First Report of Xanthomonas fragariae Causing Angular Leaf Spot on Strawberry Plants in México.

The state of Michoacán is the most important strawberry producer in México. During January 2007, field-grown strawberry plants cv. Aromas showing vein necrosis were observed in 3 ha in Zamora County, in fruit production fields. The average disease incidence in the field was 80%. Infected plants presented water-soaked lesions limited by veins on the lower leaf surfaces, which enlarged to form angular spots (1). Additionally, most affected plants presented severe necrosis in the main veins and reddish to necrotic lesions on the upper leaf surfaces. Gram-negative bacteria were consistently isolated from leaves with water-soaked lesions. Isolated bacteria produced mucoid, yellow colonies on YDC, grew on tween and nutrient agar (NA), but not on SX media. Strains produced non-fluorescent colonies on King's B media, were positive starch hydrolysis, negative esculin hydrolysis; and produced acid from fructose but not from arabinose, galactose, celobiose, and trehalose. Growth was inhibited by 2% NaCl (3). Indirect ELISA analysis (NEOGEN, Lansing, MI) was conducted using antibodies specific for Xanthomonas fragariae. Conventional PCR assay using the primer pairs 241A/241B was performed (2). The ELISA test was positive. The expected 300- and 550-bp bands were observed in the PCR analysis. The bacteria was identified as X. fragariae Kennedy and King. Pathogenicity tests were conducted twice in a greenhouse (24 ± 4°C) on a total of five strawberry cv. Aromas plants. The main vein of each of three leaves per plant were punctured using sterile needles. Pathogen inoculum was obtained from 6- to 8-day-old NA cultures. Bacteria were applied onto the wounds with a sterile cotton swab dipped into the bacterial suspension (105 CFU/ml). Inoculated plants were covered with plastic bags for 48 h. Symptoms resembling those seen in the field developed on all inoculated plants after 9 days. X. fragariae was re-isolated from the necrotic lesions and identified by PCR. Control plants were similarly inoculated with water but did not develop symptoms. To our knowledge, this is the first report of X. fragariae causing angular leaf spot in strawberry in Michoacán, México. References: (1) J. L. Maas, ed. Compendium of Strawberry Diseases. The American Phytopathological Society, St. Paul, MN, 1998. (2) M. R. Pooler et al. Appl. Environ. Microbiol. 62:3121, 1996. (3) N. W. Schaad et al. Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001.

First Report of Mango Malformation Disease Caused by Fusarium pseudocircinatum in Mexico.

Mango (Mangifera indica L.) malformation disease (MMD) is one of the most important diseases affecting this crop worldwide, causing severe economic loss due to reduction of yield. After the first report in India in 1891 (3), MMD has spread worldwide to most mango-growing regions. Several species of Fusarium cause the disease, including F. mangiferae in India, Israel, the USA (Florida), Egypt, South Africa, Oman, and elsewhere; F. sterilihyphosum in South Africa and Brazil; F. proliferatum in China; F. mexicanum in Mexico; and recently, F. tupiense in Brazil (1,2,3,4). Besides F. mexicanum, F. pseudocircinatum, not yet reported as a causal agent of MMD, was isolated in Mexico from affected inflorescences and vegetative malformed tissues (4). Symptoms of vegetative malformation caused by F. pseudocircinatum included hypertrophied, tightly bunched young shoots, with swollen apical and lateral buds producing misshapen terminals with shortened internodes and dwarfed leaves. Infected inflorescences of primary or secondary axes on affected panicles were shortened, thickened, and highly branched, while the peduncles became thick, remained green and fleshy, and branches profusely resembled a cauliflower in shape and size (3). Ten isolates of F. pseudocircinatum were recovered from cultivars Ataulfo, Criollo, Haden, and Tommy Atkins in Guerrero, Campeche, and Chiapas states and characterized. Isolates produced mostly 0-septate but occasionally 1- to 3-septate oval, obovoid, or elliptical aerial conidia (0-septate: 4 to 19 [avg. 8.7] × 1.5 to 4 [avg. 2.6] µm) in false heads in the dark and in short false chains under black light, unbranched or sympodially branched prostrate aerial conidiophores producing mono- and polyphialides, and sporodochia with straight or falcate conidia that were mostly 3- to 5-septate, but sometimes up to 7-septate (3-septate: 25 to 58 [avg. 41] × 2 to 3.3 [avg. 2.9] µm; 5-septate: 33.5 to 76.5 [avg. 56.7] × 2.5 to 6 [avg. 3.5] µm). Circinate sterile hyphae were rarely formed. Two representative isolates, NRRL 53570 and 53573, were subjected to multilocus molecular phylogenetic analyses of portions of five genes: nuclear large subunit 28S ribosomal RNA, ß-tubulin, calmodulin, histone H3, and translation elongation factor (TEF)-1α (GenBank GU737456, GU737457, GU737290, GU737291, GU737371, GU737372, GU737425, GU737426, GU737398, and GU737399). Two pathogenicity tests were conducted with NRRL 53570 and 53573 on healthy 2-year-old nucellar seedlings of polyembryonic Criollo; 20 µl conidial suspensions (5 × 106 conidia/ml) of each isolate and water controls were inoculated separately on 15 buds on 3 different trees, as described previously (1). The following conditions were used in experiment 1: 24 to 27°C with light intensity of 16.2 to 19.8 •Mol m-2s-1 in the range of 400 to 700 nm, and photoperiods of 14 h light and 10 h dark. Typical vegetative disease symptoms were discernible in plants inoculated with NRRL 53570 (20%) and 53573 (7%) after 8 months. In experiment 2, after 3 months growth under the above conditions, seedlings were transferred to an outdoor nursery in Iguala, Guerrero. Typical vegetative symptoms of MMD were observed in 86.7 and 13.3% of the buds inoculated with F. pseudocircinatum NRRL 53570 and 53573, respectively, after 9 months. Isolates from typical symptomatic vegetative buds were confirmed as F. pseudocircinatum by sequencing a portion of their TEF-1α gene, thus fulfilling Koch's postulates. This is the first report of F. pseudocircinatum as a causal agent of MMD. References: (1) S. Freeman et al. Phytopathology 89:456, 1999. (2) C. S. Lima et al. Mycologia 104:1408, 2012. (3) W. F. O. Marasas et al. Phytopathology 96:667, 2006. (4) G. Otero-Colina et al. Phytopathology 100:1176, 2010.

