Abstract

CALDERON-CERDAS, Rubén  and  ARAYA-FERNANDEZ, Carlos Manuel. Symptoms of common bean ''amachamiento''. Tecnología en Marcha [online]. 2022, vol.35, n.3, pp.158-166. ISSN 0379-3982.  http://dx.doi.org/10.18845/tm.v35i3.5716.

The ''amachamiento'' of the common bean is caused by the leaf nematode Aphelenchoides besseyi Christie. The disease can be recognized through the symptoms of angular necrotic tissue, foliar deformation, late senescence and pods absence. Initially, the symptoms of angular necrosis were called false angular spot. In addition, incorrectly the leaf deformation was diagnosed as a viral disease. This work establishes and describes the symptoms of ''amachamiento''. Based on the literature, field observations and experience of the bean growers, the bean tissue was analyzed to describe the symptoms. In 2014 and 2015, twenty-four Costa Rican farms were visited (San José and Puntarenas provinces); plant material was collected from each farm. Leaf deformation is the predominant symptom, present in 83% of plants; whereas the angular necrosis in 45% of the plants with ''amachamiento''. The pods number decline was 46% compared to healthy plants. The late senescence was evident in diseased plants, that plants had higher relative chlorophyll content (54 SPAD). The healthy plants had a low chlorophyll content (37 SPAD). Through the recognition of the symptoms of ''amachamiento'', it is possible to have an accurate diagnosis of the disease.

Keywords : False angular leaf spot; leaf nematode; Aphelenchoides besseyi; Phaseolus vulgaris.

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