Abstract

Leaf spot disease of Aloe vera caused by Alternaria alternata (Fr.) Keissler agg. had high variability among different isolates. This study was conducted on pathogenicity, cultural and physiological (temperature and pH) characters. The disease incidence was maximum in Kottampatti of Madurai District (64.92 per cent) of Tamil Nadu, India followed by Sindhalachery of Theni District ( 58.83per cent). Carrot dextrose medium favoured the highest mycelial growth of the pathogen both in solid (8.48cm) and liquid (2.08g/100ml) state. The thermal death point and pH for the growth of A. alternata (Fr.) was 47oC and 5.5 pH respectively. The isolates of A. alternata differed in length, width and beak of conidia .

Keywords: Leaf spot, Aloe vera, cultural characters, pH, solid and liquid media