First Report of Geranium Rust (Puccinia pelargonii-zonalis) in the State of Michoacán, México.

Geranium is one of the most popular ornamental plants in México. In December 2012, rust symptoms were observed on leaves of common geranium (Pelargonium × hortorum L. H. Bailey) growing in pots in garden landscapes in Morelia, Michoacán. Dark brown pustules with chlorotic halos appeared on the lower leaf surface. A center pustule surrounded by one or more partial-to-complete concentric circles of smaller pustules was observed in each lesion. Urediniospores were globose or subglobose to ovoid, light brown, echinulated, thin-walled with two more or less conspicuous subequatorial pores, and 21 to 29 × 18 to 24 µm (25.5 × 22.8 µm average). Teliospores were not observed. Based on these characters, the rust was identified as Puccinia pelargonii-zonalis Doidge (1,2). Pathogenicity tests were conducted on three healthy P. × hortorum plants that were sprayed with water droplets containing urediniospores. The inoculated plants were covered with a plastic bag and placed in a screened house. The bags were removed after 24 h. Afterwards, the plants were maintained outside the screened house in full sun at ambient temperature (24 to 30°C in the day and 5 to 10°C at night). Initial symptoms were observed 15 to 17 days post inoculation. Symptoms appeared as small light yellow spots on the upper surface of mature leaves. Urediniospores production on the lower surface of the leaves was evident 22 to 25 days post inoculation. To our knowledge, this is the first report of P. pelargonii-zonalis in the state of Michoacán, México. Geranium rust has been previously reported only in the state of Guanajuato (2). References: (1) E. M. Doidge. Bothalia 2:1, 1926. (2) H. L. Gallegos and G. B. Cummings. Uredinales (royas) de México. Vol. 1. Culiacán, Sinaloa, México, SARH, 1981.

First Look Into the Ambrosia Beetle-Fungus Symbiosis Present in Commercial Avocado Orchards in Michoacán, Mexico.

Most beetle-fungus symbioses do not represent a threat to agricultural and natural ecosystems; however, a few beetles are able to inoculate healthy hosts with disease-causing fungal symbionts. Here, we report the putative nutritional symbionts associated with five native species of ambrosia beetles colonizing commercial avocado trees in four locations in Michoacán. Knowing which beetles are present in the commercial orchards and the surrounding areas, as well as their fungal associates, is imperative for developing a realistic risk assessment and an effective monitoring system that allows for timely management actions. Phylogenetic analysis revealed five potentially new, previously undescribed species of Raffaelea, and three known species (R. arxi, R. brunnea, R. fusca). The genus Raffaelea was recovered from all the beetle species and across the different locations. Raffaelea lauricola (RL), which causes a deadly vascular fungal disease known as laurel wilt (LW) in Lauraceae species, including avocado, was not recovered. This study points to the imminent danger of native ambrosia beetles spreading RL if the pathogen is introduced to Mexico's avocado orchards or natural areas given that these beetles are associated with Raffaelea species and that lateral transfer of RL among ambrosia beetles in Florida suggests that the likelihood of this phenomenon increases when partners are phylogenetically close. Therefore, this study provides important information about the potential vectors of RL in Mexico and other avocado producing regions. Confirming beetle-fungal identities in these areas is especially important given the serious threat laurel wilt disease represents to the avocado industry in Mexico.

