... Guerrero, Armando Espín, Luis Espín, Enrique Llugcha, Nancy Llugcha, Segundo Muyulema, Cesar ... more ... Guerrero, Armando Espín, Luis Espín, Enrique Llugcha, Nancy Llugcha, Segundo Muyulema, Cesar Ocampo, Elsa Ocampo, Víctor Manuel Ocampo, Natalia Robayo ... Huy, Chien, Eri Sofiari, Fengyi Wang, Jong Chol, Kwon Min, Young-Il Hahm and Karma Nidup); Willy Pradel and ...
ABSTRACT A means for determining the rate of release, Q (spores per square meter per second), of ... more ABSTRACT A means for determining the rate of release, Q (spores per square meter per second), of spores from a source of inoculum is paramount for quantifying their further dispersal and the potential spread of disease. Values of Q were obtained for Phytophthora infestans sporangia released from an area source of diseased plants in a potato canopy by comparing the concentrations of airborne sporangia measured at several heights above the source, with the concentrations predicted by a Lagrangian Stochastic simulation model. An independent estimate of Q was obtained by quantifying the number of sporangia per unit area of source at the beginning of each sampling day by harvesting diseased plant tissue and enumerating sporangia from these samples. This standing spore crop was the potential number of sporangia released per area of source during the day. The standing spore crop was apportioned into time segments corresponding to sporangia concentration measurement periods using the time t...
The aggressiveness of four Phytophthora infestans isolates collected from wild and cultivated pot... more The aggressiveness of four Phytophthora infestans isolates collected from wild and cultivated potato species (sect. Petota ) and the level of resistance of nine Petota species were assessed in the highland tropics of Ecuador. For this, isolates of P. infestans were inoculated on whole plants of Petota species in the field and net house and six epidemiological components -infection frequency (IF), incubation period (IP), latent period (LP), lesion size (LS), lesion growth rate (LGR), and relative area under the lesion expansion curve (RAULEC) -were measured during a single infection cycle. Additionally, host specificity was determined by testing for a significant host by pathogen interaction using the same components. The results showed significant differences among isolates of the EC-1 clonal lineage for IP, IF, and RAULEC. Significant differences among isolates were not found for the other components measured. There were significant differences in resistance among the accessions of Petota hosts tested. RAULEC, LGR, LP, and LS were in general more adequate in differentiating among the more resistant and more susceptible accessions but the importance of each component varied with host species. There was slight and inconsistent evidence for the existence of host specificity in some isolates of Petota hosts. IP was the only component for which a significant host by isolate interaction was observed and in most cases the isolates had the greatest aggressiveness on their hosts of origin.
Kromann, P., Taipe, A., Andrade-Piedra, J. L., Munk, L., and Forbes, G. A. 2008. Preemergence inf... more Kromann, P., Taipe, A., Andrade-Piedra, J. L., Munk, L., and Forbes, G. A. 2008. Preemergence infection of potato sprouts by Phytophthora infestans in the highland tropics of Ecuador. Plant Dis. 92:569-574.
ABSTRACT A means for determining the rate of release, Q (spores per square meter per second), of ... more ABSTRACT A means for determining the rate of release, Q (spores per square meter per second), of spores from a source of inoculum is paramount for quantifying their further dispersal and the potential spread of disease. Values of Q were obtained for Phytophthora infestans sporangia released from an area source of diseased plants in a potato canopy by comparing the concentrations of airborne sporangia measured at several heights above the source, with the concentrations predicted by a Lagrangian Stochastic simulation model. An independent estimate of Q was obtained by quantifying the number of sporangia per unit area of source at the beginning of each sampling day by harvesting diseased plant tissue and enumerating sporangia from these samples. This standing spore crop was the potential number of sporangia released per area of source during the day. The standing spore crop was apportioned into time segments corresponding to sporangia concentration measurement periods using the time trace of sporangia sampled above the source by a Burkard continuous suction spore sampler. This apportionment of the standing spore crop yielded potential release rates that were compared with modeled release rates. The two independent estimates of Q were highly correlated (P = 0.003), indicating that the model has utility for predicting release rates for P. infestans sporangia and the spread of disease between fields.
