Morphological variability among isolates of Alternaria brassicae (Berk.) Sacc. causing leaf blight of mustard

Abstract

Indian mustard (B. juncea) is a crop of tropical as well as temperate zone, which is grown during rabi season. Alternaria blight disease caused by A. brassicae (Berk.) Sacc. is one of the most important disease of Indian mustard. Twenty isolates of A. brassicae were collected from different divisions of Madhya Pradesh to identify the morphological variation. All the isolates showed high level of variability in vitro in respect of conidial length, width, beak length and number of septa. The conidial length and width ranged from 61.6 to 126.3 µm and 9.7 to 16.9 µm respectively and beak length of conidia ranged from 43.0 to 74.3 µm in different isolates of A. brassicae. The number of horizontal septa and vertical septa ranged from 4.6 to 7.6 and 0.3 to 2.6 respectively.