Validación de estrategias de PROINPA para el control químico de la rancha (Phytophthora infestans) de la papa en Huánuco Perú
Authors
Villodas Rosales, Luis
Abstract
Con el objetivo de validar y ajustar las estrategias de PROINPA para el control químico de la rancha de la papa en cultivares susceptibles y complementar el control químico con la resistencia, se realizaron tres ensayos en Mayobamba (Huánuco) utilizando cultivares locales. En el Ensayo 1 la estrategia de PROINP A para cultivares susceptibles se aplicó en Amarilla Tumbay y en Canchán y la estrategia para cultivares resistentes en Amarilis, Canchán y en dos clones de papa pre-seleccionados por su resistencia a rancha. En ambas estrategias se utilizaron los fungicidas cimoxanil + propineb y el clorotalonil. La severidad de la enfermedad fue evaluada visualmente con la ayuda de una escala diagramática, con los datos de severidad se calculó el Área Bajo la· Curva de Progreso de la Enfermedad (AUDPC). Asimismo, se evaluó el rendimiento, se cuantificó la esporulación y se realizó una prueba de sensibilidad in vitro de P. infestans al metalaxil. Las estrategias de PROINP A permitieron un control efectivo de la rancha obteniéndose rendimientos superiores con reducciones de 30-50% y de y 44-70% de fungicidas aplicados en cultivares susceptibles y resistentes respectivamente. Los cultivares Canchán y Amarilis mostraron niveles bajos de resistencia que no permitieron ahorros significativos de fungicidas aplicados bajo condiciones favorables para la rancha. Un clan previamente seleccionado por los agricultores a partir de material original obtenido del Centro Internacional de la Papa (CIP), mostró un nivel apropiado de resistencia a la rancha. Todos los aislamientos de Phytophthora infestans ensayados in vitro mostraron ser resistentes al metalaxil a las concentraciones de 5 y 1 00 ppm. En el Ensayo 2, utilizando el cultivar susceptible Amarilla Tumbay se aplicó dos programas calendarizados (cada 5 y 10 días) utilizando los fungicidas: cimoxanil + propineb, mefenoxam + mancozeb y el clorotalonil, mientras que en la estrategia PROINP A se utilizaron los fungicidas en parejas: cimoxanil + propineb con clorotalonil y mefenoxam + mancozeb con clorotalonil. La aplicación de clorotalonil cada 5 días controló mejor la enfermedad, tuvo el mayor rendimiento y el mayor beneficio económico neto. El mefenoxam. y el cimoxanil utilizados dentro de la estrategia de PROINP A tuvieron una performance aceptable, aunque la población de P. infestans mostró reducida sensibilidad a los fungicidas sistémicos utilizados. Se requirió de aplicaciones a intervalos muy cortos de cinco días para una mejor acción de cimoxanil. Se determinó una correlación altamente significativa entre el tiempo y el crecimiento de la lesión causada por P. irifestans. El Ensayo 3, fue similar al Ensayo 2 pero utilizando el cultivar resistente Amarilis. Los resultados demostraron que este cultivar se comportó como susceptible y que para un buen control de la rancha, bajo condiciones del experimento, requirió de al menos 15 aplicaciones de fungicidas cada 5 días. La aplicación cada 5 días, de mefenoxam + mancozeb y cimoxanil + propineb incrementó significativamente el rendimiento y el beneficio económico respectivamente. Sin embargo, utilizando la estrategia PROINPA se redujo en 30% el número de aplicaciones con sólo 7% de reducción en los rendimientos. Estos resultados confirman que el intervalo de 1 O días entre aplicaciones de los tres fungicidas utilizados en el presente trabajo resultó muy largo para un control efectivo de la rancha bajo las condiciones medio ambientales y de población de P. irifestans de Mayobamba.
