and South Carolina by 50% (1). Two replicate plates were used per experiment and each experiment was repeated once. After 6 days of growth at 21°C in the dark, the colony diameter was measured. Isolates were classified as sensitive if they were unable to grow, moderately sensitive if colony diameter was reduced 40 to 60%, and resistant if colony diameter was reduced less than 10% on the benomyl-amended media, compared with unamended media. Isolates that had previously been tested were used as sensitive (W03) and moderately sensitive (NY1) standards (1). In 1996, two isolates were sensitive, four isolates were moderately sensitive, and six isolates were resistant to benomyl. One isolate from 1997 was resistant and the other was moderately sensitive. This is the first report of resistance to benomyl within the D. bryoniae population in eastern Maryland and southern Delaware. Reference: (1) A. P. Keinath and T. A. Zitter. Plant Dis. 82:479, 1998.
First Report of Leaf Spot Caused by Alternaria alternata on Kiwifruit in Italy
Authors: Corazza L. , Luongo L. , Parisi M. 
Published: May 2007

A leaf spot of kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang & A. R. Ferg.) leaves was recently observed on plants of the cultivar Hayward in an orchard near Salerno, in southern Italy. The affected plants showed early severe defoliation. The fungus isolated from the infected leaves was identified as Alternaria alternata (Fr.:Fr.) Keissl., based on conidial morphological characteristics. Pathogenicity tests were made by inoculating detached leaves of male pollinator cultivar Tomuri and the female cultivars Hayward and Bruno with a 7-mm disk taken from actively growing cultures of the fungus on potato dextrose agar (PDA). After 14 days, necrotic leaf spots developed and A. alternata was consistently isolated from the inoculated leaves. A. alternata has been observed as a pathogen on leaves and fruits in New Zealand. In the Mediterranean, it has been reported in Israel (2) and in the island of Crete (1). This is the first report of Alternaria leaf spot on kiwifruit in Italy. References: (1) V. A. Bourbos and M. T. Skoudridakis. Petria 7:111, 1997. (2) A. Sive and D. Resnizky. Alon Hanotea 41:409, 1987.
First Report of Powdery Mildew of Greenhouse-grown Tomatoes in Alberta, Canada
Authors: Bains P. S. , Bennypaul H. , Mirza M. 
Published: May 2007

In Alberta, powdery mildew disease of greenhouse-grown tomatoes (Lycopersicon esculentum Mill.) appeared for the first time in 1995 as circular white colonies on leaves, petioles, and stems. Since then it has been found every year and is becoming an economically important disease of tomatoes. This is the first report of the disease from Alberta, Canada. In Canada, powdery mildew on greenhouse tomatoes was previously reported in 1994 from the province of Quebec (1). The pathogen had unbranched conidiophores with average length and width of 62.3 μm and 8.5 μm, respectively. Conidia were clear or hyaline, elliptical to oval in shape, and were borne singly or in short chains. Average length and width of conidia were 36.0 μm and 17.6 μm, respectively. The conidia contained numerous vacuoles but fibrosin bodies were not observed. Germ tubes were straight and formed at the ends or very close to the ends of conidia. Rarely, a conidium produced two germ tubes. Cleistothecia were not found. Six-week-old, greenhouse-grown, healthy tomato cv. Trust plants were inoculated by shaking conidia from powdery mildew-infected plants onto the leaves of the healthy plants. The plants developed powdery mildew symptoms within 9 days after the inoculation. The symptoms on inoculated plants and morphological characteristics of the pathogen were similar to those for naturally infected plants. Based on the characteristics of the asexual stage, the pathogen was identified as an Erysiphe sp. until its identity is confirmed by the characteristics of its sexual stage. An Erysiphe sp. has also been reported to cause powdery mildew of greenhouse-grown tomatoes in Canada (1), the U.S. (3), and Spain (2). Optimal temperature and relative humidity for germination of conidia of the pathogen were 20 to 25°C and >90%, respectively. Myclobutanil, fenarimol, sulfur, triademefon, and triforine showed promise for effective management of this disease. Myclobutanil and sulfur are now registered for control of this disease in Canada. Since cleistothecium has not been found, there is a need to identify the sources of primary inoculum to understand the disease cycle and effective management of the disease. References: (1) R. R. Bélanger and W. R. Jarvis. Plant Dis. 78:640, 1994. (2) L. Olalla and J. A. Torés. Plant Dis. 82:592, 1998. (3) J. F. White, Jr., et al. Plant Dis. 81:227, 1997.
First Report of Impatiens Necrotic Spot Tospovirus (INSV) in Israel
Authors: Gera A. , Kritzman A. , Cohen J. , Raccah B. 
Published: May 2007

