Guia ambiental para el cultivo de la papa.

Papa-Solanum tuberosu

Fungicida protectante vs resistencia poligénica en gota

Papa-Solanum tuberosu

Pastusa suprema

Papa-Solanum tuberosu

Comportamiento y manejo de enfermedades en papa :

Universidad Nacional - UNALpap

Searching for an alternative to manage powdery scab, caused by Spongospora subterranea, in potato

1 recurso en línea (páginas 378-386) : ilustraciones color.One of the main problems in potato production is powdery scab, caused by the protozoan Spongospora subterranea. Currently, there are no effective control strategies for this pathogen, which causes root damage and, therefore, reduces tuber quality. In order to develop a biocontrol alternative for powdery scab, we assessed the effect of eight potential microbial agents belonging to the genera Trichoderma spp., Pseudomonas sp., Bacillus sp. and Streptomyces spp. in the reduction of the disease. Additionally, we evaluated biocarbon, chitin and chitosan, which are organic additives with a biocontrol potential in other pathosystems. Initially, a trial was established to obtain the development of galls in two different locations (Mosquera and Subachoque, Cundinamarca) with two concentrations of protozoan inoculum. Eight weeks after sowing, the disease severity was determined counting the number of galls per plant. Because of the consistent development of the disease, the assays were established in the municipality of Subachoque in potted plants with naturally infested soil (1×103 sporosori/g of soil). All microbial biocontrol agents showed a reduction in gall development (P>0.05). Streptomyces misionensis Ac006 caused the largest reduction in severity (51.41%). Among the organic additives, 0.5% chitosan had the greatest (62.58%) effect on disease reduction, a significant (P≤0.05) effect. Our results suggest possible alternatives for the sustainable management of powdery scab in potato.Entre las principales problemáticas que se presentan en la producción de papa se encuentra Spongospora subterranea (Wallr.) Lagerheim f. sp. subterránea, agente causal de la sarna polvosa y camanduleo, enfermedades que afectan los tubérculos, las raíces, que no cuentan con prácticas de manejo efectivas. Con el fin de generar una alternativa de manejo se evaluó el efecto en la reducción del camanduleo de microorganismos potencialmente biocontroladores de los géneros Trichoderma spp., Pseudomonas sp., Bacillus sp. y Streptomyces spp. Así mismo, se evaluó el biocarbón, la quitina y el quitosán, aditivos orgánicos que han demostrado actividad de control en otros patosistemas. Inicialmente, se estableció un ensayo para obtener el desarrollo de agallas en dos ambientes diferentes (Mosquera y Subachoque, Cundinamarca) y dos concentraciones de inóculo del protozoo. La evaluación se realizó 8 semanas después de la siembra (SDS), midiendo la severidad expresada como número de agallas por planta. Dado el consistente desarrollo de la enfermedad, se decidió establecer los ensayos en el Municipio de Subachoque, usando suelo naturalmente infestado con 1×103 esporosoros/g de suelo. Al aplicar los biocontroladores, se observó disminución (P>0,05) en el desarrollo de agallas con la mayoría de los microorganismos, siendo Streptomyces misionensis Ac006 el que más redujo la enfermedad en un 51,41%. Por otra parte, entre los aditivos evaluados, fue el quitosán al 0,5% con el que se obtuvo una mayor reducción (P≤0,05) en el número de agallas 62,58%. Estos resultados permiten sugerir el uso de estos tratamientos para el manejo del camanduleo de la papa.Bibliografía: páginas 384-386

Rhizoctonia solani AG-3PT is the major pathogen associated with potato stem canker and black scurf in Colombia

Stem canker and black scurf diseases of potatoes are caused by the basidiomycetous fungus Tanatephorus cucumeris (ana-morphic species complex Rhizoctonia solani). Tese diseases have worldwide distribution wherever potato is grown but their etiology varies depending on the predominance of distinct R. solani anastomosis groups (AGs) in a particular area. Within the species complex, several AGs have been associated with stem canker or black scurf diseases, including AG-1, AG-2-1, AG-2-2, AG-3, AG-4, AG-5 and AG-9. Tis article reports on the most comprehensive population-based study, providing evidence on the distribution of R. solani AGs in Colombian potato fields. A total of 433 isolates were sampled from the main potato cropping areas in Colombia from 2005 to 2009. Isolates were assigned to AGs by conventional PCR assays using specific primers for AG-3, sequencing of the ITS-rDNA and hyphal interactions. Most of the isolates evaluated were assigned to AG-3PT (88.45%), and a few to AG-2-1 (2.54%). Te remaining isolates were binucleate Rhizoctonia (AG-A, E, and I). Pathogenicity tests on the stems and roots of different plant species, including the potato, showed that AG-3PT affects the stems of solanaceous plants. In other plant species, damage was severe in the roots, but not the stems. AG-2-1 caused stem canker of Solanum tuberosum cv. Capiro and in R. raphanistrum and B. campestris subsp. Rapa plantlets and root rot in other plants. Te results of our study indicated that R. solani AG-3PT was the principal pathogen associated with potato stem canker and black scurf diseases of potatoes in Colombia

