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La capacidad de intercambio catiónico (CIC) es una de las propiedades más importantes al evaluar la fertilidad del suelo. El método más usado es mediante acetato de amonio 1 N, pH 7.0; sin embargo, este método presenta errores durante la determinación. Se compararon varios métodos para medir la CIC: acetato de amonio (NH₄OAc) 1 N pH 7.0, acetato de sodio (NaOAc) 1 N pH 8.2, sumatoria de cationes extraídos con NH₄OAc 1 N a pH 7.0 (CICE), cloruro de bario (BaCl2) 0.01 M y tiourea de plata (AgTU) 0.01 M. Los suelos analizados tenían características variables en pH, textura, materia orgánica y carbonatos. Los mayores valores de CIC se obtuvieron con la sumatoria de cationes, seguidos por acetato de amonio y tiourea de plata. El método de acetato de sodio presentó valores intermedios debido a los errores del método. Hubo asociación entre la CIC mediante AgTU y NH₄OAc a diferencia de CICE y NH₄OAc; el costo de determinación con NH₄OAc superó en ocho al de AgTU. Los cationes Mg2+, K+ y Na+ extraídos mediante cloruro de bario, acetato de amonio y acetato de sodio presentaron alta asociación; sin embargo, no hubo relación entre K+ y Na+ extraídos con NH₄OAc y AgTU. El calcio fue el catión que más se sobreestimó, seguido del magnesio y potasio extraído con NH₄OAc 1 N a pH 7.0, donde la sobreestimación varió de 10 a 498 veces con relación al que originalmente está en los sitios de intercambio, mientras que el magnesio y potasio se sobreestimaron de 11.2 a 141.7 y de 3.7 a 33.3 veces, respectivamente. El método de AgTU fue la mejor alternativa para determinar la CIC, ya que es rápido, de bajo costo, minimiza errores y es aplicable a suelos con diferentes características de pH, textura, materia orgánica y contenido de carbonatos.

Euphorbia pulcherrima is a plant with colorful bracts sold mainly at Christmas time, and is the most important ornamental container plant in the world. To produce healthy plants with high-quality standards, growers intensively apply pesticides and fertilizers, which increases production costs and promote environmental pollution. Plant growth-promoting rhizobacteria (PGPR) represent an environmentally friendly technological alternative for ornamental production. Therefore, this work evaluated the effect of three bacteria (Pseudomonas sp. CPO 2.78, Enterobacter sp. CPO 2.5, and Bacillus megaterium CPO 2.35) isolated from the rhizosphere of E. cyathophora on the vegetative and reproductive growth of E. pulcherrima var. Prestige Red in the presence of three doses of multipurpose Ultrasol fertilizer (0, 50% and 100%) after 236 days under greenhouse conditions. At vegetative stage (118 days), bacterial inoculation produced greater leaf area and higher leaf weight, total dry weight, and relative chlorophyll content, especially with the 50% fertilizer combination. At reproductive stage (236 days), inoculating a mixture of the three bacteria combined with 50% fertilizer increased leaf area, chlorophyll content, total dry weight, plant width, and number of branches. Overall, using PGPR plus 50% fertilizer improved growth and produc- tion of E. pulcherrima, and obtained a plant quality similar to that achieved without inoculation plus 100% fertilization.

Sorghum is cultivated in tropical and subtropical regions of the world and is an important cereal for Mexico. However, it is affected by different pests, especially the yellow aphid. The objective of the research was to evaluate the effectiveness of biological, botanical and chemical insecticides in reducing Melanaphis sacchari populations in sorghum plants under greenhouse conditions. Planting was conducted in a greenhouse, using the sorghum hybrid 945-M. Pests, diseases and weeds management were implemented. The incidence of the yellow aphid was induced artificially. A total of 13 treatments were applied. The following variables were assessed: the number of aphids per leaf, the biological effectiveness of the treatments, plant height, diameter of the plant stem, number of leaves, and the weight of fresh and dry plants. An analysis of variance was conducted for each variable under study, as along with a comparison of means using the Tukey method (α=0.05) and correlation analysis using the SAS® 9.4 software. The chemical, biological and organic insecticide that exhibited the greatest control of the yellow aphid (more than 95%) were: Toretto® (sulfoxaflor), PHC® Meta Tron® (M. anisopliae), Bio-Die® (Argemonin, Berberine, Ricinin and a-Terthienyl). Adequate management strategies are needed to avoid health problems in people, environmental contamination and resistance or multiple resistance.

