Abstract. Phytopathogenic fungi can cause economic losses. The application of natural products from species of the genus Agave is an alternative for controlling these organisms. The present study aimed to determine the phytochemical profile of Agave angustifolia and A. cupreata extracts and to evaluate their antifungal activity against several species of phytopathogenic fungi. The aqueous extract from A. angustifolia and the acetonic extract from A. cupreata were studied. The phytochemical profile was determined by thin-layer chromatography. Mycelial growth inhibition and spore production were evaluated. Phytochemical screening revealed the presence of alkaloids, flavonoids, saponins, and triterpenes. The acetonic extract of A. cupreata inhibited 76, 60, and 59% of the mycelial growth of Lasiodiplodia viticola, Colletotrichum sp., and Epicoccum sorghinum, respectively, at 8 and 16 mg mL-1 (p≤0.05), while spore production decreased by 92 and 86 % (p≤0.001) for Fusarium subglutinans and Colletotrichum sp., respectively. The aqueous extract of A. angustifolia inhibited 40% of the mycelial growth of E. sorghinum at 16 mg mL-1 (p≤0.05) and reduced the spore production of L. viticola by 35% (p≤0.001). The results indicate that the extracts under study can be an alternative source of antifungal compounds.

Resumen. Los hongos fitopatógenos pueden causar pérdidas económicas. La aplicación de productos naturales de especies del género Agave constituye una alternativa para el control de estos organismos. El objetivo del presente trabajo fue determinar el perfil fitoquímico de extractos de Agave angustifolia y A. cupreata, así como evaluar su actividad antifúngica contra varias especies de hongos fitopatógenos. Se obtuvo el extracto acuoso de las hojas de A. angustifolia y acetónico de A. cupreata. El perfil fitoquímico se determinó por cromatografía en capa fina y se evaluó la inhibición del crecimiento micelial y producción de esporas. El tamizaje reveló la presencia de alcaloides, flavonoides, saponinas y triterpenos. El extracto acetónico de A. cupreata inhibió el 76, 60 y 59% del crecimiento micelial de Lasiodiplodia viticola, Colletotrichum sp., y Epicoccum sorghinum respectivamente a 8 y 16 mg mL-1 (p≤0.05), mientras que el porcentaje de producción de esporas disminuyó 92 y 86 % (p≤0.001) para Fusarium subglutinans y Colletotrichum sp., respectivamente. El extracto acuoso de A. angustifolia inhibió 40% del crecimiento micelial de E. sorghinum a 16 mg mL-1 (p≤0.05) y disminuyó en 35% (p≤0.001) la producción de esporas de L. viticola. Los resultados indicaron que los extractos representan una alternativa para obtención de compuestos antifúngicos.

Abstract In Mexico, pigmented creole corn varieties are used for its consumption in a great diversity of foods. Purple corn has a high content of phytochemicals (health promoters). The extrusion process improved the accessibility of these phytochemicals. The aim of this work was to evaluate the effect of extrusion factors on the nutraceutical and functional properties of nixtamalized purple corn flour, and determine the optimal process conditions that allows obtaining a flour with the best characteristics to be used in the preparation of a beverage. The processing factors were temperature (T = 50-170 °C) and screw speed (SS = 50-240 rpm). The properties evaluated were total phenolic compounds (TPC), total anthocyanins (TA) antioxidant activity (AOX), and water solubility index (WSI). The optimization was carried out using the response surface methodology. The optimization yielded the following values: AOX: 676.34 µmol ET/100 g, TPC: 299.61 mg EGA/100 g, TA: 29.9 mg EC3G/100 g and WSI: 6.31%, under process conditions T = 50 °C and SS = 50 rpm. It was demonstrated that it is possible to generate a flour with the use of pigmented corn native to the state of Guerrero, with suitable properties for developed new corn based products.

Abstract Corn (Zea mays) is the most consumed cereal in México, so it is necessary to know the nutritional and anatomical quality of the grains, which have been the main conservation and consumption criteria of the prehispanic peoples. This practice has allowed to preserve varieties of Creole corn, however, due to the lack of knowledge of these characteristics the cultivation of these maize has been reduced, presenting a high risk of disappearing. The objective was to determine the physical, nutritive and functional quality of four varieties of creole corn: Purple-Olotillo, Dos-Puntas, Toro and Olotillo. Toro presented the highest values of width and thickness (10.79 and 7.71 mm). The Toro showed better values of Endosperm and Pericarp (84.25% and 4.01%), Dos-Puntas and Olotillo showed higher values of Germ (10.75%) and Pericarp (6.2%), respectively. The Toro had a higher content of Carbohydrates and Proteins (74.47 and 10.61%). In WSI, the best value was obtained by Dos-Puntas (11.91%) and WAI the Olotillo (245.56 g H2O/g sample). It is concluded that the Toro has better nutritional content and larger and weight grains, while the Olotillo presented the highest values of WAI, it can confer better technological properties for food processing.

