Short communication. Telluric pathogens isolated from bean plants with collar and root rots in northwest Spain

摘要

Pathogens belonging to the disease complex responsible for bean collar and root rots in northwest Spain were identified and their pathogenic behaviour studied over a two year period (2004-2005). The potential fungal and oomycete pathogens Fusarium solani f. sp. phaseoli (Burkh.) W.C. Snyder & Hansen, Rhizoctonia solani Kühn, Pythium ultimum Trow, Pythium Group G, Fusarium avenaceum (Fr.) Sacc., F. culmorum W. G. Sm. (Sacc.), Botrytis cinérea Pers., Sclerotinia sclerotiorum (Lib.) de Bary and Sclerotium rolfsii Sacc. were isolated from 419 bean (Phaseolus vulgaris L.) plants affected by collar or root rot. Fusarium solani f. sp. phaseoli was the most frequently isolated (found on 63.7% of the farms surveyed and isolated from 19.3% of the diseased plants), followed by R. solani and the Pythium species. Inoculating Phaseolus vulgaris cv. Música and Zondra with 14 isolates of these fungi and oomycetes showed F. solani f. sp. phaseoli to be the most aggressive pathogen of the complex; F. avenaceum and F. culmorum were found not to be pathogenic for either cultivar. The results confirm that F. solani and R. solani are the main pathogens of the bean collar/root rot disease complex in northwest Spain, affecting crops in their early growth stages. The complex also includes P. ultimum and Pythium Group G.