Se evaluó un nuevo sistema de monitoreo para Hypothenemus hampei Ferrari en el cultivo de café Coffea arabica L. en la región de Coatepec, Veracruz, México. Los tratamientos con atrayentes probados fueron: T1=metanol+etanol (3:1), T2=vinagre de manzana+etanol (3:1), T3=vinagre blanco+etanol (3:1), T4=vinagre de manzana+etanol (1:1), T5=vinagre blanco+etanol (1:1) y T6=etanol al 96° colocados en trampas artesanales durante un año. Con la prueba de Tukey se demostró que el mejor tratamiento fue el T5 con una media de 52,00 capturas, le siguió T3 con 39,65 individuos y T1 con 24,15 hembras, el T2, T4 y T6 no mostraron una respuesta significativa. La investigación aporta a los cafeticultores de subsistencia, un nuevo atrayente para el monitoreo de la broca del café con vinagre blanco más etanol en la proporción 1:1, ya que resultó efectivo, económico, no tóxico para la salud humana y amigable con el ambiente.

En el ciclo agrícola primavera-verano de 2016 se evaluaron los híbridos P4082W, H565 y DK357 con fertilización química y química + biológica mediante un experimento factorial en arreglo de parcelas divididas. En los tratamientos con biofertilizante se inoculó la semilla con Glomus intraradices + Azospirillum brasilense; en la fertilización química se aplicó 120N-80P-80K. Se midieron las variables: altura, diámetro del cuello y número de hojas de la planta, número y peso de mazorcas con y sin brácteas, peso de brácteas, longitud y diámetro de la mazorca, número de hileras mazorca-1, peso de grano de 5 mazorcas, longitud, diámetro y peso del olote, rendimientos de grano, de forraje zacateado y de molido seco; para determinar la rentabilidad de los sistemas se calcularon el costo total (CT), ingreso total (IT), ingreso neto (IN) y la ganancia por peso invertido (GPI). El análisis estadístico incluyó análisis de varianza y prueba de comparaciones de medías con el método de Tukey. Se encontró que el híbrido DK357 registró la mayor altura, número de hojas, peso de grano, longitud de mazorca y del olote, rendimiento de grano y forraje tanto zacateado como molido seco. El genotipo P4082W obtuvo el mayor peso de mazorca con y sin brácteas. La fertilización química favoreció el rendimiento de forraje zacateado, y en combinación con la biológica, incrementó el rendimiento de grano. Los híbridos DK357 y P4082W cultivados con fertilización química y biológica resultaron rentables en los sistemas para producción de grano solo, forraje zacateado y grano y forraje seco molido.

The aphid Melanaphis sacchari/sorghi is considered the most important pest of sorghum cultivation in Mexico. It can cause losses in production of up to 100%. This research was conducted at the Universidad Autonoma Chapingo during 2018 and 2019 with the objective of determining the relationship between chemical fertilization in sorghum and M. sacchari/sorghi (Hemiptera: Aphididae) populations. Different levels of nitrogen (125, 250 and 500 kg ha-1), phosphorus (19.5, 39 and 78 kg ha-1) and potassium (210 and 420 kg ha-1) were supplied to sorghum plants planted in polyethylene pots with a capacity of 6 L under greenhouse conditions. The plants were infested with a total of 15 third-instar nymphs within 60 days of crop emergence. A total of 6 samplings were carried out at 7 day intervals, starting at 7 d after the infestation. Quantifications of total soluble proteins, total soluble sugars, reducing sugars, and levels of nitrogen, phosphorus, potassium and magnesium in leaf tissue were also performed. We observed that higher doses of nitrogen and phosphorus increased the aphid population, while increasing the potassium dose considerably decreased the aphid population. We also found a positive correlation between the aphid population and the total soluble protein concentrations, reducing sugars and nitrogen levels, while the correlation was negative with potassium levels in leaves.

