Abstract

Yield losses caused by bean amachamiento and reaction
of commercial germoplasm to disease. Yield losses
caused by common bean “amachamiento” (Aphelenchoides
besseyi) was determined in fi eld 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 fi elds 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 quantifi ed in each micro-plot
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, Chánguena, Cabécar, Gibre, Chirripó, Guaymí
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
fi eld 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-signifi cant. None of the bean commercial varieties
showed resistance to the disease.
Keywords: Aphelenchoides besseyi, Phaseolus vulgaris L., foliar nematode, false angular leaf spot.