First Report of Powdery Mildew on Carrot Caused by Erysiphe heraclei in Michoacan, Mexico.

Carrot (Daucus carota L. subsp. sativus (Hoffm.) Arcang.) is planted as a home-grown vegetable in the central region of Michoacan, Mexico. Powdery mildew was observed on carrot plants cv. Nantesa at several locations near Morelia, Michoacan during March 2009. Affected plants had abundant, white, superficial conidia and mycelium on leaves and stems. All plants at each of five locations surveyed had powdery mildew symptoms with percent foliage coverage ranging from 50 to 80%. Mycelial growth was amphigenous, mainly on the upper leaf surface, covering the whole leaf and with irregular patches on inflorescences and stems. Hyphae were ectophytic with lobed appressoria. Conidiophores presented foot cells 22.5 to 35 (30) × 5.75 to 7 (6.3) µm followed by two cells, one shorter and one longer than the foot cell. Conidia were produced singly, most subcylindric to cylindric, lacked fibrosin bodies, and measured 31.2 to 42 (36.2) × 8.7 to 11.2 (10.5) µm. The teleomorph was not observed. Genomic DNA was extracted from infected leaves; sequences of the internal transcribed spacers (ITS) inclusive of 5.8S rDNA were amplified using previously described primers specific for Erysiphales (3). The ITS sequences shared 100% homology to Erysiphe heraclei specimen VPRI41227 from carrot in Australia (GenBank Accession No. EU371725). On the basis of the morphological characteristics observed and the ITS rDNA sequences, the pathogen was identified as E. heraclei DC. The ITS sequence was deposited in NCBI as Accession No. GU252368. Pathogenicity tests were conducted twice on a total of 10 healthy 8-week-old carrot plants cv. Nantesa. Infected plants were placed in close proximity to healthy plants and maintained in a greenhouse at 27 ± 5°C. Initial signs and symptoms were observed 3 weeks after inoculation and appeared as small, white colonies, which later coalesced and covered most of the foliage. Microscopic examination of the conidia and mycelial morphology matched the originally described pathogen, E. heraclei. Powdery mildew caused by this pathogen has been extensively reported on diverse species and genera of the Apiaceae in Europe and remains one of the most important diseases of carrot (2). The appearance of E. heraclei in diverse regions on a variety of umbelliferous crops indicates that formae speciales have spread, infecting different and specific hosts (1-3). Recently, E. heraclei has been reported on parsley in Puebla, Mexico (4). To our knowledge, this is the first report of E. heraclei causing powdery mildew on carrot in Michoacan, Mexico. This pathogen should be considered as a threat to commercial carrot crops in Mexico. Other crops in the Apiaceae may not be at risk in this area if this powdery mildew is specific for carrots. References: (1) B. J. Aegerter. Page 22 in: Compendium of Umbelliferous Crop Diseases. The American Phytopathological Society, St. Paul, MN, 2002. (2) U. Braun. The Powdery Mildew (Erysiphales) of Europe. Gustav Fischer-Verlag. Jena, Germany, 1995. (3) J. H. Cunnington et al. Australas. Plant Pathol. 32:421, 2003. (4) M. J. Yáñez-Morales et al. Schlechtendalia 19:47, 2009.

Root Rot of Hydroponically Grown Lettuce Caused by Phytophthora drechsleri in Mexico.

During March of 2008, bibb lettuce (Lactuca sativa L.) plants with severe wilting and root rot were observed in a commercial liquid-hydroponic greenhouse in Guanajuato, Mexico. By July of that year, the disease affected most plants in the facility. A Phytophthora sp. was consistently isolated from diseased roots on potato carrot agar. Several Phytophthora isolates were morphologically characterized. Sporulation was achieved by placing colonized disks of clarified V8 juice agar (V8A) into nonautoclaved soil extract (10 g avocado soil/1,000 ml distilled water, stirred for 3 h, and filtered). Sporangia were persistent, nonpapillate, and 40 to 58 µm long × 30 to 40 µm wide. External and internal proliferation was observed. Hyphal swellings were predominantly rounded. Oospores were not observed. The isolates grew on V8A at 35°C. Pathogenicity tests were conducted twice by utilizing a representative isolate (AC1) on bibb lettuce seedlings (10 replicates per experiment). Seeds were placed on sterile, water-soaked paper in petri dishes. After 10 days, each lettuce seedling was placed into a tube containing approximately 2 ml of sterile distilled water and 2,000 zoospores. Control plants were placed in tubes with water only. Plants were incubated for 7 days in a moist chamber at 25°C. Symptoms of wilting and root necrosis were observed 2 to 3 days after inoculation. All plants were dead 5 to 7 days after inoculation. A Phytophthora sp. was always isolated from the roots of inoculated plants. Control plants remained healthy. The pathogen was identified as Phytophthora drechsleri Tucker according to morphological characteristics. To confirm the identity of the pathogen, sequences of the internal transcribed spacers (ITS) were obtained from three representative isolates. The ITS sequences that were obtained shared 100% homology to several strains of P. dreschleri, including isolates from cucurbits (GenBank Accession No. AF228097). The ITS sequence was deposited in NCBI as Accession No. FJ790770. P. cryptogea and P. dreschleri have been reported as causing root rot on lettuce grown hydroponically in the United States and Korea (1,2). To our knowledge, this is the first report of P. drechsleri causing root rot on lettuce in Mexico. References: (1) H. J. Jee et al. Plant Pathol. J. 17:311, 2001. (2) A. R. Linde et al. Plant Dis. 74:1037, 1990.

