Person: Dubin, H.J.
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Dubin, H.J.
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- Informe sinóptico de cinco años de observación del Ensayo Latinoamericano de Royas de Cereales (ELAR): 1979-1983 = Summary report of the Latin America Rust Trial(CIMMYT, 1990) Dubin, H.J.; Torres Ramirez, E.A.La Oficina Regional del CIMMYT (Trigo) para la Zona Andina con sede en Quito, Ecuador, creó en 1977 un vivero para estudiar el comportamiento de las royas del trigo y la cebada en las zonas productoras de América Latina. Este vivero fue llamado ENSAVO LATINO AMERICANO DE ROYA (ELAR). Al crear y diseñar el ELAR, se tuvo como modelo el Vivero Trampa del CIMMYT para el Medio Orienta (RDTN) diseñado por J.M. Prescott y E.E. Saari. El ELAR se distribuyó desde Quito, con la colaboración de los Programas Nacionales de la región, de 1978 a 1983. En 1984 se tomó la decisión de fusionar este vivero con el RDTN en una versión global conocida como "International Disease Trap Nursery" (IDTN). El ELAR buscó (1) determinar el espectro de virulencia de las poblaciones de roya en trigo y cebada a escala continental, así como sus variaciones locales y de un año a otro, y (2) valorar los niveles de desarrollo de cada una de las royas en las diferentes regiones. Con estos dos parámetros básicos, se pretende ir delineando los contornos de las posibles unidades epidemiológicas (o geopatológicas) de la región, para que este conocimiento permita medir el riesgo de epidemias de royas en un determinado lugar, y establecer bases racionales para la distribución de variedades. Los datos que se han tabulado en este informe provienen de los últimos cinco arios de vida del ELAR (1979 a 1983). En ese período, el ELAR se sembró desde el Noroeste de México hasta el sur de Brasil y Chile, y los niveles de desarrollo de las diferentes royas fluctuaron ampliamente. Es evidente que estos cinco arios no fueron suficientes para cumplir con los objetivos del ELAR, y que será preciso continuar con esta clase de investigación, tanto a escala continental como regional, nacional y local: lo continental porque las esporas acarreadas por el viento no respetan fronteras; lo nacional y local por la especificidad de las poblaciones de las royas, o sea, por la división de las vastas áreas cerealeras en unidades epidemiológicas discretas. El ejercicio de observar y estudiar las poblaciones de las royas, o de otros fitopatógenos, es parte integral del enfoque interdisciplinario para el mejoramiento genético. Por esta razón, el ELAR contenla un numero de variedades comerciales y de líneas avanzadas de cada uno de los países participantes. Al poner a prueba estos materiales bajo condiciones epidemiológicas tan diversas, ha sido posible dar cuenta del grado de estabilidad de su resistencia, y se ha medido simultáneamente la otra cara de la moneda, o sea, la variabilidad de las poblaciones de las royas. Al poner este informe en manos de sus legítimos autores, los Colaboradores de los programas nacionales, queremos resaltar la necesidad de fortalecer estos estudios con miras a establecer bases s61idas al manejo de las royas de los cereales en América Latina. Análisis preliminares de los datos de los ELAR fueron presentados en la reunión sobre las royas celebrada en Castelar, Argentina. Nos es grato agradecer a los científicos e instituciones qua colaboraron en el diseño, difusión y análisis inicial de los datos: el Dr. A. Klatt (uno de los iniciadores del ELAR), Ing. P. Kempmeijer (IPO) y el Programa de Cereales del Ecuador (INIAP). El Ing. A. Stubbs proporcion6 semilla de las diferenciales de Puccinia striiformis e identificó las razas. Mientras existió el ELAR, el Proyecto de Trigo Zona Andina fue parcialmente financiado por el CIDA. Una lista de los colaboradores se presenta en el Cuadro 1. Sin su interés y cooperación no hubiera sido posible el ELAR. Sea esta la ocasi6n para agradecer al Dr. Admasu Melakeberhan, postdoctorado en el Programa de Trigo del CIMMYT entre 1987 y 1988, y a la lngeniero Rosa Maria L6pez Atilano, del subprograma de Protección Vegetal (Trigo) del CIMMYT por su ayuda en la tabulaci6n manual de los datos analizados en este informe. Los procedimientos de análisis fueron desarrollados en parte por H.C. Young. A. McNab y E.P. Hettel editaron y formaron la publicación.