Andrade-Piedra, J. L., Forbes, G. A., Shtienberg, D., Grünwald, N. J., Chacón, M. G., Taipe, M. V... more Andrade-Piedra, J. L., Forbes, G. A., Shtienberg, D., Grünwald, N. J., Chacón, M. G., Taipe, M. V., Hijmans, R. J., and Fry, W. E. 2005. Qualification of a plant disease simulation model: Performance of the LATEBLIGHT model across a broad range of environments. Phytopathology 95:1412-1422.
Andrade-Piedra, J. L., Hijmans, R. J., Juárez, H. S., Forbes, G. A., Shtienberg, D., and Fry, W. ... more Andrade-Piedra, J. L., Hijmans, R. J., Juárez, H. S., Forbes, G. A., Shtienberg, D., and Fry, W. E. 2005. Simulation of potato late blight in the Andes. II: Validation of the LATEBLIGHT model. Phytopathology 95:1200-1208.
Andrade-Piedra, J. L., Hijmans, R. J., Forbes, G. A., Fry, W. E., and Nelson, R. J. 2005. Simulat... more Andrade-Piedra, J. L., Hijmans, R. J., Forbes, G. A., Fry, W. E., and Nelson, R. J. 2005. Simulation of potato late blight in the Andes. I: Modification and parameterization of the LATEBLIGHT model. Phytopathology 95:1191-1199.
Knowledge Management for Development Journal, 2011
Papa Andina began as a regional research program focusing on the Andean potato sectors of Bolivia... more Papa Andina began as a regional research program focusing on the Andean potato sectors of Bolivia, Ecuador and Peru, but later shifted its focus to facilitating pro-poor innovation. To accomplish this shift, a number of approaches were developed to foster innovation, by facilitating mutual learning and collective action among individuals and groups with differing, often conflicting, interests. This paper explains why and how Papa Andina shifted its focus from conducting research to facilitating innovation, and describes two approaches that Papa Andina developed to facilitate mutual learning and innovation: the 'participatory market chain approach' and 'horizontal evaluation'. Differing local circumstances and beliefs shaped the work of local teams, and rivalry among the teams stimulated creativity and innovation. Participatory evaluations helped individuals recognize and appreciate differences and build shared knowledge across the teams. After describing the case, the paper discusses the implications for knowledge management and innovation theory, and for the potential use of Papa Andina's approaches in other settings.
This paper analyzes the impact of participation in multi-stakeholder platforms (Plataformas) aime... more This paper analyzes the impact of participation in multi-stakeholder platforms (Plataformas) aimed at linking smallholder potato farmers to the market in the mountain region of Ecuador. It describes and evaluates the Plataformas' program to determine whether it has been successful in linking farmers to higher-value markets and the effects that such connections have brought, particularly with regard to farmers' welfare and to the environment. The analysis is run comparing a set of different and carefully constructed control groups to beneficiaries and using various specifications. Results are strongly consistent across the different specifications and are sound across the counterfactuals, suggesting impacts are adequately identified. Findings suggest that the program was successful in improving the welfare of beneficiaries, while potential negative environmental impacts, particularly with relation to agrobiodiversity and use of agrochemicals seem not to be a concern. Mechanisms through which impacts have been achieved are analyzed. Little spillover effects are found.
International Journal of Agricultural Sustainability, 2011
Value chains linked to urban markets and agro-industry present new opportunities for adding value... more Value chains linked to urban markets and agro-industry present new opportunities for adding value and raising rural incomes. Small farmers, who produce small volumes, struggle to enter these markets. A lack of trust among value chain actors increases transaction costs and shortcircuits innovation. This paper explores how multi-stakeholder platforms have been used to address these problems in potato based value chains in Bolivia, Peru and Ecuador. It uses the Institutional Analysis and Development (IAD) framework to understand how platforms work. Differences in characteristics of the value chains, the participating actors and institutional arrangements have led to the emergence of two types of platform. The first type brings traders, processors, supermarkets, and others together with farmer associations and research and development (R&D) organizations to foster the development of new market opportunities through commercial, institutional and technological innovation. The second type is structured around geographically delimited supply areas, meshing farmers and service providers to address market governance issues in assuring volumes, meeting quality and timeliness constraints and empowering farmers. Evidence from these cases indicates that platforms that bring stakeholders together around value chains can result in new products, processes, norms, and behaviors that benefit poor farmers, which could not have been achieved otherwise.