Congenital colonic stenosis: a case of late-onset.

PURPOSE: Colonic atresia and stenosis are rare causes of intestinal obstruction in the infant. Only 1.8%-15% of intestinal atresias occur in the colon. Congenital colonic stenosis is even less common than colonic atresia. Only 10 cases have been reported in Literature since 1966 and only one late-onset case has been reported in Literature until now. We describe the case of a 4-month-old baby coming to our attention because of an intestinal subocclusion due to a congenital colonic stenosis of the ascending colon. CASE REPORT: A 4-month-old baby came to our attention for persistent abdominal distension, reduction of bowl function and decaying of overall clinical conditions. A plain abdominal radiograph showed distended intestinal loops with air-fluid levels and no gas in the rectum. During the barium enema the contrast medium appeared to completely fill the lumen of the colon up to the ileo-cecal valve and Cecum appearing higher than normal. Beyond the ileo-cecal valve, the contrast medium showed an abnormal hypotonic dilatation of the small intestinal loops. Suspecting an organic intestinal obstruction, an explorative laparotomy was deemed necessary and at halfway in the ascending colon a stenosis was found. RESULTS: The post-operative course was uneventful and the patient is currently in good clinical conditions, has a normal diet and is thriving. CONCLUSION: Considering both the Literature and our own experience, it is wise to reckon the congenital colonic stenosis as a rare but possible cause of complete or partial intestinal obstruction not only in the newborn but also throughout the first year of life.

A Novel Disease of Big-Leaf Mahogany Caused by Two Fusarium Species in Mexico.

Big-leaf mahogany (Swietenia macrophylla) is valued for its high-quality wood and use in urban landscapes in Mexico. During surveys of mango-producing areas in the central western region of Mexico, symptoms of malformation, the most important disease of mango in the area, were observed on big-leaf mahogany trees. The objectives of this research were to describe this new disease and determine its cause. Symptoms on big-leaf mahogany at four sites in Michoacán, Mexico resembled those of the vegetative phase of mango malformation, including compact, bunched growth of apical and lateral buds, with greatly shortened internodes and small leaves that curved back toward the supporting stem. Of 163 isolates that were recovered from symptomatic tissues, most were identified as Fusarium pseudocircinatum (n = 121) and F. mexicanum (n = 39) using molecular systematic data; two isolates represented unnamed phylospecies within the F. incarnatum-equiseti species complex (FIESC 20-d and FIESC 37-a) and another was in the F. solani species complex (FSSC 25-m). However, only F. mexicanum and F. pseudocircinatum induced malformation symptoms on 14-day-old seedlings of big-leaf mahogany. The results indicate that F. mexicanum and F. pseudocircinatum, previously reported in Mexico as causal agents of mango malformation disease, also affect big-leaf mahogany. This is the first report of this new disease and the first time that F. mexicanum was shown to affect a host other than mango.

First Report of Powdery Mildew on Greenhouse Tomatoes Caused by Oidium neolycopersici in Michoacan, Mexico.