In January 1999, Anemone coronaria L. imported from Europe and grown in open fields near Jerusalem in Israel developed foliar ringspots and foliar necrosis. Within a few weeks of the first appearance of these symptoms, further anemone plants in the surrounding area were affected and seriously damaged. Impatiens necrotic spot tospovirus (INSV) was detected in affected plants by enzyme-linked immunosorbent assay (ELISA; anti-INSV monoclonal antibodies were provided by H. T. Hsu, USDA, Beltsville, MD, and a polyclonal antibody to INSV was purchased from Loewe, Otterfing, Germany). Crude sap extracted from symptomatic tissue was mechanically transmitted to Emilia spp., Petunia hybrida, Nicotian glutinosa, N. benthamiana, and N. rustica plants that developed symptoms characteristic of INSV infection (1). ELISAs of leaf sap extracted from anemone plants and mechanically inoculated indicator plants gave a strong positive reaction to INSV. Leaf-dip preparations prepared from leaf samples of anemone plants were analyzed by transmission electron microscopy (TEM). Virus particles typical of a tospovirus were observed in samples taken only from symptomatic plants. TEM studies with ultrathin sections of infected anemone and Emilia spp. leaves revealed the presence of tospovirus-like particles. This first report of INSV interception in Israel brings the count of the Tospovirus members in Israel to three, including tomato spotted wilt virus (TSWV), which was found in the past to infect anemone and other ornamental crops, and the Iris yellow spot tospovirus, infecting onion (2). INSV is known to occur in Europe and in the U.S., mostly in flowers grown in greenhouses. The virus is transmitted by the Western flower thrips (WFT; Frankliniella occidentalis Pergande). Although all infected plants were destroyed, precautions to prevent further introduction of the virus must be made. INSV might spread by the WFT, which is abundant in Israel year round, and might also infect other greenhouse or field crops. References: (1) M. Daughtrey et al. Plant Dis. 81:1220, 1997. (2) A. Gera et al. Plant Dis. 82:127, 1998.
First Report of Sugarcane Yellow Leaf Virus in the French West Indies
Authors: Daugrois J. H. , Jean-Baptiste I. , Lockhart B. E. L. , Irey M. S. , Chatenet M. , Rott P. 
Published: May 2007

Unusually severe leaf yellowing symptoms, similar to those described for yellow leaf syndrome (1), have been observed in several sugarcane clones in Guadeloupe since 1994, and since 1997 in Martinique. Leaf samples exhibiting various types of yellowing were taken from five different sugarcane clones, and analyzed by immunosorbent electron microscopy. Spherical particles, 24 to 28 nm in diameter and characteristic of luteoviruses, were found in two of five samples. The two infected samples showed yellowing on the underside of the midrib and one had a pinkish coloration on the upper side. The presence of sugarcane yellow leaf virus (ScYLV), the causal agent of sugarcane yellow leaf disease, was confirmed by reverse transcription-polymerase chain reaction (2) in these two samples and in 36 of 184 sugarcane clones bred in Guadeloupe and sent to Cirad's quarantine station in Montpellier, France. Following these observations, surveys were undertaken with a tissue blot enzyme immunoassay to analyze the distribution of ScYLV in sugarcane clones in the French West Indies. The midrib base of the first visible dewlap leaf was used to detect the presence of the virus in the phloem. In a first survey, clones of various origins worldwide were taken from germplasm collections. Two to three leaf samples per clone were analyzed from 78 clones in a collection in Guadeloupe and from 36 in a collection in Mar-tinique. Fifty of the 114 clones were infected by ScYLV, and ScYLV was detected in 21 of the 32 clones exhibiting severe leaf yellowing (score 3 or higher on a 1 to 5 scale). In a second survey, 19 leaf samples were taken from each of 53 clones from plants produced by Cirad's breeding program in Guadeloupe. The virus was detected in at least one sample for 25 of these 53 clones. ScYLV incidence in commercial fields was tested in Martinique in the variety B5992, which constitutes 57% of the cultivated area. Twenty leaves from different stools were sampled in six different fields, five of which had ScYLV-infected plants. The percentage of virus-infected stalks ranged from 0 to 90% whereas the percentage of stalks showing symptoms ranged from 50 to 100%. ScYLV appears widespread in the French West Indies, perhaps because a vector (Melanaphis sacchari) exists in Martinique and Guadeloupe. However, ScYLV was not found in all symptomatic plants, indicating that even if this luteovirus is a causal agent of leaf yellowing in the French West Indies, there may be other causal agents as well. References: (1) J. C. Comstock et al. Sugar J. 3:33, 1994. (2) J. C. Comstock et al. Sugar Cane 4:21, 1998.
First Report of Myrothecium verrucaria from Muskmelon Seeds
Authors: Belisario A. , Forti E. , Corazza L. , van Kesteren H. A. 
Published: May 2007

