bluuebunny/crossref_metadata_2025 huggingface dataset:
First Report of the Prevalence of Benzimidazole-Resistant Isolates in a Population of Cylindrocladium pauciramosum in Italy
Authors: Polizzi G. , Vitale A.
Published: May 2007

Cylindrocladium pauciramosum C.L. Schoch & Crous (teleomorph Calonectria pauciramosa C.L. Schoch & Crous), described as a member of the Cylindrocladium candelabrum Viégas complex (4), was recently reported from Europe (3). In southern Italy, the fungus has caused extensive losses, and chemical control measures are necessary, especially in ornamental nurseries. Several researchers have found benzimidazole fungicides to be effective for control of different species of Cylindrocladium, however, in fungicide trials conducted on myrtle plants infected by C. pauciramosum, benomyl was ineffective (2). Another study showed that mycelial growth of six isolates was completely inhibited by carbendazim at a concentration of 1 μg a.i./ml whereas, concentrations of 10, 100, and 500 μg a.i./ml did not completely inhibit growth of four isolates (1). To examine benzimidazole resistance in C. pauciramosum, 200 single-conidia isolates were tested. These were collected during 1996 and 1997 from several symptomatic hosts in different nurseries located in Sicily and Calabria and identified through morphological characteristics as well as mating-type studies with tester strains. Sensitivity to benomyl was determined by plating mycelial plugs on potato dextrose agar (PDA) amended with benomyl at 1, 10, 100, and 500 μg a.i./ml. For 20 benomyl-resistant isolates, fungal growth was also determined at the same concentrations on carbendazim-amended PDA. Sensitivity was expressed as the minimum inhibitory concentration (MIC) (the lowest fungicide concentration that completely prevented fungal growth). Isolates that did not grow on benzimidazole-amended PDA were classed as sensitive. Isolates were considered resistant to benzimidazole if MIC values were greater than 1 μg a.i./ml. Of the 200 isolates tested, 58% were resistant to benomyl. The benomyl-resistant isolates tested for carbendazim sensitivity were cross-resistant to carbendazim. Most resistant isolates grew in the presence of benomyl at 500 μg a.i./ml. On agar culture, the isolates were either the fast-growing or slow-growing type. The slow-growing phenotype appears to be related to the higher level of resistance (500 μg a.i./ml). On the basis of these data, the use of benzimidazole for the control of this pathogen should be seriously questioned. To our knowledge, this is the first report of the prevalence of benzimidazole resistance in a population of C. pauciramosum.

References: (1) G. Polizzi. Inf. Fitopatol. 11:39, 2000. (2) G. Polizzi and A. Azzaro. Petria 6:117, 1996. (3) G. Polizzi and P. W. Crous. Eur. J. Plant Pathol. 105:407, 1999. (4) C. L. Schoch et al. Mycologia 91:286, 1999.
Differentiation of aFusicoccumsp. Causing Panicle and Shoot Blight on California Pistachio Trees fromBotryosphaeria dothidea
Authors: Smith Denise R. , Michailides Themis J. , Stanosz Glen R.
Published: May 2007

A panicle and shoot blight disease of pistachio trees in California is caused by a fungus previously identified as the anamorph of Botryosphaeria dothidea. We have compared random amplified polymorphic DNA (RAPD) markers, nuclear rDNA internal transcribed spacer (ITS) region sequences, and conidium morphology of 15 isolates of the pistachio Fusicoccum to those of well-characterized isolates of B. dothidea, B. ribis, and F. luteum. Cluster analysis of RAPD markers separated the pistachio Fusicoccum isolates from B. dothidea, as did parsimony analysis of the ITS region sequences. Conidium size and shape were similar to those of B. ribis (Fusicoccum sp.) and F. luteum, but distinguishable from those of F. aesculi (the anamorph of B. dothidea). We conclude that the fungus causing panicle and shoot blight of pistachio is distinguishable from B. dothidea and is part of a complex containing B. ribis, F. luteum, and other fungi with Fusicoccum anamorphs.
First Report of Powdery Mildew Caused by Podosphaera leucotricha on Prunus africana in Kenya
Authors: Mwanza E. J. M. , Waithaka S. K. , Simons S. A.
Published: May 2007

Prunus africana, formerly known as Pygeum africanum, is widely distributed in moist, tropical Africa and produces durable timber. Extracts from its bark are used in treatment of prostate disorders. Powdery mildew was observed on nursery-grown seedlings of P. africana in Kenya (Nyeri, Kiambu, and Kericho districts) in the dry seasons of 1998, 1999, and 2000. White ectotrophic mycelial growth was observed on leaves. The fungus caused stunting, distortion of leaves, surface necrosis of invaded tissues, and general decline in growth of seedlings that led to premature leaf fall and death. Invaded leaflets wilted and dropped, leaving behind a bare stem. The primary mycelium was hyaline, with no secondary brown mycelium. The conidial state was conspicuous, with conidia produced in chains. Appressoria were unlobed and nipple shaped. Conidiophores were straight and three-celled, measuring 75 to 112 μm. Conidiophore foot cells were topped by a longer cell and one or two shorter cells measuring 35 to 77 μm. Conidia had fibrosin bodies, were ovoid, and measured 27 to 30 × 17 to 18 μm. The fungus was identified by the International Mycological Institute IMI (W6496) as Podosphaera leucotricha (Ellis & Everh.) E. S. Salmon. Infected leaves of P. africana were deposited at the East African Herbarium, National Museums of Kenya (Accession No. KM-KEFRI/446/2001). Pathogenicity was confirmed by inoculating seedlings of P. africana by gently pressing infected leaves with abundant sporulation onto healthy leaves. The plants were then incubated under moist conditions for 48 h and thereafter maintained in a glasshouse. After 15 days, powdery mildew symptoms developed on seedlings. Examination of leaves confirmed that they were infected with Podosphaera leucotricha. Uninoculated control plants were free of powdery mildew. To our knowlege, this is the first report of Podosphaera leucotricha as a pathogen of P. africana.

