Resumo

NAVARRETE-MAYA, Rosa et al. Reaction of common bean genotypes to Fusarium spp. y Rhizoctonia solani under field and greenhose conditions. Agric. Téc. Méx [online]. 2009, vol.35, n.4, pp.459-470. ISSN 0568-2517.

The root rot induced damage caused by R. solani and Fusarium spp. affects common bean (Phaseolus vulgaris L.) production at the highlands of Mexico. To identify bean genotypes resistant to both fungi, two experiments were conductedunderfieldand greenhouse conditions. In the field, under rainfed conditions, 15 bean genotypes were planted on July 24 2001, at Texcoco, state of Mexico. Incidence and attack severity were determined at the phenological stages V₃, R₅, R₇ and R8; also, daily temperature and precipitation were recorded. The same genotypes were planted under greenhouse conditions on July 27th, 2001 in pots with soil from the same site. Plant samples were collected from all genotypes for isolation and identification of fungi causing root rots. Both,R. solani and Fusarium spp. were recovered. Under field conditions, root rots were observed throughout the cycle, with the greatest severity at the R₅ and R₇ stages, no immune genotypes were observed. Cultivar Negro Tacana showed intermediate resistance to Fusarium spp. and G 12729 (a wild genotype) was resistant during the early phenological stages. Under greenhouse conditions, any genotype showed a consistent resistance pattern during the cycle. Atthe field, the attack by R. solani was less severe than that of Fusarium spp., whereas in the greenhouse the attack R. solani was severe. Atthe field, cultivars Pinto Villa, Wisc RRR, PI 203,958 and BAT 477 were intermediate and consistent in its response to both fungi; however, were susceptible in the greenhouse. The disease incidence and severity on the genotypes showed differences related to climatic conditions registered during the growth cycle.

Palavras-chave : Phaseolus vulgaris; climate; incidence; root-rots.