Abstract In the tropics of Mexico, grasslands are the basis for feeding ruminants. The objective of the study was to determine the density, rate of appearance, death and survival of the population of stems of the Llanero grass (Andropogon gayanus Kunt) harvested at different regrowth ages (EA: 7.14, 21, 28, 35, 42 , 49 and 56 d), in two growth periods, dry season with irrigation and rainy season. The EA (treatments) were assigned to four experimental units of 3 m2, using a randomized complete block design, with four replications. In both growth periods, the stem density increased until the 28 days of regrowth later, decreased until the end of the study with greater intensity during the dry period with irrigation compared to the rainy season (325 and 378 stems m-2, respectively). There was greater appearance and death of stems in the dry period with irrigation (97 stems 100 stems-1 week-1). The population stability index was greater or close to one during the irrigated drought, while, in rains from the 42 days of regrowth, this was less than one. In conclusion, it was obtained that regrowth ages from 7 to 28 days do not compromise the population stability of stems and favor the persistence of the grasslands. Older regrowth ages during the rains do not allow to recover the stem population, which favors population instability.

Resumen En trópico de México las praderas con pastos constituyen la base de la alimentación de los rumiantes. El objetivo del estudio fue determinar la densidad, tasa de aparición, muerte y la sobrevivencia de la población de tallos del pasto Llanero (Andropogon gayanus Kunt) cosechado a diferentes edades de rebrote (ER: 7,14, 21, 28, 35, 42, 49 y 56 d), en dos periodos de crecimiento, época de sequía con riego y época de lluvias. Las ER (tratamientos) se asignaron a cuatro unidades experimentales de 3 m2, mediante un diseño de bloques completos al azar, con cuatro repeticiones. En ambos periodos de crecimiento, la densidad de tallos se incrementó hasta los 28 días de rebrote posteriormente, disminuyó hasta el final del estudio con mayor intensidad durante el periodo de sequía con riego respecto al de lluvias (325 y 378 tallos m-2, respectivamente). Hubo mayor aparición y muerte de tallos en el periodo de sequía con riego (97 a 100 tallos semana-1). El índice de estabilidad de la población fue mayor o próximo de uno durante la sequía con riego, mientras que, en lluvias a partir de los 42 días de rebrote, este fue menor que uno. En conclusión, se obtuvo que edades de rebrote de 7 a 28 días no se compromete la estabilidad poblacional de tallos y favorece la persistencia de las praderas. Mayores edades de rebrote durante las lluvias no permiten recuperar la población de tallos, lo que propicia inestabilidad de la población.

Abstract Corn (Zea mays L.) is the most consumed cereal in México and Latin America, it is important to know the physical quality of the cob and grain to obtain data that serve as a basis for the selection of the best varieties and with it contribute to the conservation and improvement of local varieties, which since the introduction of improved seeds have been at risk of disappearance due to their low yield and poor use. In the spring-summer cycle of 2018, in the town of Cruz Grande municipality of Florencio Villarreal, Guerrero. An experiment was established under a completely randomized block design. The objective was to determine the physical quality of grains and cobs of two genotypes of pigmented corn (red and yellow) belonging to the Dos Puntas variety. The quality of the cob and seed anatomy was evaluated. The results showed that there were no statistical differences between varieties; the grain with the best endosperm is yellow (80.82%) and germ is purple (11.61%); as well as, the yellow variety has a larger grain size (length 10.09 and width 4.31 mm). It is concluded that the corn with the best characteristics for sale as whole grain and use in the dough and tortilla industry, is yellow, and purple for oil extraction.

