Fungi Associated with Commercial Kidney Bean Seed and their Pathogenicity to Young Seedlings of Kidney Bean

Abstract

Eighteen to 23% of commercial kidney bean seeds tested failed to emerge, and 7.5-14.5% of them produced diseased seedlings when seeded in pasteurized soil. Rhizoctonia solani or Colletotrichum lindemuthianum were isolated from these diseased seedlings. Fungi associated with 3 different lots of surface-sterilized commercial kidney bean seeds (variety Topcrop) were examined to study fungal flora of these seeds.A total of 1, 036 fungal isolates obtained from 6, 390 seeds of these 3 seed lots were classified into 24 genera. The major 5 genera were Alternaria, Fusarium, Colletotrichum, Chaetomium, and Rhizoctonia, making up 86% of the total isolates.Kidney bean plants became diseased in the pasteurized soil artificially infested with Colletotrichum lindemuthianum, Rhizoctonia solani or Macrophomina phaseoli isolated from these seeds. Fusarium oxysporum showed very weak pathogenicity.One per 22-41 commercial kidney bean seeds was infected with at least one of the aforementioned pathogenic fungi.