The filamentous Ascomycota Colletotrichum gloeosporioides sensu lato is a fungus that has been reported worldwide as a causal agent of anthracnose disease in avocado and other crops. In Mexico, this species affects fruits from an early stage of development in the orchard until the post-harvest stage. Although fungicides are continuously applied to control Colletotrichum species, pericarp cankers and soft rot mesocarp in fruits are still frequently observed. Considering the lack of a precise description of the causative agent, the aim of the current study was to determine the pathogens involved in this symptomatology. Twenty-four isolates were consistently obtained from the pericarp of avocado fruits cv. “Hass” collected in the central avocado-producing area of Mexico. Morphological features such as colony growth, conidia size, and mycelial appressorium were assessed. Bayesian multilocus phylogenetic analyses were performed using amplified sequences of the internal transcribed spacer region of the nuclear ribosomal DNA; actin, chitin synthase, glyceraldehyde-3-phosphate dehydrogenase partial genes; and APn2-Mat1-2 intergenic spacer and mating type Mat1-2 partial gene from the nine selected isolates. In addition, fruits were inoculated with a conidial suspension and reproducible symptoms confirmed the presence of Colletotrichum fructicola in this area. This pathogenic species can now be added to those previously reported in the country, such as C. acutatum, C. boninense, C. godetiae, C. gloeosporioides, and C. karstii. Disease management programs to reduce the incidence of anthracnose should include C. fructicola to determine its response to fungicides that are routinely applied, considering that the appearance of new species is affecting the commercial quality of the fruits and shifting the original population structure.

L a calabaza pipiana es importante en la alimentación de la población en el centro-sur de México . Sus semillas se consumen directamente tostadas y aderezadas con sal; además, son el ingrediente principal para elaborar platillos típicos como el mole verde o pipian, así como diferentes dulces tradicionales. Algunos microorganismos del suelo causan severos problemas en frutos, lo que afecta el rendimiento. El objetivo del estudio fue identificar morfológica y molecularmente al oomicete causante de la pudrición de frutos de calabaza pipiana, y evaluar opciones de control químico y biológico en invernadero. Durante agosto y septiembre de 2011, en la zona norte del estado de Guerrero, se colectaron frutos de calabaza pipiana con síntomas de pudrición. La identificación morfológica se realizó con las claves propuestas por Gallegly y Hong (2008), y la molecular fue mediante la reacción en cadena de la polimerasa, ITS-PCR. En ambas pruebas se identificó a Phytophthora capsici como el causante de la pudrición de frutos de calabaza pipiana. Las secuencias obtenidas tuvieron 99 % de similitud con P. capsici en sandía de Estados Unidos y en calabaza de Italia, depositadas en el banco de genes (GenBank). Los ingredientes activos, propamocarb+fosetil y metalaxil+clorotalonil, mostraron control al retrasar seis días la presencia del patógeno en frutos, mientras que los agentes de biocontrol la retardaron cuatro días.

En México, la mayoría de los árboles de mamey (Pouteria sapota (Jacq.) H. E. Moore and Stearn) tienen una altura mayor a 10 m, lo que dificulta la operación de cosecha, por lo que es frecuente el daño en los frutos. Asimismo, su conservación en distintos empaques causa deterioro en grado diferente. Cinco técnicas postcosecha de fruto se evaluaron para medir su efecto en la calidad durante el almacenamiento: T1, cosechados sin daño alguno, empacados individualmente en cajas de cartón; T2, lanzados desde 10 m de altura, capturados en costal de yute y empacados a granel en caja de plástico; T3, lanzados desde 10 m de altura a un colchón y empacados a granel en caja de plástico; T4, lanzados desde 4 m de altura a suelo húmedo y empacados a granel en caja de plástico; y T5, lanzados desde 10 m de altura, capturados en costal de yute y empacados en un costal de yute. Los frutos se almacenaron a temperatura ambiente (25 ± 1 °C); su calidad se evaluó a 1, 3, 5, 7 y 9 días después de la cosecha (DDC). El tratamiento T1 comparado con T4 y T5 (7 y 9 DDC) registró la mayor firmeza, menor actividad de pectinmetilesterasa y contenido de sólidos solubles totales (°Brix); así como los menores cambios en brillo (L*) y croma (C). En ángulo de tono (H) se presentaron diferencias a los 9 DDC, donde T1 mostró valores mayores que T5. No hubo diferencias en porcentaje de ácido málico y pérdida de peso entre tratamientos.