Resumen El maíz (Zea mays L.) es el cereal de más consumo en México y Latinoamérica, es importante conocer la calidad física de la mazorca y de grano a fin de obtener datos que sirvan como base para la selección de las mejores variedades y con ello contribuir a la conservación y mejora de variedades locales, que desde la introducción de semillas mejoradas se han visto en riesgo de desaparición por su bajo rendimiento y poco aprovechamiento. En el ciclo primavera-verano de 2018, en la localidad de Cruz Grande municipio de Florencio Villarreal, Guerrero. se estableció un experimento bajo un diseño en bloques completamente al azar. El objetivo fue determinar la calidad física de granos y mazorcas de dos genotipos de maíz pigmentado (rojo y amarillo) perteneciente a la variedad Dos Puntas. Se evaluó la calidad de la mazorca y anatomía de semillas. Los resultados mostraron que no hubo diferencias estadísticas entre variedades, el grano con mejor endospermo es el amarillo (80.82%) y germen es el morado (11.61%) así como, la variedad amarilla presenta un mayor tamaño de grano (largo 10.09 y ancho 4.31 mm). Se concluye que el maíz con las mejores características para venta como grano entero y para la utilización en la industria de la masa y tortilla, es el amarillo y el morado para extracción de aceite.

Abstract Agave angustifolia has a wide morphological variation, which often makes its taxonomy difficult. The differentiation between Agave species is made from homologous and independent morphological characteristics, whose variation can be ontogenetic and genetic. The objective of this research was to characterize the morphology of A. angustifolia called ‘sacatoro’ from the state of Guerrero. The research was conducted from 2016 to 2017, in six populations of A. angustifolia and two populations as control, A. angustifolia Haw and A. cupreata. 32 stem and leaf variables of mother plants and shoots were measured for each specimen, according to the technical guide for the varietal description of Agave spp. The data were analyzed using main components (ACP) and hierarchical agglomerative grouping (AJA). The variables that allowed to discern the populations were: shape, edge, color and texture of the leaf, striae on lateral spines and length of the terminal spine, all with a positive correlation. The results obtained from the ACP and the AJA allowed observing the relationship between variables and specimens based on the morphological attributes shared by the species studied. Despite the morphological variation between maguey sacatoro and A. angustifolia Haw, a close positive relationship between both is shown. So, it is inferred that the phenotypic characteristics that subgrouping the maguey sacatoro, could show as a result a possible variant of A. angustifolia Haw that would allow to locate taxonomically this group to contribute to the ordering of the Agave genus and its conservation.

Resumen El Agave angustifolia presenta una amplia variación morfológica, que con frecuencia dificulta su taxonomía. La diferenciación entre las especies de Agave, se hace a partir de características morfológicas homólogas e independientes entre sí, cuya variación puede ser ontogenética y genética. El objetivo de esta investigación fue caracterizar la morfología del A. angustifolia denominado ‘sacatoro’ del estado de Guerrero. La investigación se realizó de 2016 a 2017, en seis poblaciones de A. angustifolia y dos poblaciones como control, A. angustifolia Haw y A. cupreata. Se midieron 32 variables del tallo y hojas de plantas madre e hijuelos a cada ejemplar, de acuerdo con la guía técnica para la descripción varietal de Agave spp. Los datos se analizaron mediante componentes principales (ACP) y agrupamiento aglomerativo jerárquico (AJA). Las variables que permitieron discernir las poblaciones fueron: forma, borde, color y textura de la hoja, estrías en espinas laterales y longitud de la espina terminal, todas con una correlación positiva. Los resultados obtenidos del ACP y el AJA permitieron observar la relación entre variables y especímenes en función de los atributos morfológicos que comparten las especies estudiadas. A pesar de la variación morfológica entre el maguey sacatoro y el A. angustifolia Haw., se muestra una estrecha relación positiva entre ambos. Por lo que se infiere que las características fenotípicas que sub agrupan al maguey sacatoro, pudieran mostrar como resultado una posible variante de A. angustifolia Haw que permitiría ubicar taxonómicamente a este grupo para contribuir a la ordenación del género Agave y su conservación.

Abstract Mango powdery mildew (Erysiphe quercicola) causes up to 90% production losses, so it is necessary to estimate the tolerance to this pathogen of the new germplasm introduced or recently generated to increase the export potential of Mexico. The objective of this study was to determine the response to powdery mildew damage by means of an optimized inoculation technique to induce the disease in attached leaves of 10 new yellow mango cultivars for Mexico. Two inoculation methods were evaluated. The best was to spray conidia at 4.6 x 105 spores mL-1 on the adaxial and abaxial leaves surfaces, at ± 300-450 lux and suspended in polysorbate 20 + surfactant based on ethoxilate alcohols at 2%. The inoculation test showed that the cv. Alphonso was moderately tolerant and Neelum and Fairchild were slightly tolerant. In contrast, Nam Doc Mai, Rosigold, Ataulfo Zafiro, Cotaxtla and Kesar were susceptible and Mallika and Ivory were highly susceptible. The most tolerant cultivars had lower values of incidence, maximum severity, area under the disease progress curve, apparent infection rate and conidia density per cm2 of damaged leaf area (LSD, P≤0.05).

