Pérdidas causadas por el amachamiento del frijol (Aphelenchoides besseyi Christie) y reacción del germoplasma comercial al patógeno

yield losses caused by common bean “amachamiento” (aphelenchoides besseyi) was determined in field plots from 2007 through 2008 in the brunca and huetar norte production regions of costa rica, as well as the reaction of commercial varieties to the pathogen during 2009 in the brunca region. in common bean seed reproduction fields of the cultivar cabecar, 83 micro-plots (3 m long on rows) were established to evaluate yield losses, during the v3 or v4, r6 and r8 phenological stages. yield components were quantified in each microplot and by regression and correlation statistical analysis yield losses were estimated. the bean cultivar reaction to the disease was evaluated by natural inoculum pressure in ten plants of bribri, changuena, cabecar, gibre, chirripo, guaymi and brunca varieties; pod production was compared to non-inoculated plants. t-tests for independent samples was applied to this plant population. yield losses in the field reached 71 to 80% in pod production and 70 to 85% in yield. seeds per pod (0-16%) and 100-seed weight (0-19%) were non-significant. none of the bean commercial varieties showed resistance to the disease.