Reference: 1. H. J. Boesewinkel. Bot. Rev. 46:167, 1980.
First Report of Frog Skin Disease in Cassava (Manihot esculenta) in Venezuela
Authors: Chaparro-Martínez E. I. , Trujillo-Pinto G.
Published: May 2007

Frogskin disease (FSD) is a disease of clonally propagated cassava (Manihot esculenta Crantz) and has been reported to reduce cassava yields significantly in South America (1). FSD is caused by an uncharacterized virus that is restricted to South America. The evidence indicates FSD is transmitted by stem cuttings and graft (3). However, little information is available on its distribution and incidence in Venezuela. Eighty-seven samples with virus-like symptoms were collected with the help of technical staff and producers in cassava-producing states: Amazonas (1 sample), Aragua (7 samples), Barinas (35 samples), Cojedes (8 samples), Monagas (19 samples), and Portuguesa (17 samples). In these states, the average daytime temperature was 26°C, but the average was higher (>28°C) during the dry season. Samples were collected during the rainy season because high temperatures and dry field conditions appeared to suppress symptom expression, while cooler conditions tended to favor symptom development (2). Roots of sampled cassava plants were examined for the presence of FSD. A single 70- to 80-cm-long stem cutting was taken from each plant and subdivided into four pieces. Two pieces were used as rootstocks in graft-inoculation tests with Secundina scions for FSD detection, and two pieces were potted in sterilized soil to be used in other tests. All potted and grafted plants were kept in the Vegetable Virology Laboratory of the Faculty of Agronomy (Universidad Central de Venezuela), at an average temperature of 24°C and 80% relative humidity. FSD-infected plants were identified by mosaic symptoms on Secundina scions and the presence of 80-nm spherical viral particles. Most FSD-infected cultivars expressed only root symptoms. However, in the case of Secundina cvs. MCOL 22 and MCOL 113, foliar symptoms were also detected (1). FSD was found in a simple infection in one cassava sample from Aragua State (14.3% incidence, 1 of 7 samples) and in four cassava samples from Barinas State (11.4% incidence, 4 of 35 samples) associated with Cassava virus X (detected by double-antibody sandwich enzyme-linked immunosorbent assay). To our knowledge, this is the first report of FSD detection in Venezuela.

References: (1) E. A. Frison et al. Informe Anual. CIAT, Cali, Colombia, 1995. (2) B. L. Nolt et al. Plant Pathol. 41:384, 1992. (3) Technical Guidelines for the Safe Movement of Cassava Rome. FAO/IBPGR. p. 10-27, 1991.
First Report of a Tospovirus Infection of Peanuts in Iran
Authors: Golnaraghi A. R. , Shahraeen N. , Pourrahim R. , Ghorbani Sh. , Farzadfar Sh.
Published: May 2007

During the summer of 2000, severe stunting, mosaic, bud necrosis, and chlorosis symptoms were observed on peanut (Arachis hypogaea cv. Gilan) plants growing in fields in the Golestan Province of Iran. Leaf extracts of peanut plants were infective (mechanical inoculation) causing necrotic local lesions on Chenopodium quinoa, C. amaranticolor, Gomphrena globosa, Phaseolus vulgaris cv. Talash, Vicia faba, and Vigna unguiculata cv. Mashad; systemic chlorotic spots were followed by systemic necrosis in Datura stramonium, D. metel, and Nicotiana rustica; chlorotic and necrotic spots were followed by top necrosis in Glycine max. About 2 weeks after inoculation, the chlorosis followed by stunting and bud necrosis observed in the field were reproduced in A. hypogaea cv. Gilan. Tomato spotted wilt virus (TSWV) was detected in the original peanut plants and in plant species that developed symptoms after inoculation with extracts from peanut plants, when analyzed by double-antibody sandwich enzyme-linked immunosorbent assay using TSWV-specific antisera (polyclonal antibody As-0526 and As-0580, DSMZ, Braunschweig, Germany). TSWV is one of the most important viruses in the world (2) and has been reported on potato (3) and tomato (1) in Iran. To our knowledge, this is the first report of TSWV infection of peanut in Iran.

References: (1) K. Bananej et al. Iran. J. Plant Pathol. 34:30, 1998. (2) R. A. Mumford et al. Ann. Appl. Biol. 128:159, 1996. (3) R. Pourrahim et al. Plant Dis. 85:442, 2001.
First Report of Rhizoctonia solani AG-4-HG-II on Garden Pink in Buenos Aires, Argentina
Authors: Wright E. R. , Rivera M. C. , Asciutto K. , Gasoni L.
Published: May 2007

During 2001, basal stem rot, wilt, and plant death were observed on 30% of the plants in a crop of Dianthus plumarius L. ‘Telstar’ in Buenos Aires. Pieces of diseased stems ≈1 cm long were surface-disinfested in 2% NaOCl for 1 min and cultured on 2% potato dextrose agar (PDA), pH 7, at 22 to 24°C. After 7 days, an identical fungus was consistently isolated from pieces of infected tissue. Colonies initially were white, turned brown after 2 to 3 days, and eventually formed irregularly shaped sclerotia. Cultures exhibited morphological characteristics typical of Rhizoctonia solani Kühn (2) and were identified with known anastomosis group tester isolates (1). Positive anastomosis was observed with tester strains of R. solani AG-4-HG-II. One isolate was tested for pathogenicity by placing two pieces of PDA (1 cm2) containing 7-day-old mycelial growth ≈0.5 cm from the base of healthy 2-month-old plants. Control plants were treated with sterile pieces of PDA using the same procedures. Ten replicate plants were used for each treatment. Plants were maintained at 22 to 24°C under 95 to 100% relative humidity and a 12-h light/dark photoperiod. After 7 days, symptoms developed that were similar to those originally observed, and Koch's postulates were satisfied by reisolating the fungus. To our knowledge, this is the first report of R. solani AG4-HG-II causing disease on D. plumarius in Argentina.