Resumen La cenicilla del mango (Erysiphe quercicola) causa pérdidas de producción de hasta 90%, por lo que es necesario estimar la tolerancia a este patógeno en el nuevo germoplasma introducido o generado recientemente para incrementar el potencial de exportación de México. El objetivo de este estudio fue determinar la respuesta al daño por cenicilla mediante una técnica de inoculación optimizada para inducir la enfermedad en hojas adheridas de 10 cultivares de mango amarillo nuevos para México. Se evaluaron dos métodos de inoculación. El mejor fue por aspersión de conidios a una concentración de 4.6 × 105 esporas mL-1, en las superficies adaxial y abaxial de las hojas, a ± 300 - 450 lux y suspendidos en polisorbato 20 + surfactante a base de alcoholes etoxilados al 2%. La prueba de inoculación mostró que el cv. Alphonso fue moderadamente tolerante y Neelum y Fairchild ligeramente tolerantes. En contraste, Nam Doc Mai, Rosigold, Ataúlfo Zafiro, Cotaxtla y Kesar fueron susceptibles y Mallika e Ivory altamente susceptibles. Los cultivares más tolerantes presentaron valores menores de incidencia, severidad máxima, área bajo la curva del progreso de la enfermedad, tasa de infección aparente y densidad de conidios por cm2 de área foliar dañada.

Resumo: O objetivo deste trabalho foi avaliar estratégias fitossanitárias para o controle químico do míldio-da-mangueira (Oidium mangiferae), baseadas na alternação de princípios ativos com diferentes modos e sítios de ação, e determinar as condições ambientais e epidemiológicas que favorecem o desenvolvimento da doença. O experimento foi realizado em Guerrero, México, em pomares comerciais, no âmbito de um programa para o desenvolvimento de estratégias de pulverização com fungicida. Curvas epidêmicas foram utilizadas em análises temporais da doença quanto à: incidência; área abaixo da curva de progresso da doença (AACPD); severidade; e sazonalidade dos conídios e sua relação com parâmetros meteorológicos. A doença foi mais bem controlada com a aplicação de fungicida sistêmico seguido de fungicida de contato, com atividade multissítio. Os primeiros sintomas apareceram 30 dias após a emissão dos brotos, e os estádios fenológicos mais sensíveis (críticos) foram o de floração completa e o de frutos com 8-15 mm. As condições ótimas para o desenvolvimento do oídio, que maximizam a densidade de esporos no ar, são temperatura acima de 30°C e umidade relativa superior a 90%.

Abstract: The objective of this work was to evaluate phytosanitary strategies for the chemical control of powdery mildew (Oidium mangiferae) in mango, based on the alternation of active ingredients with different modes and sites of action, and to determine the environmental and epidemiological conditions that favor the development of the disease. The experiment was conducted in Guerrero, México, in commercial orchards, within a program for the development of fungicide spraying strategies. Epidemic curves were used on temporal analyses of the disease for: incidence; area under disease progression curve (AUDPC); severity; and conidial seasonality and its relationships with meteorological parameters. The disease was better controlled with the application of systemic fungicide followed by contact fungicide with multisite activity. The first symptoms appeared 30 days after the issuance of shoots, and the most susceptible phenological (critical) stages were at full bloom and at the onset of fruit with 8-15 mm. Optimum conditions for the development of powdery mildew, which maximizes the density of airborne spores, are temperatures higher than 30°C and relative humidity over 90%.