Myrothecium verrucaria (Albertini & Schwein.) Ditmar:Fr. was isolated from muskmelon (Cucumis melo L.) seeds of Charentais-T, a culti var used as a differential host with no resistance to Fusarium oxysporum f. sp. melonis races. A white floccose mycelial mat developed on melon seeds during incubation on moist blotters. Mycelia were mass transferred from melon seeds onto potato dextrose agar (PDA) medium. At 25°C in the dark, a mycelial mat with characteristic annelations of greenish-black sporodochia, without setae, was produced. Conidia (2 to 3 × 6 to 10 μm) were lemon shaped, with a typical conical mucous appendage at one end, which was visible with Loeffer's flagella stain (1). Based on these characteristics, the fungus was identified as M. verrucaria. For pathogenicity studies, surface sterilized seeds of C. melo cv. Charentais-T were coated with M. verrucaria conidia by gently rubbing the seeds on sporodochia produced on 15-day-old cultures on PDA. Once coated, seeds were plated onto water agar and on sterile moist blotters in 9-cm-diameter petri dishes. Plates were incubated at 28°C in the dark. Five seeds per plate and three plates per experiment were used. Experiments were replicated three times. Control seeds were plated without coating. After 7 days, on water agar, 90% of melon seeds failed to germinate while the remaining 10% produced young seedlings that died from root rot and necrotic lesions on the hypocotyl. After 12 days on moist blotters, 100% of the melon seedlings died, showing necrotic lesions on the hypocotyl and on the main root. The pathogen was reisolated from symptomatic melon seedlings. All control seeds germinated and grew into healthy seedlings. M. verrucaria, known to be a seed-borne pathogen, has been isolated from soil and plants worldwide (2). This is the first report of M. verrucaria pathogen on muskmelon. This fungus is not a serious concern when seeds are dressed with fungicides. References: (1) K. V. A. Thompson and S. C. Simmens. Nature. 193:196, 1962. (2) S.-M. Yang and S. C. Jong. Plant Dis. 79:994, 1995.
First Observation of Xanthomonas campestris pv. vesicatoria Race T2P7 Isolated from Pepper in the Philippines
Authors: Sahin F. , Kotan R. , Gergon E. , Miller S. A. 
Published: May 2007

Thirteen strains of Xanthomonas campestris pv. vesicatoria, causal agent of bacterial spot of pepper (Capsicum spp.) and tomato (Lycopersicum spp.), were isolated from six different pepper fields in the vicinity of Bongabon, Luzon, the Philippines. The strains were characterized based on sensitivity to copper and streptomycin, physiological tests, analysis of whole cell fatty acids (fatty acid methyl ester; FAME), serology, amplification of the 16S–23S rDNA spacer region, pathogenicity, and virulence on pepper and tomato differential genotypes as previously described (1,2). All of the Philippine strains were copper resistant (50 μg/ml), and streptomycin sensitive (20 μg /ml). None of the strains were pectolytic or amylolytic. FAME analysis showed that all strains had similar fatty acid profiles, and matched the strains to X. campestris (similarity indices [S.I.] = 0.186–0.455). With the universal primers 4F/7R, a DNA fragment (680 bp) was amplified from 16S–23S rDNA spacer regions of all Philippine strains. Serological fingerprints of the strains with a set of eight monoclonal antibodies (MAbs) in indirect enzyme-linked immunosorbent assay showed that all Philippine strains were serovar A1. Existence of the avrRxv gene in X. campestris pv. vesicatoria race T1 strains was also confirmed for all Philippine strains by amplifying a DNA fragment (approximately 0.7 kb) with the primer set RST 27/28. This is genetic evidence for race identity of the Philippine strains with T1. However, hypersensitive test results on pepper and tomato differential lines identified the Philippine strains as T2P7. These results showed that X. campestris pv. vesicatoria strains may contain the avrRxv gene, but it may not be functional. This is the first report of the observation of X. campestris pv. vesicatoria race T2P7 on pepper. References: (1) H. Bouzar et al. Phytopathology 84:664, 1994; (2) F. Sahin and S. A. Miller. Plant Dis. 82:794, 1998.
Recent Outbreak of Soybean Sudden Death Syndrome in Iowa
Authors: Sanogo S. , Yang X. B. 
Published: May 2007