References: (1) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN, 1991. (2) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.
First report of Beet virus Q in Belgium
Authors: Stas A. , Meunier A. , Schmit J.-F. , Bragard C.
Published: May 2007

Beet necrotic yellow vein virus (BNYVV), the causal agent of rhizomania disease on sugar beet, has been reported in Belgium for more than 16 years. Other soilborne viruses belonging to the genus Pomovirus, such as Beet soilborne virus (BSBV) (3) and Beet virus Q (BVQ) (1), are suspected pathogens of sugar beets grown in Belgium. During the 2000 growing season, more than 20 fields showing rhizomania-like and yellowing symptoms on sugar beet leaves were investigated for the presence of BVQ, BNYVV, and BSBV. All samples were checked by enzyme-linked immunosorbent assay (ELISA) using commercial BNYVV (Sanofi Diagnostics Pasteur, Marnes-La-Coquette, France) and BSBV/BVQ (DSMZ, Braunschweig, Germany - AS-0576 polyclonal, AS-0576/2 MAb) antisera. RNA was extracted from sugar beet rootlets using an RNeasy extraction kit (Qiagen, Hilden, Germany), before performing a reverse transcription-polymerase chain reaction (RT-PCR) using primers (5′-GCTGGAGTATATCACCGATGAC-3′ and 5′-AAAATC TCGGATAGCATCCAAC-3′) designed to specifically amplify a 510-bp region of BVQ RNA-1. The presence of BSBV and BNYVV was also checked by RT-PCR using previously described primers (1,2). The BVQ-derived PCR product was sequenced and proved to be more than 99% identical to the Wierthe BVQ isolate nucleotide sequence. Soil transmission of BVQ was demonstrated through a bioassay using soil dilutions with quartz and sugar beet cv. Cadyx as bait. After 6 weeks, BVQ was detected by RT-PCR in bait plants. The putative vector, Polymyxa betae, was identified by lactophenol-cotton blue staining of the roots followed by microscopic examination. BVQ produces irregularly shaped local lesions that appear ≈5 days after mechanical inoculation and tend to spread along veins. BVQ was detected in six fields located in the Polders Region and Brabant Province of Belgium. BVQ was always found in sugar beet samples coinfected with BNYVV and BSBV. The economic significance of BVQ and its interaction with other viruses is not known.

References: (1) R. Koenig et al. J. Gen. Virol. 79:2027, 1998. (2) M. Saito et al. Arch. Virol. 141:2163, 1996. (3) M. Verhoyen and M. Van den Bossche. Parasitica. 44:71, 1987.
First Report of Rust Caused by Puccinia allii on Wild Garlic in California
Authors: Koike S. T. , Smith R. F.
Published: May 2007

Wild garlic (Allium vineale) is a bulbous perennial weed that was introduced from Europe and is now established throughout the eastern and much of the western United States. In 2001, wild garlic plants growing in Monterey County, CA were infected with a rust fungus. Uredinia and telia were present on leaves, resulting in small (2 to 5 mm long) lesions; however, leaf dieback and other symptoms were not observed. The orange urediniospores were spherical to ellipsoidal, echinulate, and mea-sured 26 to 30 × 25 to 28 μm. Telia were black in mass and divided into locules by fused paraphyses. Teliospores were located within the locules and were brown, smooth-walled, two-celled, and measured 40 to 50 × 17 to 20 μm. Teliospore pedicels were hyaline, usually fractured, and measured 3 to 15 μm. One-celled mesospores were not observed. Based on these morphological characteristics, the pathogen was identified as Puccinia allii (1,2). To our knowledge, this is the first report of rust caused by P. allii on wild garlic in California. Because of this finding, an experiment was designed to determine whether wild garlic could be a source of rust inoculum for commercial allium crops. Wild garlic bulbs were planted in 4-in. pots (10 cm square) and grown in a greenhouse. At the 4- to 5-leaf stage the plants were transplanted in a garlic (Allium sativum) cultivar trial that had been inoculated with an isolate of P. allii from garlic. When plants were evaluated 2 months later, uredinia and telia were observed on the wild garlic plants, and the fungus was confirmed to be P. allii. Wild garlic, therefore, could be a source of overwintered inocula for the rust disease that occurs on commercial garlic and onion (A. cepa) in California (2).

