First report of Alternaria alternata causing leaf spot on Aloe barbadensis in India

Abstract

Aloe (Aloe barbadensis), an important medicinal plant grown in the state of Tamil Nadu, India has suffered heavy losses due to a leaf disease in 2006. The symptoms observed were small, circular to oval dark brown necrotic sunken spots located mostly on the leaf tip, with average diameter of 1.0 mm and reaching 3.0 mm. The pathogen was isolated and identified as Alternaria alternata and the pathogenicity was established. The conidiophores were branched, straight, golden brown in colour, measuring 15 µm long and 2–6 µm thick. The conidia were golden brown in colour, produced in long branched chains, obclavate in shape, with short conical flask. The literature indicates that this is the first report of a leaf spot disease of aloe in India.