Rhizoctonia solani GA-3PT es el principal patógeno asociado con el chancro del tallo y la sarna negra de la papa en Colombia

Stem canker and black scurf diseases of potatoes are caused by the basidiomycetous fungus Tanatephorus cucumeris (ana-morphic species complex Rhizoctonia solani). Tese diseases have worldwide distribution wherever potato is grown but their etiology varies depending on the predominance of distinct R. solani anastomosis groups (AGs) in a particular area. Within the species complex, several AGs have been associated with stem canker or black scurf diseases, including AG-1, AG-2-1, AG-2-2, AG-3, AG-4, AG-5 and AG-9. Tis article reports on the most comprehensive population-based study, providing evidence on the distribution of R. solani AGs in Colombian potato fields. A total of 433 isolates were sampled from the main potato cropping areas in Colombia from 2005 to 2009. Isolates were assigned to AGs by conventional PCR assays using specific primers for AG-3, sequencing of the ITS-rDNA and hyphal interactions. Most of the isolates evaluated were assigned to AG-3PT (88.45%), and a few to AG-2-1 (2.54%). Te remaining isolates were binucleate Rhizoctonia (AG-A, E, and I). Pathogenicity tests on the stems and roots of different plant species, including the potato, showed that AG-3PT affects the stems of solanaceous plants. In other plant species, damage was severe in the roots, but not the stems. AG-2-1 caused stem canker of Solanum tuberosum cv. Capiro and in R. raphanistrum and B. campestris subsp. Rapa plantlets and root rot in other plants. Te results of our study indicated that R. solani AG-3PT was the principal pathogen associated with potato stem canker and black scurf diseases of potatoes in Colombia

The population genetic structure of Rhizoctonia solani AG-3PT from potato in the Colombian Andes

The soilborne fungus Rhizoctonia solani anastomosis group 3 (AG-3PT) is a globally important potato pathogen. However, little is known about the population genetic processes affecting field populations of R. solani AG-3PT, especially in the South American Colombian Andes, which is near the center of diversity of the two most common groups of cultivated potato, Solanum tuberosum and S. phureja. We analyzed the genetic structure of 15 populations of R. solani AG-3PT infecting potato in Colombia using 11 simple-sequence repeat (SSR) markers. In total, 288 different multilocus genotypes were identified among 349 fungal isolates. Clonal fractions within field populations were 7 to 33%. R ST statistics indicated a very low level of population differentiation overall, consistent with high contemporary gene flow, though moderate differentiation was found for the most distant southern populations. Genotype flow was also detected, with the most common genotype found widely distributed among field populations. All populations showed evidence of a mixed reproductive mode, including both asexual and sexual reproduction, but two populations displayed evidence of inbreeding. © 2013 The American Phytopathological Society

Cuantificación de la expresión del gen amo-A en poblaciones bacterianas y archaeales presentes en muestras de suelos de un lote arrocero caracterizado por ambientes

El ciclo del nitrógeno representa uno de los procesos biogeoquímicos más importantes para los ecosistemas terrestres y acuáticos. Las comunidades microbianas desempeñan un papel crucial en los procesos de transformación del nitrógeno en el suelo, ya que participan en diversas etapas como la nitrificación, de gran importancia para la producción agrícola. Dentro de los marcadores moleculares más utilizados para evaluar la actividad de poblaciones microbianas oxidantes de amonio se han considerado ampliamente los genes que codifican enzimas claves como la subunidad A de la actividad amonio monooxigenasa (AMO). Sin embargo, no se comprende completamente si la expresión de esta enzima tiene relación directa con el rendimiento de los cultivos. En este contexto, se evaluó la expresión del gen amo-A de comunidades bacterianas y archaeales presentes en un lote arrocero previamente caracterizado por ambientes. Para cuantificar la abundancia de arqueas y bacterias oxidantes de amonio, (AOA y AOB, respectivamente) se emplearon las técnicas de PCR en tiempo real (RT-qPCR) y PCR digital (RT-dPCR). En este trabajo se encontró a través del análisis de datos metagenómicos que hubo una mayor presencia de AOB en las muestras de suelo rizosférico mientras que las AOA fueron predominantes en las muestras de suelo de soporte “bulk”, sin embargo, no se detectó la expresión del gen amo-A asociada a la comunidad de bacterias en las muestras de suelo analizadas. Por otra parte, no se presentaron diferencias entre los transcritos del gen amo-A asociados a la comunidad de AOA de los ambientes caracterizados. Además, la expresión de transcritos no estuvo relacionada con alguna de las propiedades químicas evaluadas. Finalmente, las estrategias de cuantificación para RT-qPCR (plásmido y templete) resultaron ser homólogas y funcionales para identificar la expresión del gen amo-A de AOA, mientras que la técnica de RT-dPCR fue más precisa para el análisis de la comunidad de AOB y AOA