In order to validate and adapt PROINPA strategies for chemical control of potato late blight in susceptible potato cultivars and complement it with resistance, three trials were conducted in Mayobamba (Huánuco) using local cultivars. PROINPA strategy for susceptible cultivars was applied in AmarillaTumbay and Canchán and strategy for resistant cultivars to Amarilis, Canchán and two clones pre-selected for resistance to potato late blight. In both strategies the cimoxanil/propineb fungicides and clorotalonil were used. The disease severity was assessed visually with the help of a diagrammatic scale, the area under the disease progress curve (AUDPC) and the tuber yield were calculated. Moreover, the sporulation and the sensitivity of Phytophthora infestans to metalaxil were measured by in vitro tests. Effective control of late blight and high tuber yields with fungicides reductions by 30-50% and 44-70% in susceptible and resistant cultivars, respectively were obtained with PROINPA strategies. The Canchán and Amarilis cultivars showed low levels of resistance that did not allow significant savings of fungicides applied under favorable conditions for late blight. A clone previously selected by farmers from original material obtained from the International Potato Center (CIP), showed an appropriate level of resistance to late blight. All isolates of P. infestans were shown to be resistant to metalaxil at concentrations of 5 to 100 ppm. Using the susceptible cultivar AmarillaTumbay with two programs of fungicides application (5- or 10-day intervals): cimoxanil/propineb or mefenoxam/mancozeb or clorotalonil, while in the PROINPA strategy fungicides were used in pairs: cimoxanil/propineb with clototalonil or mefenoxam/mancozeb with clorotalonil. Applying clorotalonil at 5-day intervals the disease was effectively controlled, and tuber yield and net profit showed the highest values. The mefenoxam and cimoxanil used within the PROINPA strategy had acceptable performance, even with a population of P. infestans showing reduced sensibility to metalaxil. The best action of cimoxanil was observed when the applications were at 5-day intervals. A highly significant positive correlation between time and growth of the lesion caused by P. infestans was determined. Using the resistant cultivar Amarilis, our results showed that this cultivar behaved as susceptible and acceptable level of late blight control required at least 15 fungicide applications at 5-day intervals. The 5-day intervals of mefenoxam/mancozeb or cymoxanil/propineb significantly increased the tuber yield and the net profit. However, using the PROINPA strategy the number of applications and tuber yield were reduced by 30% and 7%, respectively. These results confirmed that the 10-day intervals between applications of the three fungicides used in this study was too long for effective control of late blight under the environmental conditions and population of P. infestans at Mayobamba.
In order to validate and adapt PROINPA strategies for chemical control of potato late blight in susceptible potato cultivars and complement it with resistance, three trials were conducted in Mayobamba (Huánuco) using local cultivars. PROINPA strategy for susceptible cultivars was applied in AmarillaTumbay and Canchán and strategy for resistant cultivars to Amarilis, Canchán and two clones pre-selected for resistance to potato late blight. In both strategies the cimoxanil/propineb fungicides and clorotalonil were used. The disease severity was assessed visually with the help of a diagrammatic scale, the area under the disease progress curve (AUDPC) and the tuber yield were calculated. Moreover, the sporulation and the sensitivity of Phytophthora infestans to metalaxil were measured by in vitro tests. Effective control of late blight and high tuber yields with fungicides reductions by 30-50% and 44-70% in susceptible and resistant cultivars, respectively were obtained with PROINPA strategies. The Canchán and Amarilis cultivars showed low levels of resistance that did not allow significant savings of fungicides applied under favorable conditions for late blight. A clone previously selected by farmers from original material obtained from the International Potato Center (CIP), showed an appropriate level of resistance to late blight. All isolates of P. infestans were shown to be resistant to metalaxil at concentrations of 5 to 100 ppm. Using the susceptible cultivar AmarillaTumbay with two programs of fungicides application (5- or 10-day intervals): cimoxanil/propineb or mefenoxam/mancozeb or clorotalonil, while in the PROINPA strategy fungicides were used in pairs: cimoxanil/propineb with clototalonil or mefenoxam/mancozeb with clorotalonil. Applying clorotalonil at 5-day intervals the disease was effectively controlled, and tuber yield and net profit showed the highest values. The mefenoxam and cimoxanil used within the PROINPA strategy had acceptable performance, even with a population of P. infestans showing reduced sensibility to metalaxil. The best action of cimoxanil was observed when the applications were at 5-day intervals. A highly significant positive correlation between time and growth of the lesion caused by P. infestans was determined. Using the resistant cultivar Amarilis, our results showed that this cultivar behaved as susceptible and acceptable level of late blight control required at least 15 fungicide applications at 5-day intervals. The 5-day intervals of mefenoxam/mancozeb or cymoxanil/propineb significantly increased the tuber yield and the net profit. However, using the PROINPA strategy the number of applications and tuber yield were reduced by 30% and 7%, respectively. These results confirmed that the 10-day intervals between applications of the three fungicides used in this study was too long for effective control of late blight under the environmental conditions and population of P. infestans at Mayobamba.
Description
Universidad Nacional Agraria La Molina. Escuela de Posgrado. Maestría en Fitopatología
Keywords
Huanuco (Dpto), Tizón tardío, Rancha, Solanum tuberosum, Phytophthora infestans, Control químico, Métodos de control, Evaluación, Agroquímicos, Agencias de desarrollo, Bolivia, Perú, PROINPA
Citation
Date
2015
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