Las plantaciones de árboles de navidad con la especie Pseudotsuga menziesii (Mirb.) Franco ocupan 10% de la superficie total de este tipo de plantaciones en México. El tizón suizo es una enfermedad propia de del género Pseudotsuga, originada por el hongo Phaeocryptopus gaeumannii (T. Rohde) Petrak (1938). Los principales síntomas incluyen follaje clorótico y abscisión prematura de acículas infectadas, lo que resulta en copas ralas. El objetivo de este estudio fue determinar la relación entre la fertilización química y el estado nutrimental de los árboles con los niveles de severidad e incidencia de la enfermedad. La hipótesis fue que hay una correlación entre el estado nutrimental y la variación del grado de infestación del tizón suizo en P. menziesii. El estudio se estableció en el predio multifuncional “El Manantial” en Aquixtla, Puebla. Los tratamientos fueron fertilización con urea y sulfato de potasio y control fitosanitario químico con propiconazol y prochloraz. El diseño experimental fue bloques al azar generalizado, evaluando dos factores controlados con tres niveles (factorial 32) y como factor de confusión o bloqueo el nivel visual de transparencia de copa asociado al tizón suizo. La incidencia y la severidad se evaluaron. Los resultados del ANDEVA no indicaron diferencias significativas. De las variables nutrimentales las de mayor asociación a la severidad e incidencia fueron el contenido de Ca y Mn, y en menor medida, Cu, Mg y N. Entre los tratamientos se observaron antagonismos y sinergismos con efecto en el estado nutrimental. Los fungicidas influyen en la absorción, transporte y asimilación de los nutrimentos.
Se reporta la asociación del descortezador exótico Scolytus schevyrewi y el barrenador ambrosial Euwallacea ca. fornicatus, en árboles de parques, jardines y camellones de la ciudad de Tijuana, Baja California, México.
Blue-stain. Mexico. Ophiostoma pulvinisporum. PCR. White pine White pine or Acalocote [Pinus chiapensis (Mart.) Andresen] is an endemic species from Mexico that has been used in commercial forest plantations. In September 2014, pine wood samples with symptoms of damage by Ips calligraphus Germar and fungal blue stain were collected in Mazolapa, Hueytamalco, Puebla. The wood contained perithecia with dark globose bases, 186-197 μm in diam., ornamented with aseptate hyphae, 70 × 1.8 μm. Perithecial necks were dark brown, 980-984 μm long, 44-50 μm wide at base, 19-24 μm wide at the apex. Ostiolar hyphae were absent and asci not observed. Ascospores were hyaline, aseptate, pillowshape, 3.8-4.3 × 1.7-2.2 μm. Small pieces of wood were surface disinfected for 1 min, rinsed in sterile distilled water, and plated onto Malt Extract Agar (MEA). A fungus was isolated whose colonies were initially light gray at 10 days but turned dark gray with age. A reference specimen (UCH-DCF303) was deposited in the herbarium of the Forest Sciences Division of the Autonomous University of Chapingo, Texcoco, Mexico. Amplification of ITS was carried out using primers ITS4 and ITS5 (White et al. 1990). The PCR product (479 bp) was sequenced and deposited in GenBank (accession No. MK382983). The obtained sequence showed 99% similarity to the ex-type sequence of Ophiostoma pulvinisporum X. D. Zhou & M. J. Wingfield, (AY546714, isolate CMW9022). Based on morphological and molecular characteristics, the fungus observed on Pinus chiapensis was identified as Ophiostoma pulvinisporum. O. pulvinisporum was described from galleries of bark beetles in Pinus pseudostrobus and P. maximinoi in México. It has also been found in P. contorta in Canada (Zhou et al. 2004). This is the first report of this fungus on Pinus chiapensis in Mexico, extending the host range of the fungus and vector.
The decline and death of palms (Phoenix canariensis) in Mexico City is a problem that has increased in the last five years, causing the death of more than 500 palms and others with different degrees of damage. The causal agent has not been determined, so the present study aimed to identify the associated fungi of the decline and death of palms (Phoenix canariensis) in Mexico City. From February to August 2022, samples of symptomatic plant tissue from the trunk, petiole, rachis, and leaflets were collected at nine representative sampling sites in seven Boroughs of Mexico City. A total of 144 fungal isolates were obtained, comprising 11 different species. The species with the highest frequency were: Nalanthamala vermoesenii, Lasiodiplodia sp., Neopestalotiopsis sp., and Serenomyces sp., present mainly on the petiole and rachis; and Alternaria alternata and Phoma glomerata in the leaflets, these species have been reported as causative agents of different diseases in other countries and are reported for the first time in Mexico associated with P. canariensis. The information generated will allow establishing management measures tending to reduce the death of palms.