Publication - Cereal disease methodology manual(CIMMYT, 1986) Stubbs, R.W.; Prescott, J.M.; Saari, E.E.; Dubin, H.J.Beginning in 1976, the Research Institute for Plant Protection and CIMMYT initiated the Regional Workshops in Cereal Disease Methodology to develop or strengthen plant pathology research activities in national wheat improvement programs in developing countries. This manual is an outgrowth of the workshop series and presents the principal topics developed in the workshops, including production, origin, morphology, growth habit, diseases and disease development, surveying, resistant varieties, etc., for cereal grains. Characteristics of wheat and barley diseases are also included
Publication - Manuel des maladies: des ravageurs et des accidents communs du ble(CIMMYT, 1977) Christensen, C.M.; Dubin, H.J.; Fuentes, J.M.; Prescott, J.M.; Saari, E.E.L'objectif vise par ce fascicule est de faciliter l'identification des maladies, des ravageurs et des accidents du ble par les chercheurs, les vulgarisateurs et les producteurs de ble. Aucune mesure specifique de lutte n'est suggeree parce que ces moyens sont susceptibles d'etre differents d'un pays a l'autre. Les phytopathologistes et les entomologistes qui sont sur place devront Gtre consultes pour I 'identification des maladies et des ravageurs, ainsi que pour les mesures specifiques de lutte a utiliser.
Publication - Manual de campo: enfermedades y plagas comunes del trigo(CIMMYT, 1977) Christensen, C.M.; Dubin, H.J.; Fuentes Fuentes, S.; Prescott, J.M.; Saari, E.E.El propósito del manual es el de ayudar a los técnicos agrícolas que trabajan en el campo a identificar las enfermedades y plagas comunes del trigo. No se dan aquí procedimientos específicos de control químico, puesto que estos pueden diferir de un país a otro. Se sugiere que se consulte a los fitopat61ogos y entomólogos locales en lo que atañe a las medidas específicas de control.
Publication - Field manual of common wheat diseases and pests(CIMMYT, 1977) Christensen, C.M.; Dubin, H.J.; Fuentes Fuentes, S.; Prescott, J.M.; Saari, E.E.The purpose of this manual is to help agricultural field workers identify common diseases and pests of wheat. Specific chemical control procedures are not given since these may differ from country to country. Local plant pathologists and entomologists should be consulted concerning disease and pest identification as well as for specific control measures.
Publication - Manual de metodología sobre las enfermedades de los cereales(CIMMYT, 1986) Stubbs, R.W.; Prescott, J.M.; Saari, E.E.; Dubin, H.J.Suman 27 los países del mundo en desarrollo que cultivan más de 100,000 hectáreas de trigo cada uno y que destinan más del 95% de su producción al consumo humano directo. Aun cuando los rendimientos promedio y la producción total ha mostrado incrementos sustanciales en años recientes, las enfermedades del trigo son una de las principales causas, año con año, de la inestabilidad de los rendimientos en los países en desarrollo. Los organismos patógenos más importantes de las enfermedades del trigo son parásitos obligados que pueden convertirse en nuevas formas virulentas capaces de atacar a variedades que antes fueron resistentes. Para evitar este peligro, fitopatólogos y fitomejoradores deben trabajar juntos para producir en forma continua nuevas variedades resistentes a las razas patógenas predominantes. Desafortunadamente, en muchos países no se han establecido lazos fuertes entre los que practican estas dos disciplinas. Aun más, ha existido la tendencia por parte de los fitopatológos a realizar una investigación más básica en vez de aplicar las técnicas de campo recién desarrolladas para causar epifitias y seleccionar materiales de fitomejoramiento. En 1976, el Instituto de Investigación para la Protección Vegetal (IPO) de Wageningen, Países Bajos, y el Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT) de México iniciaron los Talleres Regionales sobre la Metodología de Enfermedades de Cereales para establecer o fortalecer las actividades de investigación fitopatológica en programas nacionales de mejoramiento del trigo en países en desarrollo. Estos talleres por lo general duran dos semanas que se han llevado a cabo semanas que se han llevado a cabo en 11 lugares de todo el mundo. Alrededor de 290 científicos de 40 países en desarrollo han participado en los talleres. Este manual, resultado de dichas actividades, presenta los temas principales que se trataron. Se espera que será ampliamente leído y consultado no sólo por los futuros participantes en los talleres, sino también por otros fitopatólogos de países en desarrollo. Mediante el repaso conciso de principios, así como también una clara descripción de las metodologías apropiadas a la investigación en países en desarrollo, esta obra promoverá la aplicación práctica de la fitopatología en programas de mejoramiento de trigo y otros cereales de grano pequeño.