Strategies based on using the translaminar fungicide cymoxanil for control of potato late blight,... more Strategies based on using the translaminar fungicide cymoxanil for control of potato late blight, caused by Phytophthora infestans, were compared in the highland tropics of Ecuador in three separate field experiments. In one strategy, a commercial formulation of cymoxanil mixed with mancozeb was sprayed sequentially three times early in the season; this was then followed by three sequential sprays of a commercial product containing mancozeb alone. For the other strategy, the same commercial products were alternated. For each strategy, a spray interval of 14 d was used after the contact/translaminar mixture and 10 d after sprays containing mancozeb alone. Both strategies were evaluated with a manually operated knapsack sprayer but with two levels of application quality. High quality was achieved with a constant pressure valve and a new nozzle, while for low quality, fungicide was applied without a valve and using a damaged nozzle. All treatment combinations gave adequate disease control and no consistent effect of application strategy or application quality could be measured on disease severity or yield. However, approximately twice the volume of fungicide was applied using poor quality equipment, regardless of the application strategy. Advantages and disadvantages of the strategies and their potential effects on fungicide resistance are discussed. r
Potato is the fastest growing major crop in the developing world with important economic impact o... more Potato is the fastest growing major crop in the developing world with important economic impact on many resource-poor farming families. Many factors limit production and profitability, with hundreds of millions of dollars spent yearly on fungicides alone, but little is known about direct losses, with experts agreeing that they are variable and frequently significant. Late blight is most severe in the mountainous areas of developing countries where weather conditions are favorable for disease. Variable topography and continuous production of potato and other late blight hosts, including tomato and in the Andes pear melon, make prediction of disease initiation or severity difficult.
Blandón-Díaz, J. U., Forbes, G. A., Andrade-Piedra, J. L., and Yuen, J. E. 2011. Assessing the ad... more Blandón-Díaz, J. U., Forbes, G. A., Andrade-Piedra, J. L., and Yuen, J. E. 2011. Assessing the adequacy of the simulation model LATEBLIGHT under Nicaraguan conditions. Plant Dis. 95:839-846.
... Guerrero, Armando Espín, Luis Espín, Enrique Llugcha, Nancy Llugcha, Segundo Muyulema, Cesar ... more ... Guerrero, Armando Espín, Luis Espín, Enrique Llugcha, Nancy Llugcha, Segundo Muyulema, Cesar Ocampo, Elsa Ocampo, Víctor Manuel Ocampo, Natalia Robayo ... Huy, Chien, Eri Sofiari, Fengyi Wang, Jong Chol, Kwon Min, Young-Il Hahm and Karma Nidup); Willy Pradel and ...
ABSTRACT A means for determining the rate of release, Q (spores per square meter per second), of ... more ABSTRACT A means for determining the rate of release, Q (spores per square meter per second), of spores from a source of inoculum is paramount for quantifying their further dispersal and the potential spread of disease. Values of Q were obtained for Phytophthora infestans sporangia released from an area source of diseased plants in a potato canopy by comparing the concentrations of airborne sporangia measured at several heights above the source, with the concentrations predicted by a Lagrangian Stochastic simulation model. An independent estimate of Q was obtained by quantifying the number of sporangia per unit area of source at the beginning of each sampling day by harvesting diseased plant tissue and enumerating sporangia from these samples. This standing spore crop was the potential number of sporangia released per area of source during the day. The standing spore crop was apportioned into time segments corresponding to sporangia concentration measurement periods using the time t...
The aggressiveness of four Phytophthora infestans isolates collected from wild and cultivated pot... more The aggressiveness of four Phytophthora infestans isolates collected from wild and cultivated potato species (sect. Petota ) and the level of resistance of nine Petota species were assessed in the highland tropics of Ecuador. For this, isolates of P. infestans were inoculated on whole plants of Petota species in the field and net house and six epidemiological components -infection frequency (IF), incubation period (IP), latent period (LP), lesion size (LS), lesion growth rate (LGR), and relative area under the lesion expansion curve (RAULEC) -were measured during a single infection cycle. Additionally, host specificity was determined by testing for a significant host by pathogen interaction using the same components. The results showed significant differences among isolates of the EC-1 clonal lineage for IP, IF, and RAULEC. Significant differences among isolates were not found for the other components measured. There were significant differences in resistance among the accessions of Petota hosts tested. RAULEC, LGR, LP, and LS were in general more adequate in differentiating among the more resistant and more susceptible accessions but the importance of each component varied with host species. There was slight and inconsistent evidence for the existence of host specificity in some isolates of Petota hosts. IP was the only component for which a significant host by isolate interaction was observed and in most cases the isolates had the greatest aggressiveness on their hosts of origin.