Abstract: Physico-chemical and microbiological parameters were analyzed during dry and rainy season to verify the water quality of the lower Papagayo river basin and its tributaries. The analyzed parameters were compared with the Ecological Water Quality Criteria and Mexican Official Standards. Some values of the physico-chemical and microbiological analyses were outside of the maximum permissible levels in the rainy season (fecal coliforms, sedimentary solids, total suspended solids and turbidity), and which were significantly different with respect to dry season, whose values of the total hardness and dissolved oxygen increased in some sampling sites during this season. Metal concentrations showed values according to the official regulations, as well as the fats and oils. Physico-chemical and water quality of the Papagayo river basin show that Omitlán river was the station with the highest contamination level. Despite the considerable contributions of pollutants into the principal stream of the Papagayo river, in the two sampling stations located in the lower portion of the basin, termed Bellavista Papagayo and Lomas de Chapultepec, it is appreciated that the river has a good capacity of autopurification, even when in these localities there is an important contribution of pollutants. Based on the results obtained and the application of those rules, it was determined that the water in the downstream basin of the Papagayo river should not be used directly as a source of drinking water for the population centers. This is because they contain dangerous pollutants that cause adverse effects to humans.

Resumen: Se realizaron análisis físico-químicos y microbiológicos durante la temporada de secas y lluvias para conocer la calidad del agua de la cuenca baja del río Papagayo y sus afluentes. Los parámetros analizados se compararon con los criterios ecológicos de calidad del agua y las Normas Oficiales Mexicanas. Algunos valores de los análisis físico-químicos y microbiológicos se encuentran fuera de los límites máximos permisibles en la época de lluvias (coliformes fecales, sólidos sedimentables, sólidos suspendidos totales y turbiedad), los cuales difieren de forma significativa con respecto a la época de secas, la dureza total y el oxígeno disuelto aumentaron en algunos sitios de mu est reo. La concentración de metales, grasas y aceites presenta valores permitidos en las normas oficiales. La calidad fisicoquímica y microbiològica del agua de la cuenca del río Papagayo muestra que la estación con mayor grado de contaminación es la del río Omitlán. A pesar de los aportes considerables de materia contaminante al cauce principal del río Papagayo, en las estaciones de mu est reo Bellavista Papagayo y Lomas de Chapultepec, se aprecia que tiene capacidad de autopurificación, aun cuando en dichos puntos hay contribuciones importantes de contaminantes. Los resultados revelan que la cuenca baja del río Papagayo presenta contaminantes que causan efectos nocivos al ser humano, como la mayoría de los ríos en México, no puede considerarse como fuente de abastecimiento de agua potable.

The objective was to evaluate the activity against Haemonchus contortus by foliage taken from three tanniferous tree species and fed to Creole male kids experimentally infected with a dose of 350 larvae of H. contortus (L3) kg-1 body weight (BW). Twenty Creole kids weighing 12 ± 2.0 kg were randomly distributed in four treatments: T1 = control without foliage, and the addition of fresh foliage (10 % of the dry matter of the total diet) of Guazuma ulmifolia (T2), Pithecellobium dulce (T3) and Acacia cochliacantha (T4). For sixty days, the activity of the foliage against H. contortus was evaluated by quantifying the reduction in the excretion of eggs per gram of feces; also, the excretion of eggs was associated with the concentration of the blood cell pack, dry matter intake and weight change in animals. The data of the evaluated variables were analyzed in a completely randomized design and a Tukey test was carried out for comparison of means (p < 0.05). The secondary compounds of P. dulce and A. cochliacanta foliage were more effective (p < 0.04) in the control of H. contortus with minor excretion of eggs (1.48 and 1.18 Log10 g-1 of feces), respectively. The hematocrit was different (p < 0.005) mainly in hemoglobin, erythrocytes, lymphocytes and eosinophils; dry matter intake (p < 0.05) and changes in total body weight (p < 0.01) were higher in kids which received P. dulce foliage (T3) with 621.5 g d-1 and 2.4 kg, respectively. It was concluded that the secondary compounds of fresh P. dulce and A. cochliacantha foliage have the potential to control H. contortus without affecting the health and productive response in kids.