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Postulated genes for resistance to stripe rust in selected CIMMYT and related wheats(American Phytopathological Society (APS), 1989) Dubin, H.J.; Johnson, R.; Stubbs, R.W.Infection type data were used to postulate the presence of stripe rust seedling resistance genes in 20 CIMMYT and related bread wheats. Yr3, Yr6, Yr7, and Yr9 were hypothesized to be present in 12 lines, either alone or in combination. The isolates used also indicated the presence of additional unknown seedling resistance genes. Four lines produced only low seedling infection types. Four other lines displayed adult plant resistance.Publication - Estimating the economic impact of breeding nonspecific resistance to leaf rust in modern bread wheat(American Phytopathological Society (APS), 1998) Smale, M.; Singh, R.P.; Sayre, K.D.; Pingali, P.L.; Rajaram, S.; Dubin, H.J.Breeding for resistance to rust diseases in wheat is an example of productivity maintenance research. Productivity maintenance research is necessary to avoid contractions in the wheat supply curve that result from changes in the biological or physical environment. In this study, the benefits of incorporating nonspecific resistance to leaf rust caused by Puccinia recondita into modern bread wheats (Triticum aestivum) have been estimated using data on resistance genes identified in cultivars, trial data, and area sown to cltivar in the Yaqui Valley, Sonora State, Mexico. In the most pessimistic scenario, the gross benefits generated in the Yaqui Valley from 1970 to 1990 were 17 million U.S. dollars (in 1994 real terms). Even when costs were overstated and benefits were understated, the internal rate of return on capital invested was 13%, well within the range recommended for use in project evaluation by the World Bank. Substantial economic benefits likely are associated with development of nonspecific resistance in many wheat-producing areas of developing countries where farmers change cultivars slowly because of delays in cultivar release, incomplete seed markets, and economic factors related to adoption or where disease pressure is heavy and the costs of treating disease outbreaks is high.
Publication - Helminthosporium blights of wheat: spot blotch and tan spot. Proceedings of an international workshop held at CIMMYT(UCL, 1998) Duveiller, E.; Dubin, H.J.; Reeves, J.; McNab, A.Over the last 30 ye~rs, in developing countries, the outstanding advances in wheat productivity attained by CIMMYT and its partners have contributed greatly to the well-being of millions of people. As growing numbers of farmers have taken advantage of new, superior wheat varieties, wheat has been introduced into warmer areas where it was not previously planted or has been grown in increasingly complex, intensive farming systems in the developing world's traditional wheat growing areas. These changing circumstances for wheat production have brought new challenges for farmers, including the increased incidence of helminthosporium blights of wheat: spot blotch, caused by Bipolaris sorokiniana, and tan spot, caused by Pyrenophora tritici-repentis. In South Asia's intensive rice-wheat cropping systems, particularly in the heavily populated eastern Gangetic Plains, spot blotch has become the major disease constraint. In reduced tillage cropping systems, tan spot is an increasingly important concern, as the pathogen survives on crop residues and alternate hosts. To complicate matters, these diseases may occur together in the field, where they are often very difficult to distinguish from one another. For this reason,-it is desirable to study their incidence and control together. The complexity of these nontraditional wheat diseases and of the conditions in which they occur makes it essential for us to seek a holistic approach for their control. Such an approach includes breeding for durable disease resistance; developing appropriate crop management practices, including nutrient applications; monitoring pathogen diversity; and applying recent advances in biotechnology to overcome disease losses. In addition, researchers need to develop a better understanding of the cropping systems and the many interactions that can influence the spread of disease. Better protocols for ensuring the production of healthy seed are needed as well. To strengthen research partnerships directed at reducing yield losses to these diseases, and to foster a more holistic view of potential strategies for disease control, CIMMYT organized an international workshop, Helminthosporium Blights of Wheat, at its headquarters in Mexico from 9 to 14 February, 1997. Sponsored by the Belgian Administration for Development Cooperation