The consumption of fresh nopal cactus juice is widely popular among health-conscious consumers in Mexico. The juice is prepared from fresh cladodes that have only been rinsed with tap water and are not subjected to a pasteurization or terminal bacterial reduction process. The aim of this study was to evaluate the microbial quality of commercially available fresh juices (n = 162) made with nopal in Texcoco, State of Mexico, during the summer and spring season. Standard microbiological methods, the PCR technique and the serological method were used for isolation and identification of bacteria. All samples contained total coliforms and 91% were positive for Escherichia coli. Although total coliforms and E. coli were detected throughout the study, their populations were significantly lower (p < 0.05) in winter and spring, respectively. Citrobacter youngae was found in 20% of the samples, an unidentified species of Citrobacter in 10%, C. freundii and Proteus mirabilis in 3%, and Salmonella Javiana in 1%. The presence of these microorganisms, especially Salmonella, in the nopal juices is unacceptable due to its health significance. The information generated in this study is relevant for human health risk assessment associated with the consumption of unpasteurized nopal juices and potential interventions to minimize pathogen contamination.

Background: recently there has been concern for the monitoring of ambrosial complexes in Mexico that consist of a symbiotic relationship between a beetle and fungi, where the female invades a wide variety of species making galleries in the bark and wood, in which beetles reproduce and grow the fungi to feed the colony, these fungi can be a phytopathogen that can cause serious damage in the infected trees. The proximity of Raffaelea lauricola now present in Texas and the presence of Fusarium euwallacea in the north of Mexico; fungi that have caused great losses in the United States, put in risk the avocado production zones in Mexico. Consequently, the report of new fungi related to ambrosial complexes is of great importance. Objective: to carry out pathogenicity tests of fungi related to ambrosial complexes in avocado ‘Hass’. Methodology: Isolates of Raffaelea brunnea, Ceratocystiopsis sp. (pre-identified) and Fusarium sp., from avocado trees parasitized with ambrosial beetles from the state of Michoacán and an unidentified fungus from Chiapas (Mexico) were used. Artificial inoculations with the fungi were carried out by wounds in mature stem and shoots of the growth of the year (young) of ‘Hass’ plants, and the symptoms and the progress of the damage within the stem were evaluated. Three of the isolates underwent a molecular identification analysis with the complete region of the ITS internal transcript space. Results: the fungus Ceratocystiopsis sp. was identified as Ophiostoma sp. and Fusarium sp. such as Fusarium solani, both isolated from Michoacán. While the Chiapas fungus was identified belonging to the genus Fusarium. After inoculation, R. brunnea and Fusarium sp. stood out in pathogenicity, with greater advancement within the stem and damage that in some cases reached the pith tissue, showing leaf wilting and reddish-brown staining inside the stem. These two fungi showed differential damage progression behavior according to the type of maturity of the tissue, where Fusarium sp. advanced more in the young tissue and R. brunnea in the mature one. Implications: it is proposed to consider that the study was only carried out in ‘Hass’, thus this may be an important factor, since probably if the fungi were inoculated in more varieties, differences in behavior of the advance in damage of these could be found. Conclusions: all the fungi showed to be pathogenic with variation in severity. In terms of Raffaelea brunnea, a peculiar behavior was found in the severity of internal and external damage, in which external symptoms may or may not occur, strictly in ‘Hass’ avocado plants 30 days after inoculation.

Fruit rot is the principal phytopathological problem of pipiana pumpkin (Cucurbita argyrosperma Huber) in the state of Guerrero. The aims of this research were to 1) identify the causal agent of southern blight on pumpkin fruits by morphological, pathogenic, and molecular analysis (ITS1, 5.8S, ITS2); 2) evaluate in vitro Trichoderma spp. strains and chemical fungicides; and 3) evaluate under rainfed field conditions, the strains that obtained the best results in vitro, combined with fungicides during two crop cycles. Number of commercial and non-commercial fruits at harvest, and seed yield (kg ha−1) were registered. Morphological, pathogenic and molecular characterization identified Sclerotium rolfsii as the causal agent of rot in pipiana pumpkin fruits. Now, in vitro conditions, the highest inhibition of S. rolfsii were obtained by Trichoderma virens strain G-41 (70.72%), T. asperellum strain CSAEGro-1 (69%), and the fungicides metalaxyl (100%), pyraclostrobin (100%), quintozene (100%), cyprodinil + fludioxonil (100%), and prochloraz (100%). Thiophanate-methyl only delayed growth (4.17%). In field conditions, during the spring-summer 2015 cycle, T. asperellum strain CSAEGro-1 + metalaxyl, and T. asperellum + cyprodinil + fludioxonil, favored the highest number of fruits and seed yield in the crop.