During June and July of 2007, powdery mildew-infected tomato (Lycopersicum esculentum Mill. cv. Reserve) plants were observed in a commercial greenhouse with an open hydroponic system in Morelia County. Disease incidence increased from 0.5% to more than 90% in 1 month. Infected plants showed leaves with irregular areas of dense, white mycelium covering most of the upper surface. Microscopic analysis showed hyaline, septate hyphae with lobed appressoria. Conidia were ellipsoid to ovoid and 30 to 45 (38) µm × 15 to 20 (16) µm. Conidiophores were erect, 80 to 120 (103) µm, consisted of a foot cell 42 to 67 (56) µm, and two to three short cells. Conidia were produced singly. On the basis of the observed morphological characteristics, the fungus was identified as Oidium neolycopersici L. Kiss (1). Pathogenicity tests were conducted on fourth true-leaf tomato seedlings cv. Reserve under greenhouse conditions (22 ± 5°C). Inoculation was performed by transferring conidia from infected leaves to the leaves of uninfected tomato seedlings with a single-edged razor blade. Powdery mildew symptoms began to develop 7 days after inoculation. Symptoms and morphological characteristics were similar to those observed in the commercial greenhouse. Noninoculated plants remained healthy throughout the experiments. To our knowledge, this is the first report of O. neolycopersici causing powdery mildew on tomato in Michoacan, Mexico. This disease has been reported from Canada, Europe, Japan, the United States (2), and Venezuela (3) on greenhouse and field tomato crops. The observed high incidence and severe infection indicates that this disease may become an important problem in greenhouse tomatoes in Mexico. References: (1) L. Kiss et al. Mycol. Res. 105:684, 2001. (2) L. Kiss et al. Plant Dis. 89:491, 2005. (3) J. O. Montilla et al. Plant Dis. 91:910, 2007.

First Report of Haplotype I-b of Phytophthora infestans in Central Mexico.

Central Mexico is considered a center of genetic diversity for Phytophthora infestans on the basis of a range of genotypic and phenotypic characteristics (3). Surprisingly, while mitochondrial DNA (mtDNA) haplotypes I-a, II-a, and II-b have been reported from central Mexico, haplotype I-b has not been found in central Mexico (1). Therefore, a more extensive search for haplotypes was conducted in areas where sexual reproduction occurs. During the summer of 2003, leaflets of cvs. Rosita and Tollocan with a single lesion of late blight were collected in the area of Villarreal, located in Terrenate County in Tlaxcala, Mexico (170 km northeast of Mexico City). Fourteen P. infestans isolates were characterized for mtDNA haplotype, isozyme genotype (glucose 6- phosphate isomerase [Gpi] and peptidase [Pep]), and mating type. Isolation, mating type, and isozyme genotype were characterized following reported protocols (1,4). MtDNA haplotype was determined by amplifying and digesting the P2 and P4 regions and comparing amplicons to those of reference strains of known haplotype (1,2). Twelve isolates were mtDNA haplotype I-a and two were I-b. While the mtDNA I-b has been associated with the US-1 lineage (mating type: A1, Gpi: 86/100, Pep: 92/100), the genotypes for the Mexican isolates were A2, 86/100 Gpi, 100/100 Pep from cv. Rosita and A2, 86/100 Gpi, 92/100 Pep from cv. Tollocan. To our knowledge, this is the first report of the I-b mtDNA haplotype of P. infestans from central Mexico and it is now clear that all four haplotypes exist in Mexico. This finding therefore, stresses the importance of including a representative regional sampling of Mexican and Andean isolates in studies inferring the origin of this species. References: (1) W. G. Flier et al. Phytopathology 93:382, 2003. (2) G. W. Griffith and D. S. Shaw. Appl. Environ. Microbiol. 64:4007, 1998. (3) N. J. Grünwald and W. G. Flier. Ann. Rev. Phytopathol. 43:171, 2005. (4) N. J. Grünwald et al. Phytopathology 91:882, 2001.

Ascorbate attenuates atrial pacing-induced peroxynitrite formation and electrical remodeling and decreases the incidence of postoperative atrial fibrillation.

Atrial fibrillation (AF), the most common chronic arrhythmia, increases the risk of stroke and is an independent predictor of mortality. Available pharmacological treatments have limited efficacy. Once initiated, AF tends to self-perpetuate, owing in part to electrophysiological remodeling in the atria; however, the fundamental mechanisms underlying this process are still unclear. We have recently demonstrated that chronic human AF is associated with increased atrial oxidative stress and peroxynitrite formation; we have now tested the hypothesis that these events participate in both pacing-induced atrial electrophysiological remodeling and in the occurrence of AF following cardiac surgery. In chronically instrumented dogs, we found that rapid (400 min(-1)) atrial pacing was associated with attenuation of the atrial effective refractory period (ERP). Treatment with ascorbate, an antioxidant and peroxynitrite decomposition catalyst, did not directly modify the ERP, but attenuated the pacing-induced atrial ERP shortening following 24 to 48 hours of pacing. Biochemical studies revealed that pacing was associated with decreased tissue ascorbate levels and increased protein nitration (a biomarker of peroxynitrite formation). Oral ascorbate supplementation attenuated both of these changes. To evaluate the clinical significance of these observations, supplemental ascorbate was given to 43 patients before, and for 5 days following, cardiac bypass graft surgery. Patients receiving ascorbate had a 16.3% incidence of postoperative AF, compared with 34.9% in control subjects. In combination, these studies suggest that oxidative stress underlies early atrial electrophysiological remodeling and offer novel insight into the etiology and potential treatment of an enigmatic and difficult to control arrhythmia. The full text of this article is available at http://www.circresaha.org.