Sudden death syndrome (SDS) of soybean, caused by Fusarium solani f. sp. glycines, was first found in four Iowa counties in 1993 at low intensities. Following the first report of the disease, a statewide survey in 1994 and 1995 showed an overall low prevalence of the disease, mainly in eastern Iowa (2). In 1998, an epidemic of the disease occurred with drastic increases in prevalence and severity at regional, local, and field levels. The disease was found in 31 Iowa counties covering five out of the nine Iowa crop-reporting districts, with expansion in occurrence northward and westward. There were 12 SDS-affected counties in the North Central and Central districts, and 19 in the East Central, Southeast, and Northeast districts. To assess the extent of SDS increase at the local level, extensive surveys were conducted in 1998 in three areas where previous surveys were made in 1994 or 1995. In Washington County (Southeast District), the frequency of infestation has increased from 5% (2 of 40 fields surveyed) in 1995 to 30% in 1998. In Black Hawk County (East Central District), 26% of the fields examined had SDS, compared with 4.5% in 1995 (2 of 44 fields). In Story County (Central District), 35% of soybean fields were found with SDS in 1998, as opposed to 3% (2 of 62 fields) in 1994. In previous surveys (2), large disease patches (about 1 ha) were not found in central Iowa and were mainly limited to eastern counties along the Mississippi River. However, approximately 30% of the infested fields surveyed in 1998 had two to five patches with areas from 0.5 to 2.5 ha. The remaining 70% of the fields had several patches of diseased soybean plants with areas ranging from 3 m2 to 0.5 ha. The largest disease patch observed was about 10 ha, covering half of a field in Black Hawk County. Percentage of field area affected by SDS varied from 3 to 15% in 60% of the fields where the disease was found, and from about 20 to 60% in the remainder. In all fields surveyed, SDS was confirmed based on the presence of bluish sporulation or isolation from taproots of representative plants. The outbreak supports the 1996 risk assessment (1) that SDS would become a major production concern in Iowa. References: (1) H. Scherm and X. B. Yang. Phytopathology 87:S86, 1997. (2) X. B. Yang and P. Lundeen. Plant Dis. 81:719, 1997.
A New Pathotype of Puccinia striiformis f. sp. tritici on Wheat in South Africa
Authors: Boshoff W. H. P. , Pretorius Z. A. 
Published: May 2007

Following the detection of Puccinia striiformis f. sp. tritici for the first time on wheat (Triticum aestivum) in the Western Cape in August 1996, stripe rust has spread to all the important wheat production areas in South Africa. Only the introduced pathotype (pt. 6E16) was detected in surveys of these areas during 1996 and 1997. In 1998, a severe stripe rust epidemic occurred in the eastern Free State on the extensively grown cultivars Hugenoot and Carina, both which are resistant to pt. 6E16. Stripe rust severities of 100% were common on flag and lower leaves, and widespread applications of fungicides were necessary. Avirulence/virulence characteristics of P. striifomis f. sp. tritici isolates collected from Hugenoot and Carina were determined on 17 standard stripe rust differential wheat lines and 11 supplementary testers. The latter testers included the wheat lines TP981 and TP1295 (supplied by R. Johnson, Cambridge, UK), both of which have a major resistance gene in common with the differentials Heines Peko, Reichersberg 42, Strubes Dickkopf, Clement, and Heines VII (1). Isolates obtained from Hugenoot and Carina differed from pt. 6E16 based on virulence to Reichersberg 42 (Yr7,25), Heines Peko (Yr2,6,25), TP981 (Yr25), and TP1295 (Yr25). The new variant, designated as 6E22, was also identified in collections from the province KwaZulu-Natal. Seedling tests with 6E16 and 6E22 have shown that Hugenoot, Carina, and Tugela-DN are the only local cultivars affected by the new pathotype. The occurrence of pt. 6E22, which appears to be a single-step adaptation from 6E16 adding virulence to Yr25, emphasizes the vulnerability of monogenic resistance to this disease. Reference: (1) R. A. McIntosh et al. Wheat Inform. Serv. 85:56, 1997.
First Report of Root and Collar Rot by Sclerotium rolfsii on Apple Trees in Italy
Authors: Corazza L. , Belisario A. , Forti E. 
Published: May 2007