ABSTRACT: Euphorbia cyathophora Murray is a plant species with medicinal and ornamental potential but whose in vitro propagation is unknown. Two experiments were performed to know 1) the effect of light (WL) at 25±2 °C and 20 μmol m-2 s-1 luminous intensity, or darkness at 20±2 °C, for the first 20 days and subsequent placement in light (DKL) as previously described, and 2) the best combination of plant growth regulators: benzyl amino purine (BAP), kynetin (KIN), 2-isopentenyl adenine (2iP) and thidiazuron (TDZ) in combination with naphthaleneacetic acid (NAA) and the effect of both light conditions. The DKL treatment did not promote the growth of leaves, cotyledons, or plantlet height; in contrast, WL produced a more developed root system with early appearance of tertiary roots. In regards to the interaction of plant regulators and light effect, only the treatment with 1 mg BAP L-1 and 0.1 mg NAA L-1 generated shoots in both light conditions (DKL and WL). Darkness (DKL) generated more indirect greatest morphogenic responses (callus formation).

Mexico is the largest avocado ( Persea americana ) producer and exporter in the world. In January of 2019, typical symptoms of fruit anthracnose were observed on approximately 90% of avocado trees in backyards localized in Leonardo Bravo municipality in Guerrero, Mexico. Lesions on avocado fruits were circular, necrotic, and sunken, whereas the mesocarp showed a soft rot with dark brown discoloration. To perform fungal isolation, small pieces from adjacent tissue to lesions of five symptomatic fruits were surface disinfested by immersion in a 1% sodium hypochlorite solution for 2 min, rinsed in sterile distilled water, and placed in Petri dish containing potato dextrose agar (PDA). Plates were incubated at 25 ºC for 5 days in darkness. Colletotrichum -like colonies were consistently isolated and seven monoconidial isolates were obtained. An isolate was selected as a representative for morphological characterization, molecular analysis, and pathogenicity tests. The isolate was deposited in the Culture Collection of Phytopathogenic Fungi at the Colegio Superior Agropecuario del Estado de Guerrero (Accession No. CSAEG-CJ19). After 8 days on PDA, the colonies were gray on the upper surface, and with orange conidial masses. Conidia ( n = 100) were cylindrical, hyaline, aseptate, with rounded ends, 14.4 to 18.5 × 4.5 to 6.2 μm. Based on morphological features, the isolate was tentatively identified in the C. gloeosporioides species complex (Weir et al. 2012). For molecular identification, genomic DNA was extracted and the internal transcribed spacer (ITS) region of rDNA, and partial sequences of actin (ACT), β-tubulin (TUB2), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were amplified by PCR, and sequenced with primers ITS5/ITS4 (White et al. 1990), ACT-512F/ACT-783R (Carbone and Kohn 1999), Bt2A/Bt2B (Glass and Donaldson 1995), and GDF/GDR (Templeton et al. 1992), respectively. BLAST analysis of the obtained sequences of the ITS, ACT, TUB2, and GAPDH genes revealed 100%, 99.63%, 99.77% and 100% identity with those of isolate LF687 of C. jiangxiense in GenBank (Accession numbers KJ955201, KJ954471, KJ955348, and KJ954902). A phylogenetic tree based on Bayesian inference and including published ITS, ACT, TUB2, and GAPDH data for Colletotrichum species was constructed. The multilocus phylogenetic analysis clearly distinguished the isolate CSAEG-CJ19 as C. jiangxiense separating it from all other species within the C. gloeosporioides species complex. The sequences were deposited in GenBank (accession numbers ITS:MT011397; ACT:MN968784, TUB2:MN968786, and GAPDH:MN968785). To conduct Koch's postulates, 20 healthy avocado fruits (cv. Hass) were wounded with a sterile toothpick (2 mm in depth) and a drop of 15 µl of conidial suspension (1 × 10 5 spores/mL) was placed on each wound. Ten control fruit were wounded and treated with sterilized water. All the fruits were kept in a moist plastic chamber at 25°C for 8 days. All inoculated fruits developed circular and necrotic lesions (12 to 18 mm in diameter), 5 days after inoculation, whereas control fruits remained healthy. The fungus was consistently re-isolated from the inoculated fruits. Previously, C. jiangxiense has been reported as a pathogen on Camellia sinensis and Citrus sinensis in China (Farr and Rossman 2020). To our knowledge, this is the first report of C. jiangxiense causing anthracnose on avocado worldwide. This study shown another species in the C. gloeosporioides complex associated with avocado diseases in Mexico. Therefore, it is necessary to explore the diversity of Colletotrichum species in detail through subsequent phylogenetic studies as well as to monitor the distribution of this pathogen into other Mexican regions.