First Report of Phytophthora capsici Causing Wilt on Hydropronically Grown Cucumber in Mexico.

During August 2005, wilted cucumber (Cucumis sativus cv. Tasty Green) plants were observed in a commercial greenhouse with a closed hydroponic system in the state of Mexico. Disease incidence was 50%. Diseased plants were detected 15 days after transplanting, when plants were overwatered. Yield was severely reduced when disease affected mature plants. Wilted plants showed basal stem lesions and root rot. Phytophthora capsici was consistently isolated from diseased tissue on corn meal agar (CMA) with tartaric acid. Oomycete identification was based on sporangial and gametangial characteristics (2). Sporangia produced on blocks of CMA at 25°C were spherical, broadly ellipsoid or obovoid with one papillae, and deciduous with a long pedicel (1). The isolates were heterothallic, and oogonia with amphigynous antheridia were observed in pairings with an A1 isolate of P. capsici, therefore, the isolates were determined to be an A2. Pathogenicity tests were conducted on 2-month-old cucumber seedlings under controlled conditions (25°C). Inoculation was performed by placing small pieces of agar with mycelium of 5- to 7-day-old cultures on the stem base and wrapping with Parafilm. Control plants were inoculated with CMA agar. No symptoms were observed on the control. Plants inoculated with the P. capsici isolated from the diseased cucumbers showed a basal stem lesion, followed by wilting and death 7 to 14 days after inoculation. The isolate was also pathogenic on tomato and eggplant that were grown at the same time in the commercial greenhouse sharing the nutrient solution. P. capsici sporangia were observed on the roots of both hosts. To our knowledge, this is the first report of P. capsici affecting cucumber in a hydroponics system in Mexico. References: (1) M. Aragaki and J. Y. Uchida. Mycologia 93:137, 2001. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society. St. Paul MN, 1996.

First Report of Gladiolus Rust Caused by Uromyces transversalis in Michoacán, México.

During October 2005, rust lesions were observed on leaves of gladiolus (Gladiolus sp.) plants being grown for flower production in a 20-ha field in eastern Michoacán, México. Disease incidence was near 100% in the field. Five symptomatic plants were collected on 11 and 25 October 2005, from each of 10 farms for further examination. Uredinia were scattered, orange, elliptical to irregular, and arranged transversely across the leaf. The sori were covered by the epidermis initially and later were erumpent and pulverulent. Urediniospores were bright yellow gold, ovate to oblong, and measured 15 × 19 µm (average). The urediniospore wall was hyaline and minutely echinulate. Telia were scattered, dark brown, elliptical, arranged transversely across the leaf, and were covered by the epidermis. Teliospores were irregularly pyriform, ovate, irregular or angular, light to dark brown with a conical or truncate apex and measured 17 × 23 µm (average). The teliospore wall measured 1 µm (average) thick at the sides and 3 µm (average) thick at the apex. Pedicels were light yellow and measured as much as 60 × 3 µm (average). On the basis of these characters, the rust was identified as Uromyces transversalis (Thüm.) G. Winter (1). To our knowledge this is the first report of U. transversalis causing gladiolus rust in Michoacán, México. Originally reported from Africa, the disease has been reported from Argentina, Brazil, southern Europe, and Oceania (1). Gladiolus rust caused by Uromyces transversalis is a quarantine disease for Europe and the United States. There have been unpublished reports of interceptions of this rust on cut flowers of gladiolus going from México into the United States (1). References: (1) J. R. Hernández. Invasive Fungi. Gladiolus Rust. Systematic Botany and Mycology Laboratory, Online publication. ARS, USDA, 2004.

Ventricular tachycardias arising from the aortic sinus of valsalva: an under-recognized variant of left outflow tract ventricular tachycardia.

OBJECTIVES: To describe a normal heart left bundle branch block, inferior axis ventricular tachycardia (VT), that could not be ablated from the right or left ventricular outflow tracts. BACKGROUND: Whether these VTs are epicardial and can be identified by a specific electrocardiographic pattern is unclear. METHODS: Twelve patients with normal heart left bundle branch block, inferior axis VT and previously failed ablation were included in this study. Together with mapping in the right and left ventricular outflow tracts, we obtained percutaneous epicardial mapping in the first five patients and performed aortic sinus of Valsalva mapping in all patients. RESULTS: No adequate pace mapping was observed in the right and left ventricular outflow tracts. Earliest ventricular activation was noted in the epicardium and the aortic cusps. All patients were successfully ablated from the aortic sinuses of Valsalva (95% CI 0% to 18%). The electrocardiographic pattern associated with this VT was left bundle branch block, inferior axis and early precordial transition with Rs or R in V2 or V3. Ventricular tachycardia from the left sinus had rS pattern in lead I, and VT from the noncoronary sinus had a notched R wave in lead I. None of the patients had complications and all remained arrhythmia-free at a mean follow-up of 8 +/- 2.6 months. CONCLUSIONS: Normal heart VT with left bundle branch block, inferior axis and early precordial transition can be ablated in the majority of patients from either the left or the noncoronary aortic sinus of Valsalva.