El objetivo fue evaluar la actividad contra Haemonchus contortus del follaje de tres árboles taniníferos en cabritos criollos infestados experimentalmente con una dosis de 350 larvas de H. contortus (L3) Kg-1 peso vivo. Veinte cabritos criollos de 12 ± 2.0 kg de peso vivo (PV), fueron distribuidos al azar en cuatro tratamientos: Tl= testigos sin follaje, y la adición de follaje fresco (10 % de la materia seca de la dieta total) de Guazuma ulmifolia (T2), Phitecellobium dulce (T3) y Acacia cochliacantha (T4). Durante 60 d se evaluó la actividad de los follajes contra H. contortus mediante la reducción en la excreción de huevos por gramo de heces (hpgh); además, la excreción de huevecillos se asoció con la concentración del paquete celular sanguíneo y el cambio de peso de los animales. Los datos de las variables evaluadas se analizaron en un diseño completamente al azar y la prueba de Tukey para la comparación de medias (p < 0.05). Los compuestos secundarios del follaje de P. dulce y A. cochliacanta resultaron más eficaces (p < 0.04) en el control de H. contortus, con menor excreción de hpgh (1.48 y 1.18 Log10 g-1 de heces), respectivamente. El hematocrito fue diferente (p < 0.005) principalmente en hemoglobina, eritrocitos, linfocitos y eosinófilos; el consumo de materia seca (p < 0.05) y el cambio de peso vivo total (p < 0.01) fue mayor en los cabritos que recibieron el follaje de P. dulce con 621.5 g d-1 y 2.4 kg de peso, respectivamente. Se concluye que los follajes de P. dulce y A. cochliacanta, por su contenido de taninos, tienen potencial para el control de H. contortus, lo que amerita mayor investigación.

Con el objetivo de evaluar si la transferencia de un embrión a cabras previamente servidas por monta natural conduce a un incremento de la prolifi cidad y la fertilidad, se llevó a cabo el presente estudio en el Colegio Superior Agropecuario del Estado de Guerrero, en Iguala, Gro., México a 18º 15´ LN con clima Aw0 (w) (i’) g. Los tratamientos evaluados fueron: Grupo MN + TE (n=14), cabras servidas por monta natural a las que se les transfirió un embrión en fresco el día 6 post-estro; Grupo TE (n=8), hembras a las que se les transfirieron en fresco dos embriones, y Grupo MN (n=16), cabras que fueron servidas por monta natural. Se utilizó un análisis de varianza y las pruebas de Ji Cuadrada y Exacta de Fisher. La tasa de fertilidad fue igual (P>0,05) entre los Grupos MN + TE (71,4%), TE (75.0%) y MN (81,2%); mientras que el índice de prolifi cidad de 2,2 ± 0,6 cabritos por hembra parida observado en el Grupo MN + TE, fue mayor (P<0,05) a los índices de 1,5 ± 0,5 y de 1,4 ± 0,5 crías por cabra parida registrados en los Grupos TE y MN, respectivamente, sin encontrarse diferencias (P>0,05) entre los dos últimos grupos evaluados. Se concluye que la transferencia de un embrión a cabras previamente servidas por monta natural tiene un efecto positivo sobre la prolificidad, sin que se afecte la fertilidad subsecuente.

In order to evaluate if one embryo transferred to goats previously served for natural mating lead to an increase in the prolificacy and the fertility, a study was carried out in the Colegio Superior Agropecuario del Estado de Guerrero, in Iguala, Gro., Mexico, at 18º 15´ N with Aw0 (w) (i’) g climate. The treatments evaluated were: NM + ET Group (n=14), goats served for natural mating that received one fresh embryo transferred 6 d later; ET Group (n=8), females that received two fresh embryos transferred; and NM Group (n=16), goats served for natural mating. Data were analyzed using the Chi-Square and Fisher tests and analysis of variance. Fertility rate was similar (P>0.05) among NM + ET (71.4%), ET (75.0%) and NM (81.2%) groups; whereas the prolificacy index of 2.2 ± 0.6 kids for doe kidding observed in the Group NM + ET was greater (P<0.05) that the prolificacy index of 1.5 ± 0.5 and 1.4 ± 0.5 kids for goat kidding registered for the ET and NM Groups, respectively; no difference was found (P>0.05) between these groups. We conclude that if one embryo is transferred to goats previously served for natural mating it has a positive effect on the prolificacy, without affecting the subsequent fertility.

Abstract The study was conducted in the village of Filo de Caballos, municipality of Leonardo Bravo, Guerrero, Mexico, from November 2011 to October 2012, in an orchard of Hass avocado, 5 years old. The objective was to evaluate the treatment of chemical and organic nutrition of avocado trees; fertilizers used were: 50 kg tree of cattle dung (manure); 200-100-200 kg ha-1 of N-P-K (edaphic) and 30-10-15.30 kg ha-1 of Ca-Mg-B (foliar). We found that in buds, treatment manure + edaphic + foliar (41 shoots/branch) was better than treatments manure + edaphic (19 shoots/branch), leaf (9 shoots/branch) and the control (21 shoots/branch). And with 17 fruits, manure + treatment + foliar edaphic significantly exceeded the edaphic + foliar treatments (6 fruits), leaf (1 fruit) and the control (3 fruits). The manure + foliar treatment had the highest length (16 cm) of the main shoot, beating the treatment of manure + edaphic (7 cm) and leaf (9 cm). The edaphic + foliar treatment (75 cm2) had higher leaf area than control (65 cm2) and had the highest fruit weight 2.62 kg with 10 fruits, which was significantly higher than the control (1.51 kg 10 fruits).