and CIMMYT, in close collaboration with the University of Louvain, Belgium, this workshop was an important component of a larger,- collaborative research project on nonspecific foliar pathogens of wheat. The meeting assembled key researchers from the national agricultural research systems of developed and developing nations to review recent advances in pathology and breeding for resistance to spot blotch and tan spot of wheat. Fifty-fo~ participants from 21 countries attended the workshop; participants represented most of the wheat-growing areas where tan spot and spot blotch limit yields. The workshop enabled researchers to bring each other up to date on the global incidence of foliar blights caused by B. sorokiniana and P. tritici-repentis, particularly in South Asia's ricewheat system and under reduced tillage. Research results were presented and discussed, future research collaborations defined, and networking activities strengthened, all with the goal of obtaining better disease control. This proceedings documents the results of a unique opportunity for CIMMYT scientists and their colleagues to exchange information on these two important diseases. The papers and workshop discussions presented here should provide a useful record for workshop participants. The proceedings also should prove to be a valuable reference for scientists who could not attend these meetings, researchers who work to reduce grain losses in the warmer production areas of developing countries, and their counterparts in.other parts of the world.
Publication - Fusarium head scab: global status and future prospects(CIMMYT, 1997) Dubin, H.J.; Gilchrist-Saavedra, L.; McNab, A.Fusarium head scab of wheat was first reported in England around 1884; however, scab is generally more important in warm and humid areas. The various fusaria that cause scab are among the most variable and insidious fungi. Scab can cause significant yield and quality damage as well as toxicoses in animals and humans. Concerns about toxin-related illnesses caused by fusarium in animals and humans have increased in recent years. Part of the reason is the increase in the incidence of fusarium head scab in several areas of the world, namely, the United States and several countries in Europe. Its increase appears to be principally related to changes in weather and cropping patterns. Damage due to scab in the USA was estimated at more than one billion dollars in 1993 and 500 million in 1994. Epidemics in China are most common and severe in the Yangtze River Valley, and can affect more than 7 million hectares of wheat. It is estimated that in China up to 2.5 million tons of grain may be lost to scab in epidemic years. Diseases related to fusarial mycotoxins in humans have been reported in China, India, and Japan, whereas in animals they have been reported in numerous parts of the world. CIMMYT has been working to control this disease in wheat and maize for many years due to its importance in countries such as Argentina, Brazil, China, Paraguay, and Uruguay. Breeding for resistance in wheat over the last 15 years has only been partially successful due to the difficulty of incorporating sufficient levels of resistance. The progress that has been made owes a great deal to the shuttle breeding program between CIMMYT and China. As part of its efforts to control scab of wheat, CIMMYT sponsored two previous workshops related to scab control and the effects of Fusarium toxins. One was held in Uruguay in 1987 and focused on the control of scab, and the other in Mexico in 1989 and dealt with mycotoxins. To date, international funds to achieve control of fusarium scab have been modest in relation to its impact on health, grain yield, and quality. Due to this and its increase in many areas, it was thought overdue to organize a worldwide workshop with the following objectives: To obtain an update on the global situation of small grains scab and its impact on food-feed production and health; • To document relevant research and increase communication among researchers; To search for funds to increase research on sustainable control methods. The workshop was supported by CIMMYT and by the generosity of the government of Austria, specifically the Institute of Agrobiotechnology, Tulln. Participants came from Argentina, Austria, Canada, China, Hungary, Japan, Mexico, Russia, UK, Ukraine, Uruguay, USA, and CIMMYT, Mexico. It is hoped that the results of this workshop, and the integration of scientists' efforts worldwide, will focus attention on this disease, provide new data, and increase the support necessary to achieve economical and environmentally safe control.
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