In Mexico City, the Canary Island date palm (Phoenix canariensis Chabaud) is an important plant forming part of its landscape identity. In February 2022, pink rot disease symptoms were observed on 16 P. canariensis plants in Mexico City (19°25'43.98"N, 99° 9'49.41"W). The incidence was 27%, while the severity 12%. External symptoms included necrotic lesions that advanced from the petiole towards the rachis. Internal symptoms were rotted, dark brown discoloration in bud, petiole, and rachis. Abundant conidial masses were developed on the infected tissues. Pieces of diseased tissues (5-mm cubes) were surface sterilized for 2 min in 3% sodium hypochlorite, rinsed with sterilized distilled water, plated onto potato dextrose agar (PDA), and incubated at 24°C and 12-h photoperiod, 20 pink fungal colonies were developed with sparse aerial mycelia on PDA. Conidiophores were hyaline, dimorphic, penicillate, and Acremonium-like. Conidia were dimorphic, typically with somewhat truncated ends, 4.5 to 5.7 × 1.9 to 2.3 μm (mean 4.99 × 2.15, n = 100), borne in long chains on penicillate conidiophores; on Acremonium-like conidiophores conidia were cylindrical, straight, and slightly curved, 4.55 to 10.1 × 1.2 to 2.35 μm (mean 8.2 × 1.7, n = 100). These morphological characteristics resembled those of Nalanthamala vermoesenii (Biourge) Schroers (Schroers et al. 2005). Genomic DNA was extracted from the mycelia of a representative isolate CP-SP53. The internal transcribed spacer (ITS) region and the large subunit of ribosomal ribonucleic acid (LSU) were amplified and sequenced. The sequences were deposited in GenBank with accession numbers OQ581472 (ITS) and OQ581465 (LSU). Phylogenetic trees based on ITS and LSU sequences of Nalanthamala species were reconstructed using maximum likelihood and Bayesian inference methods. Isolate CP-SP53 was placed in the clade of Nalanthamala vermoesenii. The pathogenicity test was carried out twice with isolate CP-SP53 on five 3-year-old P. canariensis plants. Four petioles per plant were surface disinfected with 75% ethanol, and wounded with a sterilized scalpel (shallow cuts 0.5 cm wide). A mycelial plug (5 mm in diam.) of a 1-week-old PDA culture was placed on each wounded site. Sterile PDA plugs were used for five non-inoculated control plants. All plants were maintained at 22 ± 2°C and a 12-h photoperiod. Twenty-five days after inoculation (dai), wounded petioles showed the same symptoms observed in the field, whereas control plants remained healthy. Forty-five dai, all inoculated plants died. Pink conidial masses developed on symptomatic tissues. To fulfill Koch’s postulates, the pathogen was reisolated by placing the pink conidial masses onto PDA. The colony characteristics and morphometric measurements were identical to those of isolate CP-SP53. Nalanthamala vermoesenii has been reported on P. canariensis in Greece and United States (Feather et al. 1979; Ligoxigakis et al. 2013) and Syagrus romanzoffiana in Egypt (Mohamed et al. 2016). To our knowledge, this is the first report of Nalanthamala vermoesenii as the causal agent of pink rot on P. canariensis in Mexico. This plant is the most commonly planted ornamental palm in Mexico City. The spread of N. vermoesenii could be a threat for the estimated 15 thousand palms, therefore dramatically change the urban landscape.
<p>La pimienta gorda se ha visto afectada por antracnosis, enfermedad que ataca frutos provocando manchas marrón-oscuras hundidas, hasta necrosar los frutos. Entre 2015-2016 en el norte de Veracruz se colectaron frutos de pimienta gorda con y sin síntomas de antracnosis, de estos se obtuvieron 13 cultivos monospóricos; posteriormente fueron caracterizados morfológica, patogénica y molecularmente. Para la caracterización morfológica los aislados se sembraron en medio de papa dextrosa agar y descritos mediante 11 variables. Para la caracterización patogénica fueron inoculados en frutos de pimienta gorda de tres localidades, con y sin herida previa a la inoculación, los testigos fueron tratados con agua destilada estéril. Se evaluó la incidencia y severidad. Para la caracterización molecular se extrajo el ácido desoxirribonucleico por el método de extracción y purificación CTAB. La región del ITS fue amplificada con los primers ITS4, ITS5. La caracterización morfológica identificó dos especies: <em>C. acutatum</em> y <em>C. gloeosporioides</em>. Todos los aislados resultaron patogénicos en los frutos después de 11 días de la inoculación. Molecularmente se confirmaron los resultados de la identificación morfológica y de dos especies adicionales: <em>C. fragariae</em> y <em>C. boninense</em>.</p>
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