The relationships between cassava (Manihot esculenta Crantz), ecosystems, diseases and pests and their influence on breeding strategy

Con base en consideraciones relacionadas con las caracteristicas de la yuca, sus centros de origen y el sistema tradicional de cultivo, se derivaron varias conclusiones con respecto a las relaciones de la planta con los factores negativos de la produccion (FNP), los cuales comprenden presiones debidas a enfermedades, plagas, factores climaticos y edaficos. Se concluye que: 1) la existencia y/o severidad de las enfermedades y plagas se relacionan con las caracteristicas del ecosistema; 2) no hay evidencia de especializacion por razas entre los patogenos y plagas de la yuca; 3) la resistencia a los FNP es estable; 4) los clones de yuca son var. adaptadas regionalmente; 5) Manihot esculenta posee probablemente resistencia a los FNP existentes en los diferentes ecosistemas debido a que su seleccion se ha hecho en un amplio rango de ecosistema; 6) es posible encontrar clones de M. esculenta con resistencia a todos los FNP de un ecosistema dado; 7) con base en las consideraciones anteriores, se sugiere que se deberian descentralizar los programas de fitomejoramiento; para incluir varios ecosistemas representativos como sitios de seleccion. (CIAT)

Based on the considerations related to the characteristics of cassava, centers of origin, and the traditional system of cultivation, several conclusions were made regarding the relationships between the plant and NPFs, constituted by disease and pest pressures and edaphic and climatic factors. It is concluded that: (1) the existence and/or severity of diseases and pest are related to the characteristics of the ecosystem; (2) there appears to be no evidence of race specialization among pathogens and pests of cassava; (3) resistance to NPFs appears to be stable; (4) cassava clones are regionally adapted var.; (5) Manihot esculenta probably has resistance to most NPFs existing in the different ecosystems since it has been selected under a wide range of ecosystems; (6) it is possible to find clones of M. esculenta with resistance to all the NPFs in a given ecosystem; and (7) on the basis of the aforementioned considerations, it is suggested that plant breeding programs should be decentralized to include several representative ecosystems as selection sites. (CIAT)