RESUMO A China lidera a mudança global da matriz energética e o faz principalmente na América Latina. Essa mudança questiona a posição e a liderança dos Estados Unidos em geral e, particularmente, na América Latina. As evidências mostram que os Estados Unidos estão atrasados na mudança energética em termos técnicos e institucionais e estão fortemente ancorados na energia suja. As evidências também mostram que os EUA não estão permitindo o avanço da China na região facilmente. A geração de energia a partir de fontes de energia limpa está em ascensão, com a China liderando em equipamentos solares e barragens hidrelétricas, enquanto compra redes de distribuição elétrica de empresas norte-americanas. As consequências para a economia global serão sentidas em muitas frentes, desde a mudança no sinal da balança comercial e diminuição da inflação até realinhamentos de moeda e remodelação do poder com o colapso dos preços do petróleo.

ABSTRACT China is leading the global change in the energy matrix and mainly Latin America. This change questions the position and leadership of the United States in general and particularly in Latin America. Evidence shows that the United States lags in energy change in technical and institutional terms and is anchored heavily in dirty energy. Evidence also indicates that the US is not allowing China to advance in the region quickly. Power generation from renewable energy sources is rising, with China leading in solar equipment and hydroelectric dams while buying out electric distribution networks from US firms. The consequences for the global economy will be felt on many fronts, from the balance of trade sign change and decreased inflation to currency realignments and power reshuffle as oil prices collapse.

Significant economic and ecological damage in corn-producing regions is caused by S. reilianum in the Highlands of the state of Mexico. Knowledge of the disease distribution and temporal spatial stability is essential for the development of integrated pest management programs. The present study is aimed to determine the S. reilianum temporal space stability and temporal spatial distribution from 2006 to 2009 in the state of Mexico. The disease incidence was determined in 100 maize plots at the town of Metepec, having them geographically located by means of a DGPS device. Determination of the temporal spatial distribution was performed using classical and temporal spatial statistics (SADIE and geostatistical). Aggregation maps were elaborated and the long term temporal space stability was determined with the Crámer-von Mises tests and the SADIE association index. As revealed by the results, inconsistency in determining the temporal spatial distribution of the disease was indicated by classical statistics, while the spatial statistics were able to establish the temporal spatial distribution type, being visualized through the elaborated maps. The space temporal stability was established for the years 2006, 2007 and 2009.

S. reilianum causa daños económicos y ecológicos importantes en regiones productoras de maíz en los Valles Altos de México. El conocimiento de la distribución y estabilidad espacio temporal de la enfermedad es indispensable para la elaboración de programas de manejo integrado. El presente estudio se realizó para determinar la estabilidad espacio temporal de la distribución espacial de S. reilianum durante los años 2006 a 2009 en el estado de México. La incidencia de la enfermedad se determinó en 100 parcelas de maíz de la localidad de Metepec, ubicándolas geográficamente con un DGPS. La determinación de la distribución espacial se realizó con el uso de la estadística clásica y espacial (SADIE y geoestadístico). Se elaboraron mapas de agregación y se determinó la estabilidad espacio temporal a largo plazo con las pruebas de Crámer-von Mises y con el índice de asociación del SADIE. Los resultados mostraron que la estadística clásica indicó inconsistencia en la determinación de la distribución espacial de la enfermedad mientras que con la estadística espacial se logró establecer el tipo de la distribución espacial que presentó visualizándose a través de los mapas elaborados. La estabilidad espacio temporal se logró establecer para los años 2006, 2007 y 2009.

A maize disease of unknown etiology appeared in the state of Veracruz, Mexico, during 2003-2004. Diseased plants were characterized by premature death, proliferation and poor ear growth, sterility in both male and female flowers, stalk rot, leaves with white spots, yellowing and reddening on leaf margins, leaf stripes, and necrosis. Maize Bushy Stunt (MBS) phytoplasma was PCR detected and associated with plants with yellow and red leaves and ear proliferation in Tlalixcoyan, Cosoleacaque and Paso de Ovejas counties in 2006 and 2007. Ten maize genotypes were evaluated for incidence and severity of the disease and grain yield performance in an experimental plot in Tlalixcoyan, Ver. in 2007. MBS was PCR detected in CP-562, 30F83, 30F92, Orca, 30F96, Nutria and Asgrow 7573; whereas Pioneer 3086, 30F97 y CP-560 were MBS negative. Highest incidence and severity was detected in 30F83 (27 %, 0.29), AS-7573 (21 %, 0.14) and 30F97 (21 %, 0.15). Best grain yield was produced by AS-7573 (5.4 ton ha-1), Orca (4.7 ton ha-1), and 30F97 (4 ton ha-1). Positive correlation was obtained between incidence and severity of the disease (r=0.69**), incidence and number of symptomatic ears (r=0.43**) and severity with decrease in weight of healthy grain (r=0.51**). There was no correlation between disease and yield.

