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 Digital Divide in the University: The Appropriation of ICT in Higher Education Students from Bogota, Colombia

The growth and integration of ICTs in the global economy have created conditions that profoundly affect our society, dividing communities between those who effectively appropriate these resources and those who do not, what is called the digital divide. This exploratory study seeks to propose and validate ways of assessing this phenomenon in higher education, from the construction of a model and a comprehensive methodology that value contextual conditions, in addition to measuring access factors and motivation for use, that have been employed in previous research. To obtain indications about the behavior of this phenomenon, we developed research with students from three universities in Bogota, administering 566 surveys in four phases that would test the variables proposed in the model. The results show that the variables of the model link causally, with the strongest relations between education, attitude towards ICTs and ICT application. Although students have good access to ICTs and high levels of education, no strong relationship was found in regards to perceived impact on production. This may be explained by a superficial appropriation of ICT, due to a context that is alien to its conditions of origin (industrialism, innovation), poor quality of education and economies not centered around R&D.