Resumen El estudio se realizó en la localidad de Filo de Caballos, municipio de Leonardo Bravo, Guerrero, México, durante noviembre de 2011 a octubre de 2012 en un huerto de aguacate Hass, de 5 años de edad. El objetivo fue evaluar tratamientos de nutrición química y orgánica en árboles de aguacate; los abonos usados fueron: estiércol bovino 50 kg árbol (estiercol); 200-100-200 kg ha-1 de N-P-K (edáfico) y 30-10-15 kg ha-1 de Ca-Mg-B (foliar). Se encontró que en brotes florales, el tratamiento estiércol + edáfico + foliar (41 brotes/rama) fue mejor que los tratamientos estiércol + edáfico (19 brotes/rama), foliar (9 brotes/rama) y el testigo (21 brotes/rama). Además, con 17 frutos, el tratamiento estiércol + edáfico + foliar superó de manera significativa a los tratamientos de Edáfico + foliar (6 frutos), foliar (1 fruto) y al testigo (3 frutos). El tratamiento de estiércol + foliar tuvo la mayor longitud (16 cm) del brote principal, superando a los tratamientos de estiércol + edáfico (7 cm) y foliar (9 cm). El tratamiento edáfico + foliar (75 cm2) presentó mayor área foliar que el testigo (65 cm2) y tuvo el mayor peso de fruto con 2.62 kg 10 frutos, el cual fue significativamente mayor que el testigo (1.51 kg 10 frutos).

Agronomic traits and genetic components are indicators of quality; additional factors are important to study the traits of germplasm in a breeding program. The effects of general (GCA) and specific (SCA) combining adequacy and the type of gene action for agronomic traits of regular maize (Zea mays L.) seeds and high-quality protein were analysed. The genetic material consisted of 10 maize inbred lines: four of regular grain and six high-quality protein. The variables analysed were: days to male and female flowering, plant and ear height, plant and ear score, and grain yield. The results showed significant variation among genotypes (p≤ 0.01) on the effects of GCA and SCA for all agronomic variables. Lines were identified as: T-44, B-41, LT-155, T-45 and CML-144 C, with higher values of GCA, being 0.6379, 0.4592, 0.3286, 0.2945 and 0.3382 t ha-1, respectively, for grain yield. Furthermore, outstanding materials based on its identified SCA crosses 4 * 8 (B-41 * CML-144), 1 * 5 (T-45 * CLQ-6203), and 2 * 7 (T-44 * CML- 142), with SCA estimated values for grain yield of 1.0875, 0.9544 and 0.7591 t ha-1, respectively. The type of additive gene action was the predominant in agronomic characters.

Los caracteres agronómicos y sus componentes genéticos son indicadores de la calidad de semillas; además, son factores importantes para estudiar las características del germoplasma en un programa de mejoramiento. Se analizaron los efectos de aptitud combinatoria general (ACG) y específica (ACE) y el tipo de acción génica de caracteres agronómicos de la semilla de maíz (Zea mays L.) normal y de alta calidad de proteína. El material genético consistió de 10 líneas endogámicas de maíz: cuatro de grano normal y seis de alta calidad de proteína. Se analizaron las variables: días a floración masculina y femenina, altura de planta y mazorca, calificación de planta y mazorca, y rendimiento de grano. Los resultados mostraron variación significativa entre genotipos (p≤ 0.01) en los efectos de ACG y ACE para todas las variables agronómicas. Se identificaron líneas como: T-44, B-41, LT-155, T-45 y CML-144 C, con valores mayores de ACG, siendo 0.6379, 0.4592, 0.3286, 0.2945 y 0.3382 t ha-1, respectivamente, para rendimiento de grano. Además, se identificaron materiales sobresalientes con base a su ACE las cruzas 4 * 8 (B-41 * CML-144), 1 * 5 (T-45 * CLQ-6203), y 2 * 7 (T-44 * CML-142), con valores estimados de ACE para rendimiento de grano de 1.0875, 0.9544 y 0.7591 t ha-1, respectivamente. El tipo de acción génica aditiva fue la que predominó en los caracteres agronómicos.