References: (1) D. M. Jennings et al. Mycol. Res. 94:83, 1990. (2) S. T. Koike et al. Plant Dis. 85:585, 2001.
First Report of Powdery Mildew on Greenhouse Tomatoes Caused by Oidium neolycopersici in Florida
Authors: Marois J. J. , Momol M. T. , Kimbrough J. W. , Hochmuth R. C. , Dankers W.
Published: May 2007

In December 1999, typical signs of powdery mildew-dense white mycelium in irregular patterns often covering almost the entire upper surface of leaves-were observed in production greenhouses on tomato cv. Tradiro. Microscopic observations revealed mycelium with lobed appressoria and large, approximately cylindrical conidia that measured 38 to 45 × 16 to18 μm. Short germ tubes were at one end of the conidium and ended in a lobed appressorium. Conidiophores were straight with cylindrical foot-cells (≈40 to 42 μm), followed by two short cells (14 to18 μm). Based on these characteristics the fungus was identified as 0idium neolycopersici Kiss et al. (2) (formerly O. lycopersicum Braun [1]). Disease-free tomato cv. FL47 plants were inoculated at the fourth true-leaf stage with conidia by transferring fungal colonies collected from plants in production greenhouses with a single-edged razor blade to the adaxial surface of the test plants (six plants and three leaves per plant). Plants were grown in the greenhouse at 20 to 25°C. Powdery mildew, exhibiting the same morphological features, was observed 12 days later on inoculated tomato leaves. Powdery mildew on tomatoes in Suwannee Valley area greenhouses in Florida was quite common and severe in 1999 to 2000. Secondary cycles of the disease were observed, resulting in disease incidence up to 50 to 60% in some greenhouses, requiring repeated applications of sulfur for its management. This disease is expected to become a significant problem in greenhouse tomatoes, requiring regular disease control measures. This powdery mildew has not yet been observed in field-grown tomatoes in Florida. The pathogen has been reported in Connecticut on tomatoes grown under greenhouse and field conditions (3). To our knowledge, this is the first report of O. neolycopersici on greenhouse-grown tomatoes in Florida.

References: (1) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fisher Verlag, New York, 1995. (2) L. Kiss et al. Mycol. Res. 105:684, 2001. (3) J. A. LaMondia et al. Plant Dis. 83:341, 1999.
Leaf Spot Disease of Spinach in California Caused byStemphylium botryosum
Authors: Koike Steven T. , Henderson Diana M. , Butler Edward E.
Published: May 2007

Beginning in 1997, a new disease of spinach was found in the Salinas Valley, Monterey County, CA. Initial symptoms were leaf spots that were 2 to 5 mm in diameter, circular, and gray-green in color. Spots later enlarged, turned tan in color, and became dry and papery in texture, resembling phytotoxicity due to agrichemicals. Although fungal signs were generally absent from the spots, Stemphylium botryosum was consistently isolated and caused identical symptoms when inoculated onto 20 spinach cultivars. Three isolates did not cause disease symptoms when inoculated onto other crop plants representing 16 different genera and a Chenopodium weed species. A fourth isolate showed similar results with the exception of small leaf spots occurring on inoculated fava bean. Isolates produced a Pleospora herbarum teleomorph after 7 months incubation at 5°C. Preliminary experiments with cell-free culture filtrates indicated that phytotoxins apparently were not produced by these isolates. This is the first report of a foliar spinach disease caused by S. botryosum.
Resistance to Triadimefon and Benomyl: Dynamics and Impact on Managing Cucurbit Powdery Mildew
Authors: McGrath Margaret Tuttle , Shishkoff Nina
Published: May 2007

Frequency of fungicide-resistant strains of Podosphaera xanthii on pumpkins in New York before treatment varied from 3 to 80% for the demethylation inhibiting (DMI) fungicide triadimefon and from 0 to 48% for the benzimidazole fungicide benomyl between 1993 and 1996. When the initial frequency of triadimefon-resistant strains was less than 55%, one application of triadimefon plus chlorothalonil was effective. This application was made after reaching the action threshold of one leaf with powdery mildew symptoms per 50 old leaves (defined as the oldest third of the foliage). The frequency of triadimefon-resistant strains increased from 3 to 71% by 20 days after the first fungicide application in 1993. Triadimefon in the second application did not contribute to control. Loss of efficacy was due to resistance because, compared with triadimefon-treated pumpkins, pumpkins treated with other systemic fungicides were less severely infected by powdery mildew on abaxial leaf surfaces where the companion multi-site contact fungicide contributes little to control. Triadimefon was not effective in 1995 when 80% of the pathogen population was resistant before treatment. Benomyl was effective in 1995, but not in 1996 when 48% of the isolates tested were resistant to both benomyl and triadimefon before treatment. An in-field seedling assay was developed to determine local occurrence of resistant strains before the first treatment was needed. Although sensitivity of the pathogen population to the DMI fungicides myclobutanil and propiconazole also decreased after they were applied, these fungicides were more effective than triadimefon.
Physiologic Specialization of Puccinia triticina in Canada in 1998
Authors: Kolmer J. A.
Published: May 2007

In 1998, leaf rust of wheat (Triticum aestivum), caused by Puccinia triticina, was widespread throughout the prairies of western Canada. Warm summer temperatures with frequent dew periods favored spread of the disease in wheat fields in Manitoba and Saskatchewan. The Canada Prairie Spring wheat cultivars (AC Vista, AC Foremost, AC Crystal) were susceptible to leaf rust, while the bread wheat cultivars with leaf rust resistance genes Lr16 and Lr13 or Lr34 (AC Majestic, AC Domain, AC Barrie) had high to moderate levels of leaf rust infections. Bread wheat cultivars AC Cora, AC Minto, Pasqua, and McKenzie had trace to low levels of leaf rust infection. Thirty-four virulence phenotypes of P. triticina were identified on 16 Thatcher lines, which are near-isogenic for leaf rust resistance genes. Phenotypes with virulence to Lr16 increased to 25% of isolates in Manitoba and Saskatchewan in 1998. Forty-three isolates were also tested for virulence to plants with the adult plant resistance genes Lr12, Lr13, Lr34, and Lr13,34. Most isolates had virulence to Lr12 and Lr13. All isolates had lower infection type on adult plants with Lr34 compared with Thatcher.
Overwinter Survival of Bean Rust Urediniospores in North Dakota
Authors: Gross P. L. , Venette J. R.
Published: May 2007