Kromann, P., Taipe, A., Andrade-Piedra, J. L., Munk, L., and Forbes, G. A. 2008. Preemergence inf... more Kromann, P., Taipe, A., Andrade-Piedra, J. L., Munk, L., and Forbes, G. A. 2008. Preemergence infection of potato sprouts by Phytophthora infestans in the highland tropics of Ecuador. Plant Dis. 92:569-574.
ABSTRACT A means for determining the rate of release, Q (spores per square meter per second), of ... more ABSTRACT A means for determining the rate of release, Q (spores per square meter per second), of spores from a source of inoculum is paramount for quantifying their further dispersal and the potential spread of disease. Values of Q were obtained for Phytophthora infestans sporangia released from an area source of diseased plants in a potato canopy by comparing the concentrations of airborne sporangia measured at several heights above the source, with the concentrations predicted by a Lagrangian Stochastic simulation model. An independent estimate of Q was obtained by quantifying the number of sporangia per unit area of source at the beginning of each sampling day by harvesting diseased plant tissue and enumerating sporangia from these samples. This standing spore crop was the potential number of sporangia released per area of source during the day. The standing spore crop was apportioned into time segments corresponding to sporangia concentration measurement periods using the time trace of sporangia sampled above the source by a Burkard continuous suction spore sampler. This apportionment of the standing spore crop yielded potential release rates that were compared with modeled release rates. The two independent estimates of Q were highly correlated (P = 0.003), indicating that the model has utility for predicting release rates for P. infestans sporangia and the spread of disease between fields.
Andrade-Piedra, J. L., Forbes, G. A., Shtienberg, D., Grünwald, N. J., Chacón, M. G., Taipe, M. V... more Andrade-Piedra, J. L., Forbes, G. A., Shtienberg, D., Grünwald, N. J., Chacón, M. G., Taipe, M. V., Hijmans, R. J., and Fry, W. E. 2005. Qualification of a plant disease simulation model: Performance of the LATEBLIGHT model across a broad range of environments. Phytopathology 95:1412-1422.
Andrade-Piedra, J. L., Hijmans, R. J., Juárez, H. S., Forbes, G. A., Shtienberg, D., and Fry, W. ... more Andrade-Piedra, J. L., Hijmans, R. J., Juárez, H. S., Forbes, G. A., Shtienberg, D., and Fry, W. E. 2005. Simulation of potato late blight in the Andes. II: Validation of the LATEBLIGHT model. Phytopathology 95:1200-1208.
Andrade-Piedra, J. L., Hijmans, R. J., Forbes, G. A., Fry, W. E., and Nelson, R. J. 2005. Simulat... more Andrade-Piedra, J. L., Hijmans, R. J., Forbes, G. A., Fry, W. E., and Nelson, R. J. 2005. Simulation of potato late blight in the Andes. I: Modification and parameterization of the LATEBLIGHT model. Phytopathology 95:1191-1199.
Knowledge Management for Development Journal, 2011
Papa Andina began as a regional research program focusing on the Andean potato sectors of Bolivia... more Papa Andina began as a regional research program focusing on the Andean potato sectors of Bolivia, Ecuador and Peru, but later shifted its focus to facilitating pro-poor innovation. To accomplish this shift, a number of approaches were developed to foster innovation, by facilitating mutual learning and collective action among individuals and groups with differing, often conflicting, interests. This paper explains why and how Papa Andina shifted its focus from conducting research to facilitating innovation, and describes two approaches that Papa Andina developed to facilitate mutual learning and innovation: the 'participatory market chain approach' and 'horizontal evaluation'. Differing local circumstances and beliefs shaped the work of local teams, and rivalry among the teams stimulated creativity and innovation. Participatory evaluations helped individuals recognize and appreciate differences and build shared knowledge across the teams. After describing the case, the paper discusses the implications for knowledge management and innovation theory, and for the potential use of Papa Andina's approaches in other settings.