Biventricular pacing for heart failure.

The completed trials of biventricular pacing in congestive cardiac failure are impressively encouraging as a novel therapy for the symptoms of a most devastating disease. The actual delivery of the LV pacing hardware and final patient selection criteria require further refinement, as it is clear that not all patients with heart failure respond favorably. What is clear is that all patients should be prescribed maximally tolerated, proven medical therapy before assessment as to the feasibility of biventricular pacing therapy. This should be the case until potentially proven otherwise in newly planned trials designed to assess the comparative efficacy of both approaches. It is difficult to see that the two approaches should be anything but complementary in their benefit. The expense and potential complication associated with any invasive procedure needs to be considered, however, and it would seem reasonable that all of these patients should be receiving maximally tolerated medical therapy before and after the implantation of a device. Finally, the effect of this therapy on mortality needs to be assessed and, consequently, the requirement for defibrillation capability considered in this population of patients with a known high incidence of sudden death.

Preventing sudden death in coronary cardiomyopathy: implantable defibrillators lead the way.

The Multicenter Unsustained Tachycardia Trial (MUSTT) demonstrated that electrophysiologic testing (EP)-guided therapy significantly reduces arrhythmic death and cardiac arrest in patients with coronary artery disease, a left ventricular ejection fraction of 40% or less, nonsustained ventricular tachycardia, and inducible ventricular arrhythmia on EP testing-but only if the therapy includes an implantable defibrillator. All patients who meet the MUSTT inclusion criteria should undergo an EP test and if positive, should undergo defibrillator implantation.

First Report of Ovulariopsis on Lupinus havardii.

In 1998 and 1999 a severe powdery mildew was observed in Las Cruces, NM, on Big Bend Bluebonnets (Lupinus havardii) grown in the greenhouse for cut flowers and vase life studies. An undescribed powdery mildew has been reported on L. havardii (2), but it has been observed only occasionally on leaves and has not cause a severe problem. The powdery mildew observed in Las Cruces began in March and caused severe infection from May through July. The disease spread rapidly due to movement of the pathogen during pruning operations and the close proximity of plants. Plants were heavily infected when no fungicide was applied. Plants were sprayed with the fungicide azoxystrobin, with best control obtained at 687 mg/liter of water. When an infected plant was used as a source of inoculum, disease spread rapidly to healthy plants placed around the infected plant. Infected leaves had chlorotic lesions that later became necrotic. Mycelia, conidiophores, and conidia of the pathogen were observed on leaves and occasionally on petioles and stems. Ellipsoid cylindrical-to-clavate conidia were hyaline, one-celled, and measured 49 to 68.1 µm × 12.2 to 14.7 µm. Conidia were produced on upright, simple conidiophores measuring 171 to 245 µm × 4.9 to 7.3 µm. Fibrosin bodies and cleistothecia were not found. The fungus was identified as an Ovulariopsis sp. (1). This is the first documented report of an Ovulariopsis sp. on L. havardii. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) W. A. Mackay and T. D. Davis. HortScience 33:348, 1998.

First Report of Pythium paroecandrum on Lupinus havardii.

Lupinus havardii Wats. (Big Bend Bluebonnet), a plant native to Texas, has been tested extensively for greenhouse production as a cutflower crop (1). Disease symptoms were observed on L. havardii plants grown in Las Cruces, NM, during two consecutive years. Plants were grown in Metro Mix 200 and watered by an automatic irrigation system every 3 days. During the growing season, which extended from September through February, 6% of mature plants (10-week-old plants) became chlorotic, wilted, and died. The first symptoms were observed during December 1998, when greenhouse temperatures were from 10 to 13°C. During the rest of the growing season, from February to July, only one plant became diseased, during May 1999, and the plant died within 1 week after greenhouse temperatures reached 20 to 25°C. Diseased plants were examined, and root, crown, and stem rot were found. Pythium paroecandrum Drechs. (2) was isolated routinely from infected tissues. Koch's postulates were fulfilled after plants were inoculated with oospores and mycelia of P. paroecandrum. Inoculum was applied next to the crown of 6-week-old plants in the form of water-agar plugs and a suspension that contained P. paroecandrum oospores and mycelia. Plants were maintained at 20 to 25°C. After 10 days, symptoms were similar to those previously observed, and the pathogen was reisolated from necrotic lesions observed on stems and crowns. Disease developed slower on 6-week-old plants (inoculated) than on 10-week-old plants (naturally infected). This is the first report of P. paroecandrum on L. havardii. References: (1) W. A. Mackay and T. D. Davis. HortScience 33:348, 1998. (2) A. J. Van der Plaats-Niterink. Monograph of the genus Pythium. Studies Mycol. 21:1, 1981.