Bean rust (Uromyces appendiculatus) reached epidemic proportions in North Dakota and Minnesota from 1993 to 1996. Although U. appendiculatus is a macrocyclic autoecious rust, neither pycnia nor aecia have been observed in commercial dry bean (Phaseolus vulgaris) in North Dakota fields. The source of initial inoculum is not clearly understood. This study determined the potential for urediniospore survival overwinter. Uredia-bearing bean leaves from artificially inoculated greenhouse-grown plants were kept outside near a field from November to May from 1990 to 1996. Based on bioassays urediniospores survived overwinter, but viability declined over time. Overwinter survival indicates urediniospores may function as initial inoculum.
First Report of Tomato chlorosis virus in Puerto Rico
Authors: Wintermantel W. M. , Polston J. E. , Escudero J. , Paoli E. R.
Published: May 2007

Symptoms of interveinal chlorosis, necrotic flecking, thickening, and rolling of leaves were observed on leaves of field-grown tomato (Lycopersicon esculentum) plants in Jauna Diaz, Puerto Rico. These symptoms are indicative of those produced by the whitefly-transmitted criniviruses, Tomato infectious chlorosis virus (TICV) and Tomato chlorosis virus (ToCV) (1). Samples collected from two symptomatic plants were examined by leaf dip and were found to contain long flexuous rods approximately 800 nm in length, characteristic of criniviruses. Symptomatic leaves were used for extraction of total nucleic acid and for whitefly transmission studies. The greenhouse whitefly, Trialeurodes vaporariorum (Westwood), is a highly efficient vector of TICV, but an inefficient vector of ToCV, whereas the banded wing whitefly, T. abutilonea (Haldeman), is an efficient vector of ToCV but does not transmit TICV (2). Whiteflies of both species were allowed to feed separately on symptomatic tomato leaves for 24 h and then transferred to healthy Physalis wrightii and Nicotiana benthamiana indicator plants. Symptoms characteristic of ToCV infection developed on 3 of 3 P. wrightii plants and 2 of 3 N. benthamiana plants following transmission by T. abutilonea. Only 1 of 3 P. wrightii plants developed such symptoms following transmission by T. vaporariorum, while no N. benthamiana plants developed symptoms, suggesting that the virus responsible for the tomato disease was ToCV. Dot blot hybridizations were performed on total nucleic acids extracted from 0.1 g of symptomatic leaves of field samples using probes specific for TICV or ToCV (2), as well as probes specific for four additional criniviruses. Symptomatic and asymptomatic leaves of plants in transmission tests, as well as comparable leaves from control plants, were also tested by dot blot. Although no criniviruses could be detected by dot blot in the original tomato tissue, these hybridizations identified ToCV in all symptomatic plants from the transmission experiments, confirming the presence of ToCV in Puerto Rico. No additional criniviruses were detected in any samples, and negative controls were virus-free. This is the first time a tomato crinivirus has been detected in the Caribbean, outside of the continental United States. The ability of ToCV to be transmitted by four different whitefly species increases the potential for this virus to spread throughout the Caribbean Basin.

References: (1) G. C. Wisler et al. Plant Dis. 82:270, 1998. (2) G. C. Wisler et al. Phytopathology 88:402, 1998.
Detection of Sorghum yellow banding virus Infecting Grain Sorghum in Venezuela
Authors: Garrido M. J. , Trujillo G. E. , Cuello R.
Published: May 2007

Naturally infected grain sorghum plants (Sorghum bicolor) in Maracay, Aragua State, showed yellow speckles, streaks and bands with chlorosis, stunting, and necrosis. A virus was mechanically transmitted to 3 to 10% of inoculated sorghum cvs. Atlas and Himeca-303 plants in the greenhouse. They developed symptoms similar to those in the field within 20 days after inoculation. The virus infected a narrow range of the gramineous species. It was not transmitted by Rhopalosiphum maidis, Schizaphis graminum, Peregrinus maidis, Dalbulus maidis, nor Hortensia similis, nor by sorghum seed. The virus was purified three times from fresh infected tissue giving yields as high as 14.7 mg/100 g. The A260/ A280 was 1.55. The virions were isometric, 25 nm in diameter, and contained a single capsid protein with a molecular weight of approximately 29 kDa. The virus was highly stable in sap. The virus was not serologically related to eight small isometric viruses that infect Gramineae species but did react in agar double-diffusion tests with antiserum (supplied by R. W. Toler) to Sorghum yellow banding virus (SYBV), a virus that affects sorghum and sorghum × sudangrass hybrids in Texas and California (1). Based on the above characteristics, the virus is considered to be SYBV. This disease has not been found in other states in Venezuela. This is the first report of SYBV infecting grain sorghum in Venezuela.

Reference: (1) V. A. Klaassen and B. W. Falk. Phytopathology 79:646, 1989.
Outbreak of Brown Spot of Tobacco Caused by Alternaria alternata in Connecticut and Massachusetts
Authors: LaMondia J. A.
Published: May 2007

