Effects of cropping systems and previous crop on root rot pathogens of the common bean (Phaseolus vulgaris L.) / Influência de sistemas de cultivo e de sucessões de culturas em patógenos de solo do feijoeiro-comum (Phaseolus vulgaris L.)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Common bean (Phaseolus vulgaris) root rots caused by Fusarium solani f. sp. phaseoli and Rhizoctonia solani, and fusarium wilt (Fusarium oxysporum f. sp. phaseoli), are increasingly limiting factors to the irrigated winter crop in Brazil. The objective of this work was to evaluate the effect of previous crops in the conventional (CC) or no-till cropping systems (NT) on the: soil populations of R. solani and Fusarium spp.; bean seedling damping-off incidence; root rot severities; and the incidence of fusarium wilt. Previous crops included the following legumes: Cajanus cajan, Stylosanthes guianensis (cv. Mineirão), Crotalaria spectabilis, and the following grasses: Pennisetum glaucum (cv. BN-2, millet), Sorghum bicolor (cv. BR 304), Panicum maximum (cv. Mombaça), Brachiaria brizantha (cv. Marandú) and a consortium of corn (Zea mays) and B. brizantha. These crops were planted on the summer (wet) seasons of 2002, 2003 e 2004, and the bean (cv. BRS Valente) crop was planted the correspondent subsequent winters of 2003, 2004 and 2005, irrigated by central pivot. Experiments were done in a strip-plot, following a complete randomized design with four replicates. In general, soil populations of Fusarium spp. and R. solani were higher in the NT cropping system. Legume crop residue increased, and grass crop residue decreased, soil populations of R. solani. A positive correlation was found between bean damping-off incidence and the dry masses of grass crops in the NT cropping system; and positive correlations between damping-off incidence and the percent of organic matter residue colonized by R. solani. Largest incidences of fusarium wilt corresponded to the lower grain crops in 2003 and 2004. A compound analysis of the three cropping seasons indicated that previous crops with B. brizantha and the B. brizantha-corn consortium were efficient in reducing root rots by R. solani and F. solani f. sp. phaseoli. For fusarium wilt control, in addition to the previous crops with B. brizantha, millet showed good results. Previous cropping with C. cajan and C. spectabilis were consistently associated to the largest disease índices of all diseases studied here. Cropping systems did not affect the severity of root rot by F. solani f. sp. phaseoli, while the incidence of fusarium wilt was generally higher in the NT system, compared to the CC cropping system.

ASSUNTO(S)

plantio convencional. no-till cropping fusarium oxysporum f. sp. phaseoli plantio direto fusarium solani fs. phaseoli fusarium solani fs. phaseoli fungos de solo soil fungi root rot crop rotation fusarium wilt fusarium oxysporum f. sp. phaseoli ciencias agrarias murcha-de-fusário rhizoctonia solani conventional cropping. podridão radicular rhizoctonia solani rotação de culturas

ACESSO AO ARTIGO

Documentos Relacionados