Una enfermedad del maíz de etiología desconocida apareció epidémicamente en el estado de Veracruz, México durante 2003-2004. Las plantas enfermas se caracterizaron por muerte prematura de plantas, producción múltiple de jilotes estériles, pudrición vascular, hojas con manchas blancas, amarillamiento, enrojecimiento y franjeado foliar y necrosis. El fitoplasma Maize bushy stunt (MBS) se detectó por PCR asociado a plantas con amarillamiento, enrojecimiento foliar y proliferación de jilotes en los municipios de Tlalixcoyan, Cosoleacaque y Paso de Ovejas en 2006 y 2007. La incidencia, severidad y rendimiento se evaluaron en diez genotipos de maíz en una plantación experimental en Tlalixcoyan, Ver. en 2007. MBS se detectó por PCR en CP-562, 30F83, 30F92, Orca, 30F96, Nutria y Asgrow 7573, mientras que Pioneer 3086, 30F97 y CP-560 resultaron negativos. La mayor incidencia se presentó en los genotipos 30F83 (27%), AS7573 (21%) y 30F97 (21%) con una severidad de 0.29, 0.14 y 0.15, respectivamente. Los genotipos con mayor rendimiento de grano fueron AS-7573 (5.4 ton ha-1), Orca (4.7 ton ha-1) y 30F97 (4.0 ton ha-1). Hubo correlación positiva de la incidencia con la severidad de la enfermedad (r=0.69**), pero no de la enfermedad con el rendimiento.

Abstract Gray leaf spot of maize (Zea mays L.), caused by the fungus Cercospora zeae maydis Tehon & Daniels, has become an economically important disease in tropical humid maize growing areas of the Republic of Colombia. To implement an adequate program of selection and improvement of genetic tolerance to this disease, it was necesary to determine the inheritance of this tolerance. For this purpose, five highly tolerant and five-susceptible maize inbred lines were evaluated using a diallel design (Griffing Model 1), at the Centro Internacional de Agricultura Tropical (CIAT), Colombia. Parental lines and their crosses, both direct and reciprocal, were evaluated in three different environments using conservation tillage and were artificially inoculated using a mixture of gray leaf spot infected leaves collected from farmers’ fields. The variable Disease Index (DI; scale 1: resistant; 5: highly susceptible) of the parental lines and their direct and reciprocal crosses was determined in three environments, in fields planted under direct planting, artificially inoculated with inoculum prepared using leaves with symptoms of the disease collected from farmers’ fields. In the combined analysis, there were highly significant differences for parents, crosses (direct and reciprocal), general combining ability (GCA) and specific combining ability (SCA). There were no significant differences for either parents vs. crosses or for direct vs. reciprocal crosses. Consequently, heterosis was not important in DI (mean for parents: 2.97, and for crosses: 3.03) and no maternal effects were observed for these lines (mean for direct and reciprocal crosses: 3.03). GCA sum of squares (SS) was three fold of the SCA SS, meaning that additive gene effects were more important than non-additive gene effects. No parent×environment interaction was observed. Interaction of environment with crosses, GCA, and SCA were highly significant.

Resumen La mancha gris de la hoja o Cercoporosis del maíz (Zea mays L.), causada por el hongo Cercospora zeae maydis Tehon y Daniels, se ha convertido en una enfermedad de importancia económica en regiones del trópico húmedo productoras de maíz en la República de Colombia. Para implementar un programa adecuado de selección y mejoramiento de tolerancia genética a esta enfermedad fue necesario determinar la herencia de esa tolerancia. Para ésto, cinco líneas endogámicas muy tolerantes y cinco susceptibles a la enfermedad se evaluaron usando un diseño dialélico (Griffing Modelo I), en el Centro Internacional de Agricultura Tropical (CIAT), Colombia. La variable Índice de Enfermedad (IE; escala 1=tolerante; 5=susceptible) de las líneas progenitoras y sus cruzas directas y recíprocas se determinó en tres ambientes, en lotes de siembra directa e inoculadas artificialmente con inóculo de hojas con síntomas de la enfermedad recolectadas en campos de agricultores. En el análisis combinado, hubo diferencias altamente significativas para los progenitores, cruzas directas y recíprocas, aptitud combinatoria general (ACG) y aptitud combinatoria específica (ACE). No hubo diferencias significativas para progenitores vs cruzas ni para cruzas directas vs recíprocas. Consecuentemente, la heterosis no fue importante en el IE (media de los progenitores: 2.97 y para cruzas: 3.03) y no se observaron efectos maternos para estas líneas (media de cruzas directas y recíprocas: 3.03). La suma de cuadrados (SC) para ACG fue tres veces mayor que la SC de ACE; es decir, los efectos aditivos fueron más importantes que los no aditivos. No se observó interacción de progenitores×ambiente. La interacción de ambientes con cruzas, ACG y ACE fue altamente significativa.