In early August 2000, a leaf spot disease of broadleaf tobacco (Nicotiana tabacum L.) was widespread and severe in Connecticut and Massachusetts. The spots were roughly circular, with necrotic centers and concentric rings and often surrounded by a yellow halo. Spots ranged in size from small fleck symptoms (approximately 1 mm) to large lesions 1 to 3 cm in diameter. The putative tobacco brown spot pathogen, Alternaria alternata (Fr.:Fr.) Keissl., was isolated on potato-dextrose agar from symptomatic tissues after surface-sterilization for 30 s in 0.525% NaOCl. Brown conidia were produced in culture, often in chains. Conidia were variable in size, but tapered to a lighter colored short beak that was usually less than one quarter the length of the conidia (1). Healthy, detached broadleaf leaves (the first fully expanded leaves) were inoculated with 25 drops (45:1 each) of water alone or water containing 5.0 × 104 conidia combined from ten cultures (four leaves for each treatment). Drops were placed in the area between veins and allowed to air-dry for 3 h. Leaves were then misted and placed in a plastic bag in a growth chamber maintained at 24°C with 8 h light per day. Brown spot symptoms developed in 25% of the inoculated spots but not in areas of water controls after 11 days. Symptomatic tissue was surface-sterilized and A. alternata was consistently reisolated on potato-dextrose agar. Brown spot commonly occurs in the Connecticut River Valley on senescent leaves near the soil; however, in August 2000, symptoms were present on leaves of all ages. The greatly increased incidence and severity of brown spot were likely due to unusually wet conditions during the 2000 cropping season (2). In Windsor, CT, an average of 3 days per week of rain was recorded throughout the growing season. Brown spot symptoms render broadleaf tobacco leaves unsuitable for use as a natural leaf cigar wrapper and result in a complete loss of value. Data released by the New England National Agricultural Statistics Service on 1 September 2000 indicated that broadleaf tobacco losses in Connecticut and Massachusetts were at least 75 and 89% of the total acreage, respectively.

References: (1) G. B. Lucas. Tob. Sci. 15:37,1971. (2) J. R. Stavely and C. E. Main. Phytopathology 60:1591, 1970.
First Report of Tomato yellow leaf curl virus in Louisiana
Authors: Valverde R. A. , Lotrakul P. , Landry A. D. , Boudreaux J. E.
Published: May 2007

Tomato yellow leaf curl virus (TYLCV) is a begomovirus (Geminiviridae) that causes a serious disease of tomato throughout the world. In 1997, the strain from Israel of TYLCV (TYLCV-IS) was found infecting tomatoes in Florida for the first time in the United States (1). During late spring of 2000, approximately 90% of the tomato plants (Lycopersicon esculentum) in a farm near New Orleans exhibited severe stunting, leaf cupping, and chlorosis. Symptoms were similar to those caused by TYLCV. Whiteflies (Bemisia tabaci biotype B) were present in the field but in relatively low numbers. The effect on yield reduction varied from negligible (late infections) to 100% (early infections). Six selected plants showing symptoms were assayed by polymerase chain reaction (PCR) using begomovirus-specific primers. Capsicum frutescens infected with an isolate of Texas pepper virus from Costa Rica was used as positive control. DNA was extracted using Plant DNAzol Reagent (GIBCO BRL). PCR was conducted using degenerate primers AV494/AC1048 that amplify the core coat protein region of most begomoviruses (2). PCR yielded a DNA fragment of approximately 550 bp, suggesting that a begomovirus was associated with the disease. The amplified DNA of one field isolate was cloned and the nucleotide (nt) sequence determined. Sequence comparisons with other begomoviruses in the GenBank Database indicated that the Louisiana isolate shared 100% nt identity with TYLCV-IS (GenBank Accession X76319). Successful transmission (100%) to Bonny Best tomato were obtained with four groups of 10 whiteflies each (B. tabaci biotype B) that fed on TYLCV-IS infected tomato plants. Acquisition and transmission feedings were for 2 days. In all cases, the virus was diagnosed by the ability to reproduce typical TYLCV-like symptoms in tomato and PCR. The virus was also successfully graft-transmitted to tomato cv. Bonny Best, Nicotiana benthamiana, and tomatillo (Physalis ixocarpa) using scions from tomato plants infected with a whitefly transmitted virus isolate. This is the first report of TYLCV-IS in Louisiana.

References: (1) J. E. Polston et al. Plant Dis. 83:984–988, 1999. (2) S. D. Wyatt and J. K. Brown. Phytopathology 86:1288–1293, 1996.
Catharanthus roseus, an Experimental Host Plant for the Citrus Strain of Xylella fastidiosa
Authors: Monteiro P. B. , Renaudin J. , Jagoueix-Eveillard S. , Ayres A. J. , Garnier M. , Bové J. M.
Published: May 2007

We verified by pathogenicity tests that the herbaceous plant Catharanthus roseus (Madagascar periwinkle) can be used as an experimental host for the strain of Xylella fastidiosa that causes citrus variegated chlorosis (CVC). Plants were mechanically inoculated with CVC strain 9a5c, the genome of which was recently sequenced. Plants were inoculated with the virulent 8th passage (9a5c-8) and the 51st passage (9a5c-51). Leaf deformation and stunting were seen 2 months after inoculation on 18 of 21 plants with 9a5c-8 and 8 of 21 plants with 9a5c-51. The plants were infected with X. fastidiosa as shown by polymerase chain reaction. The bacterium could be reisolated from all plants tested, showing that CVC-X. fastidiosa multiplied and moved systemically in C. roseus plants causing dysfunction in plant growth. The disease symptoms evolved within 4 months post-inoculation to a severe leaf chlorosis in all inoculated plants. The localization of X. fastidiosa in the xylem was verified by immunofluorescence. Genes coding for proteins with homologies to plant sterol-C-methyltransferase, a transketolase-like protein, subunit III of photosystem I, and a desiccation protectant protein were found to be differentially expressed in symptomatic C. roseus plants as a response to infection with X. fastidiosa in comparison to healthy plants. A tentative correlation between the pattern of expression of these C. roseus genes with the mechanism of pathogenicity of X. fastidiosa is discussed.
Host-Parasite Relationships in Root-Knot Disease of White Mulberry
Authors: Castillo P. , Di Vito M. , Vovlas N. , Jiménez-Díaz R. M.
Published: May 2007