This paper analyzes the impact of participation in multi-stakeholder platforms (Plataformas) aime... more This paper analyzes the impact of participation in multi-stakeholder platforms (Plataformas) aimed at linking smallholder potato farmers to the market in the mountain region of Ecuador. It describes and evaluates the Plataformas' program to determine whether it has been successful in linking farmers to higher-value markets and the effects that such connections have brought, particularly with regard to farmers' welfare and to the environment. The analysis is run comparing a set of different and carefully constructed control groups to beneficiaries and using various specifications. Results are strongly consistent across the different specifications and are sound across the counterfactuals, suggesting impacts are adequately identified. Findings suggest that the program was successful in improving the welfare of beneficiaries, while potential negative environmental impacts, particularly with relation to agrobiodiversity and use of agrochemicals seem not to be a concern. Mechanisms through which impacts have been achieved are analyzed. Little spillover effects are found.
International Journal of Agricultural Sustainability, 2011
Value chains linked to urban markets and agro-industry present new opportunities for adding value... more Value chains linked to urban markets and agro-industry present new opportunities for adding value and raising rural incomes. Small farmers, who produce small volumes, struggle to enter these markets. A lack of trust among value chain actors increases transaction costs and shortcircuits innovation. This paper explores how multi-stakeholder platforms have been used to address these problems in potato based value chains in Bolivia, Peru and Ecuador. It uses the Institutional Analysis and Development (IAD) framework to understand how platforms work. Differences in characteristics of the value chains, the participating actors and institutional arrangements have led to the emergence of two types of platform. The first type brings traders, processors, supermarkets, and others together with farmer associations and research and development (R&D) organizations to foster the development of new market opportunities through commercial, institutional and technological innovation. The second type is structured around geographically delimited supply areas, meshing farmers and service providers to address market governance issues in assuring volumes, meeting quality and timeliness constraints and empowering farmers. Evidence from these cases indicates that platforms that bring stakeholders together around value chains can result in new products, processes, norms, and behaviors that benefit poor farmers, which could not have been achieved otherwise.
Strategies based on using the translaminar fungicide cymoxanil for control of potato late blight,... more Strategies based on using the translaminar fungicide cymoxanil for control of potato late blight, caused by Phytophthora infestans, were compared in the highland tropics of Ecuador in three separate field experiments. In one strategy, a commercial formulation of cymoxanil mixed with mancozeb was sprayed sequentially three times early in the season; this was then followed by three sequential sprays of a commercial product containing mancozeb alone. For the other strategy, the same commercial products were alternated. For each strategy, a spray interval of 14 d was used after the contact/translaminar mixture and 10 d after sprays containing mancozeb alone. Both strategies were evaluated with a manually operated knapsack sprayer but with two levels of application quality. High quality was achieved with a constant pressure valve and a new nozzle, while for low quality, fungicide was applied without a valve and using a damaged nozzle. All treatment combinations gave adequate disease control and no consistent effect of application strategy or application quality could be measured on disease severity or yield. However, approximately twice the volume of fungicide was applied using poor quality equipment, regardless of the application strategy. Advantages and disadvantages of the strategies and their potential effects on fungicide resistance are discussed. r
Potato is the fastest growing major crop in the developing world with important economic impact o... more Potato is the fastest growing major crop in the developing world with important economic impact on many resource-poor farming families. Many factors limit production and profitability, with hundreds of millions of dollars spent yearly on fungicides alone, but little is known about direct losses, with experts agreeing that they are variable and frequently significant. Late blight is most severe in the mountainous areas of developing countries where weather conditions are favorable for disease. Variable topography and continuous production of potato and other late blight hosts, including tomato and in the Andes pear melon, make prediction of disease initiation or severity difficult.
Blandón-Díaz, J. U., Forbes, G. A., Andrade-Piedra, J. L., and Yuen, J. E. 2011. Assessing the ad... more Blandón-Díaz, J. U., Forbes, G. A., Andrade-Piedra, J. L., and Yuen, J. E. 2011. Assessing the adequacy of the simulation model LATEBLIGHT under Nicaraguan conditions. Plant Dis. 95:839-846.
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Papers by Jorge Andrade-piedra