First occurrence of Sclerotium rolfsii associated with collar and root rot disease of faba bean and its in vitro chemical control

Abstract

Faba bean (Vicia faba L.), a promising grain legume, widely grown in central and northern part of Bangladesh. Disease symptoms resembling to collar and root rot was observed in an experimental field of Bangladesh Agricultural University, Mymensingh, Bangladesh. Disease incidence was ranged between 11–19%. Water-soaked sunken lesions were appeared on the collar region followed by the expansion of rotten areas along with white mycelial mass. The associated pathogen was isolated and identified as Sclerotium rolfsii (Teleomorph: Athelia rolfsii) based on the morphological characteristics and sequence analysis of ITS regions. The isolates grew well in both PDA and OMA media but optimum radial growth (3.31 cm/day) was observed in PDA media. The optimum temperature and pH for radial growth were 30°C and 7.0, respectively. Host range assay revealed that S. rolfsii isolates were strongly virulent to several other important crops such as tomato, brinjal chili, pea and chick pea indicating its potential threat to future agricultural production. Although the isolates were sensitive to Amistar Top, Score and Provax fungicides but Provax was more effective to inhibit the mycelial growth of S. rolfsii at 10 ppm. To best of our knowledge, this is the first confirmed report of S. rolfsii causing collar rot of faba bean in Bangladesh and their in vitro chemical control.