Severe infections of white mulberry feeder roots and heavy soil infestations by Meloidogyne arenaria race 2 were found in southern Spain. This is the first record of M. arenaria on white mulberry in Europe. Morphometric observations, analysis of the esterase electrophoretic pattern, and artificial inoculations of race differentials were used to characterize nematodes. Nematode-induced mature galls were spherical and usually contained one or more females, males, and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. Giant cell cytoplasm was aggregated along a thickened cell wall. Vascular tissues within galls appeared disorganized. The relationship between the initial nematode population density (Pi) in a series from 0 to 1,024 eggs and juveniles/cm3 soil and growth of white mulberry seedlings was tested in the greenhouse. A Seinhorst model was fitted to plant height and top fresh weight. Tolerance limits of white mulberry to M. arenaria race 2 for plant height and top fresh weight were, respectively, 1.1 and 1.38 eggs and juveniles/cm3 soil. The minimum relative values for plant height and top fresh weight were 0 at Pi ≥ 64 and Pi ≥ 128 eggs and juveniles/cm3 soil, respectively. Maximum nematode reproduction rate was 435-fold at the lowest Pi.
Characterization of South African Isolates of Phytophthora infestans
Authors: McLeod A. , Denman S. , Sadie A. , Denner F. D. N.
Published: May 2007

Severe late blight epidemics in South Africa in 1995 and 1996 prompted an investigation into the mating type, genotype, and metalaxyl sensitivity of populations of Phytophthora infestans. A country-wide survey was conducted from 1996 to 1998 in which isolates were collected from 101 potato fields (656 isolates) and 16 tomato fields (57 isolates). Six hundred and fifty-seven isolates (600 potato and 57 tomato) were analyzed for mating type, while subsets of isolates were analyzed for genotype at the Glucose-6-phosphate isomerase locus (n = 148), DNA fingerprinting with probe RG-57 (n = 61) and mitochondrial DNA haplotype (n = 20). All isolates tested had the characteristics typical of the pre-1980 population (A1 mating type, 86/100 Gpi genotype, US-1 fingerprint pattern, and mtDNA haplotype I-b) previously found worldwide. Metalaxyl sensitivity testing of 656 potato isolates by the in vitro leaf disk method showed that the frequency of highly resistant isolates (50% effective concentration [EC50] > 200 μg a.i./ml) in potato production regions increased from 35% in 1996 to 51% in 1997. The high frequency of resistant isolates was confined to the southern coastal regions in 1996 and 1997, as well as the western Free State in 1997. Although phenylamides were withdrawn from the southern coastal region in December 1996, screening tests carried out in 1998 indicated that resistance levels remained high (≥83%). Sensitive isolates (EC50 < 40 μg a.i./ml) predominated in the remaining six potato production regions. Screening of 45 isolates collected from tomatoes indicated that no resistant strains were present in the sample tested.
First Report of Cucumber vein yellowing virus in Spain
Authors: Cuadrado I. M. , Janssen D. , Velasco L. , Ruiz L. , Segundo E.
Published: May 2007

In the autumn of 2000, an outbreak of a disease caused considerable losses in greenhouse cucumber crops in Almeria (Spain). Infected plants showed vein clearing followed by chlorosis in leaves and yellow/green chlorotic spots on fruits. These symptoms as well as the presence of Bemisia tabaci in the crops suggested the possible involvement of Cucumber vein yellowing virus (CVYV), a proposed member of the Potiviridae family, which was first described in 1960 in Cucumis spp. from Israel (1). B. tabaci populations and leaves from cucumber plants were collected from the greenhouses and analyzed by RT-PCR using specific primers (CV(+): 5′-AGCTAGCGCGTATGGGGTGAC-3′; CV(-): 5′-GCGCCGCAAGTGCAA-ATAAAT-3′) that we designed based on the partial sequence published for CVYV (2). Total nucleic acid extracts from both B. tabaci individuals and the collected plants yielded amplification products of the expected size (449 bp), which were cloned and sequenced (Genebank accession number AJ301640). The sequence was 95.6% identical to that previously reported for CVYV. Nonviruliferous B. tabaci whiteflies were given a 24-h acquisition period on symptomatic leaves and then placed in groups of 15 insects on each of 10 healthy cucumber plants at the 4 leaf-stage for a 24-h inoculation period. Inoculated and control plants were analyzed 1 week later and the infection with CVYV was confirmed (10/10) by RT-PCR. Doublestranded RNA extractions from field-collected samples and from plants inoculated under controlled conditions suggested that no dsRNA formation was associated with the infection. This is the first report of CVYV in Spain.

References: (1) S. Cohen and F. E. Nitzany. Phytopathol. Medit. 1:44, 1960. (2) H. Lecoq et al. J. Gen. Virol. 81:2289, 2000.
Evaluation of Continuous Application Technology for Delivery of the Biocontrol AgentPseudomonas putida06909-rif/nal
Authors: Steddom K. , Menge J. A.
Published: May 2007

We evaluated a commercial field fermentor as a means of culturing and delivering a bacterial biocontrol agent, Pseudomonas putida 06909-rif/nal, through irrigation water. There was no evidence of contamination in 12-hour cultures produced by the fermentor. It produced 120 liters of inoculum at 5 × 108CFU/ml after 12-hour fermentations, allowing two applications per day. Dilutions up to 1:100,000 of inoculum of P. putida 06909-rif/nal produced by the fermentor allowed the biocontrol agent to effectively colonize soil in greenhouse trials. Bacteria produced in 19-hour fermentations colonized soil better than bacteria produced in 12-hour fermentations. Ten repetitive applications of P. putida 06909-rif/nal yielded soil population levels similar to those from a single application at 10-fold greater concentrations. Repetitive applications of lower concentrations may be a cost-effective method for delivering bacterial biocontrol agents to large acreages. This work suggests that the commercial field fermentor would be a viable instrument for delivering bacterial biocontrol agents for commercial-scale field applications.
Management of Black Spot of Rose with Winter Fungicide Treatment
Authors: Bowen K. L. , Roark R. S.
Published: May 2007