Mexican agriculturists have recently noticed strong increases of mite infestations in papaya (Carica papaya L. 1753) orchards. A list of mite species associated with papaya leaves was constructed to determine the species responsible for high infestations and to identify predaceous mites as potential biological control agents. Mites were collected from three foliage strata (high, middle and low), in seven municipalities of central Veracruz State. Leaves were processed by washing and sieving. Identified species included four tetranychids: Eotetranychus lewisi (McGregor 1943), Eutetranychus banksi (McGregor 1914), Tetranychus merganser Boudreaux 1954, and Tetranychus urticae Koch 1836; as well as three phytoseiids: Euseius hibisci (Chant 1959), Galendromus helveolus (Chant 1959) and Phytoseiulus macropilis (Banks 1905), with the first two species being the most abundant. The vagrant eriophyid Calacarus citrifolii Keifer 1955 was collected in three municipalities, in the low stratum. Neither the broad mite, Polyphagotarsonemus latus (Banks 1904), nor the carmine spider mite, Tetranychus cinnabarinus (Boisduval 1867), were collected, although these species were previously recorded from this area. None of the Phytoseiid species found can be considered a recently established species; their potential as biological control agents is discussed.

Productores agrícolas en México recientemente notaron un fuerte incremento en las infestaciones de ácaros en las huertas de papayo (Carica papaya L. 1753). Se elaboró una lista de las especies de ácaros asociados con hojas de papayo para determinar las especies responsables de las altas infestaciones y para identificar a los ácaros depredadores. Los ácaros fueron colectados de tres estratos (alto, medio y bajo) en siete muncipios del centro del estado de Veracruz. Las hojas fueron procesadas por lavado y tamizado. Las especies identificadas incluyeron cuatro tetraníquidos: Eotetranychus lewisi (McGregor 1943), Eutetranychus banksi (McGregor 1914), Tetranychus merganser Boudreaux 1954 y Tetranychus urticae Koch 1836; tres fitoseidos: Euseius hibisci (Chant 1959), Galendromus helveolus (Chant 1959) y Phytoseiulus macropilis (Banks 1904), donde las dos primeras especies fueron las más abundantes. El ácaro eriófido errante Calacarus citrifolii Keifer 1955 fue colectado en tres municipios, en el estrato bajo. El ácaro blanco, Polyphagotarsonemus latus (Banks 1904), y el ácaro carmín, Tetranychus cinnabarinus (Boisduval 1867), no fueron colectados, aunque estas dos especies fueron registradas previamente en esta área. Ninguno de los fitoseidos encontrados puede ser considerado de reciente establecimiento en el área; se discute su potencial como agentes de control biológico.

The temporal progress of anthracnose (Colletotrichum gloeosporioides) epidemics was studied in mango (Mangifera indica) orchards treated with fungicides from different chemical groups, mode of action, and application sequences in two regions of contrasting climates (sub-humid and dry tropics) in Guerrero, Mexico. Full flowering, initial setting, and 8-15mm Ø fruits were identified as critical stages for infection. Epidemics started 20-26 days after swollen buds, and maximum severity was attained at 40-42 days after the first symptoms were detected. The Weibull model described (r²>0.89) anthracnose epidemics in both floral and vegetative flushes. Active ingredients of different fungicide groups, mode of action, and residuality such as myclobutanil, azoxystrobin, cyprodinil+fludioxonil, quinoxyfen, and chlorotalonil + sulfur led to significantly low values (LSD<0.05%) in the Yf, AUDPC and b-1 parameters. The best strategy was to initiate a preventive treatment with a systemic ingredient, independently of its chemical group. Severity of the disease in floral (Fl) and vegetative flushing (Veg) in the sub-humid tropic was related with temperature >30ºC (rFl=0.79-0.86; rVeg=0.80-0.95) and relative humidity > 90% (rFl=0.66-0.86; rVeg=0.67-0.94). In both regions, conidial sporulation was related to temperature >30ºC (r=0.72-0.74), relative humidity <60% (r=0.66), severity (rFl=0.62-0.98; rVeg=0.75-0.97) and dew point <25ºC (r=0.68-0.69).