Sclerotium rolfsii Sacc. (teleomorph Athelia rolfsii (Curzi) Tu & Kimbrough) is a polyphagous, soilborne plant pathogen. In summer 1998, a sudden death of 2-year-old apple trees (Malus domestica Borkh.) cv. Royal Gala grafted on M9 rootstock was observed in an orchard near Rome, Italy. Symptoms were stunted vegetation, leaf chlorosis, and root and collar rot. A fungus identified as S. rolfsii was observed producing sclerotia and whitish mycelial strands on root and collar bark. Isolations from roots and at the margin of subcortical necrosis on the collar consistently yielded S. rolfsii colonies on potato dextrose agar (PDA); sclerotia developed within 7 days. Koch's postulates were fulfilled by inoculating 10 1-year-old apple tree cv. M9 rootstocks, grown in 3.5-liter pots, with an S. rolfsii isolate grown for 1 week on PDA at 25°C. One ground plate per plant was used, placed around collar and main roots. Five control plants were treated with PDA only. Rootstocks were kept in the greenhouse at 26 ± 2°C. Within 2 months, 70% of inoculated plants died, with marked necrosis girdling the collar. The other inoculated plants showed a general decline, with widespread necrosis on collars and main roots. Control plants remained healthy. S. rolfsii was reisolated from collars and roots of symptomatic plants. S. rolfsii has been recorded on apple trees in the U.S., India, China, and Israel. In Italy, it is destructive on several crops, and was recently recorded on walnut (1). This first outbreak of S. rolfsii on apple in Italy may have been favored by exceptionally warm late spring and summer temperatures. Reference: (1) A. Belisario and L. Corazza. Plant Dis. 80:824, 1996.
First Report of the Green Rosette Variant of Groundnut Rosette Disease in Kenya
Authors: Wangai A. W. , Pappu S. S. , Pappu H. R. , Okoko N. , Deom C. M. , Naidu R. A. 
Published: May 2007

Groundnut (Arachis hypogaea L.) is an important food crop in sub-Saharan Africa. One of the major production constraints is groundnut rosette disease, which is caused by a complex of two viruses, groundnut rosette assistor luteovirus (GRAV) and groundnut rosette umbravirus (GRV) together with the associated satellite RNA (satRNA) (1). Two main forms of the disease have been described: chlorotic and the green rosette. Variants of the satRNA have been shown to be largely responsible for the different forms of the disease (1). Chlorotic rosette has been the predominant form in all of sub-Saharan Africa while green rosette has been reported in the western and southern regions of Africa (2). During the 1997-1998 crop season, disease surveys conducted in Kenya showed the incidence of the rosette disease in farmers' fields to be 24 to 40% in a total of 23 fields surveyed in the western regions of the country (Homabay, Kendubay, Kisumu) and 30% in 8 fields sampled in the Rift Valley (Cheplamus, Marigat) regions. Representative peanut plants showing rosette symptoms were analyzed for the presence of GRV by reverse transcription polymerase chain reaction (RT-PCR). With primers specific to a portion of ORF4 of GRV RNA (3), RT-PCR gave a product of expected size (approximately 300 bp). The PCR product was cloned in pGEM-T vector and sequenced. The sequenced region showed 89% nucleotide sequence identity with published GRV sequences. Green rosette was observed on groundnut cultivars Nyaela Red and Homabay Local in the Kendu Bay region. The incidence of the green rosette was 5.3% of the plants with rosette symptoms. References: (1) A. F. Murant and I. K. Kumar. Ann. Appl. Biol. 117:85, 1990. (2) R. A. Naidu et al. Ann. Appl. Biol. 132:525, 1998. (3). M. E. Taliansky et al. J. Gen. Virol. 77:2335, 1996.