First Report of Verticillium dahliae Causing Wilt on Solanum cardiophyllum and Solanum ehrenbergii.

Solanum cardiophyllum Lindl and Solanum ehrenbergii (Bitt) Rydb are wild edible potato plants found throughout central Mexico (2). These plants are not cultivated, but farmers collect tubers for their own consumption and to sell at local markets (2). Wilted plants were observed in experimental plots of these wild potatoes established near Chapingo, Mexico, during spring 1983. Initial symptoms included wilting and dark yellowing of lower leaves. As the disease advanced, all of the foliage became chlorotic and the plants wilted and eventually died. Disease incidence was 13.4% for S. ehrenbergii and 0.2% for S. cardiophyllum. Verticillium dahliae Kleb. was consistently isolated from the roots and lower stems of diseased plants of both Solanum species. The isolating procedure consisted of thoroughly rinsing roots and lower stems with tap water and cutting roots and stems into 3- to 6-cm sections that were placed in 10% bleach for 3 to 5 min. Bleach excess was removed with sterile paper, and the tissue sections were cut into smaller pieces (0.5 cm) and placed on potato dextrose agar (PDA) plates. Cultures of Verticillium produced numerous dark microsclerotia of various shapes and sizes (0.05 to 0.1 mm); erect, slender, hyaline, and branched conidiophores; and elliptical and hyaline, single-celled conidia characteristic of V. dahliae (1). Pathogenicity studies were conducted in a greenhouse on 2-month-old S. cardiophyllum and S. ehrenbergii plants grown from tubers. Inoculum was obtained from colonies growing on PDA for 10 days producing abundant conidia. Conidial suspensions were obtained by flooding the plate cultures with sterile distilled water, filtering the suspension with two layers of cheesecloth, and adjusting the inoculum to 1.0 × 106 conidia/ml (3). Ten ml of the conidial suspension were applied to each of four holes 5 cm deep and 3 to 5 cm next to the crown of each plant. Symptoms similar to those observed on field-grown plants were observed 15 days after inoculation, and V. dahliae was re-isolated from lower stems and roots. All inoculated plants were dead 4 weeks after inoculation. Water-inoculated plants remained healthy throughout the experiments. This is the first report of V. dahliae on S. cardiophyllum and S. ehrenbergii. References: (1) G. R. Dixon. Vegetable Crop Diseases. Avi Publishing, Westport, Connecticut. 1981. (2) J. Galindo. Naturaleza 13:175, 1982. (3) H. A. Melouk and C. E. Horner. Phytopathology 65:767, 1975.

Formation of Phytophthora infestans Oospores in Nature on Tubers in Central Mexico.

Oospore formation by Phytophthora infestans in nature has been detected on potato leaflets in central Mexico (1), but there are no reports of oospore formation on tubers. A severe late blight epidemic occurred in Calimaya, Mexico, in fields where potato cv. Alpha was planted during the summer of 2000. Yield was reduced despite numerous applications of fungicide. Four hundred potato tubers left in the field were collected from the upper 10 cm of soil and examined for late blight symptoms. Tubers with soft and dry rot symptoms were observed, but symptoms of pink rot (Phytophthora erythroseptica) were not found. Four percent of the tubers showed late blight symptoms. Sections of 10 tubers with late blight symptoms were air-dried for 2 weeks in the laboratory and homogenized with a mortar and pestle. Glycerol was added to the homogenized tissue and observed microscopically. Aplerotic oospores (10 to 15 oospores per tuber) with amphyginous antheridia typical of P. infestans were observed. P. mirabilis morphologically similar to P. infestans is present in the area but it does not infect potato tubers. The number of oospores observed in our tuber sample was much lower than the number reported on leaflets (>1,000 oospores per leaflet) in the Toluca Valley. Low numbers of oospores have been reported on tubers artificially inoculated with P. infestans under field conditions (2). Infected tubers left in the field may act as a source of primary inoculum. To our knowledge, this is the first report of oospores of P. infestans found on tubers in Mexico under natural field conditions. References: (1) M. E. Gallegly and J. Galindo. Phytopathology 48:274, 1958. (2) A. Levin et al. Phytopathology 91:579, 2001.