Fungicides were evaluated for their efficacy against black spot of rose, caused by Diplocarpon rosae, when applied during winter months to hybrid tea rose plants in two studies. One study, conducted at two Auburn University campus sites, consisted of applications of horticultural oil, chlorothalonil plus an antitranspirant, and cyproconazole, along with nontreated plants; one site included triforine applications. Rose canes were treated two and three times between late October and February in 1996-97 and 1997-98, respectively; then plants were examined every 2 to 4 days beginning in mid-February for onset of symptoms of black spot. In both years, winter applications of fungicides (chlorothalonil, cyproconazole, and triforine) delayed disease onset compared with treatments without fungicides (nontreated and oil applications). Decreased plant defoliation, as well as improved plant vigor, were observed through the 1998 growing season following fungicidal winter treatments at campus sites; winter treatments with oil did not suppress disease compared with no treatment. In a second study started in November 1997, at a site near Shorter, AL, three systemic fungicides (myclobutanil, cyproconazole, and triforine) were applied to rose canes during the winter; nontreated plants were included. Decreased disease symptoms and defoliation of rose plants were observed early in the 1998 and 1999 seasons following winter applications of cyproconazole and triforine compared with myclobutanil or nontreated plants. Winter treatments with these fungicides did not consistently provide season-long reduction of black spot. However, season-long plant vigor and flower production on plants were improved at the Shorter site following winter applications of any of the above systemic fungicides compared with nontreated plants.
Xanthomonas Blight of Onion in South Africa
Authors: Serfontein J. J.
Published: May 2007

During April 1999, a foliar blight of onion (Allium cepa L. ‘Granex 33’) was reported in an early commercial planting under center pivot irrigation in the Limpopo Valley of the Northern Province of South Africa. Regular fungicide sprays failed to inhibit the progress of the disease. Foliar symptoms started as water-soaked lesions that elongated and turned chlorotic followed by tissue collapse in some leaves. Leaves often collapsed at the point of infection. Bulb size was severely reduced and premature leaf death caused irregular maturation and bulb size in the field. The symptoms were similar to those of Xanthomonas blight, described on the same cultivar in Hawaii (1). Microscopic examination of hand cut sections trough lesion margins showed bacterial streaming. Isolation on semi-selective diagnostic milk Tween agar (2) yielded almost pure cultures of a typical xanthomonad. The mucoid, yellow pigmented bacterium was rod shaped, gram negative, catalase positive, oxidase negative, utilized glucose oxidatively, and was lypolytic (Tween 80), proteolytic (skimmed milk), and amolytic. Biolog GN Microplate profiles as read by the MicroLog database release 3.50 (Biolog, Hayward, CA) were similar to those of a pathovar (similarity indices of 0.29 to 0.71). Symptoms were successfully reproduced on glasshouse grown Granex 33 seedlings at the five-leaf stage by spray and syringe inoculations (1) and the pathogen reisolated as described above. Ten seedlings were used in the pathogenicity test, of which five served as controls. After inoculation, seedlings were covered overnight with plastic bags, after which bags were removed and seedlings grown in the greenhouse at 24 to 30°C and natural light until symptom development. Attempts to isolate the pathogen from the seed lot used to plant the affected field were unsuccessful. The disease re-occurred in early plantings of Granex 33 on the same farm in April 2000 toward the end of an unusually wet summer rainy season. Damage caused by the disease was so severe in one early planting that it was plowed under. High temperatures and humid conditions combined with overhead irrigation could have enhanced disease development and spread during the early growth of the crop. No further spread was observed during cooler and drier weather later in the season.

References: (1) A. M. Alvarez et al. Phytopathology 68:1132, 1978. (2) T. Goszczynska and J. J. Serfontein. J. Microbiol. Methods 32:65, 1998.
First Report of Columbia Root Knot Nematode (Meloidogyne chitwoodi) in Potato in Texas
Authors: Szalanski A. L. , Mullin P. G. , Harris T. S. , Powers T. O.
Published: May 2007

Columbia root-knot nematode, Meloidogyne chitwoodi Golden et al. (1) was identified from potatoes, Solanum tuberosum L., collected from Dallam County, Texas in October 2000. Seed potatoes are the most likely source for this introduction. This nematode is currently found infecting potatoes grown in California, Colorado, Idaho, New Mexico, Nevada, Oregon, Utah, and Washington. Some countries prohibit import of both seed and table stock potatoes originating in states known to harbor M. chitwoodi. Lesions on the potatoes had discrete brown coloration with white central spots in the outer 1 cm of the tuber flesh. Female nematode densities averaged 3 per square centimeter of a potato section beneath the lesions. Nematodes were morphologically identified as M. chitwoodi based on the perineal pattern of mature females and the tail shape of juveniles per Golden et al. (1). Using polymerase chain reaction-RFLP of the rDNA ITS1 region and the mtDNA COII-16S rRNA region (2), individual juveniles were identified as M. chitwoodi based on their restriction fragment patterns. This is the first report of Columbia root-knot nematode infecting potatoes in Texas. The distribution of this nematode in potato fields throughout central United States should be determined.

References: (1) A. N. Golden et al. J. Nematol. 12:319, 1980. (2) T. O. Powers and T. S. Harris. J. Nematol. 25:1, 1993.