Abstract

Alternaria species, ubiquitous post harvest pathogens, contribute to the spoilage of 20 to 40% of the agricultural output. Alternaria usually attacks aerial parts of its host and symptoms appear as small, circular, dark spots.  Control of this pathogen has become an obligatory requirement. In the present study, two species of Alternaria (Alternaria alternata andAlternaria tenuissima) were selected on the basis of their ability to cause economically important plant diseases. These species were treated with aqueous and methanol extracts as well as essential oil of Cymbopogon citratus L. (lemongrass) in liquid malt extract medium using different concentrations (1, 2, 3 and 4%). Bioassays revealed that among aqueous and methanol extracts; methanol extract caused maximum inhibition of both the Alternaria species at high concentration of 4% after 5 and 10 days of incubation period. A. alternata displayed maximum inhibition of 100% at higher concentration of 4% after 5 days and 94% after 10 days of incubation. In contrast to this, A. tenuissima exhibited 90% inhibition after 5 days and 92% after 10 days at higher concentration (4%). Essential oil of lemongrass proved the most effective as it induced complete inhibition of both fungal species at all concentrations. This study concludes that aqueous and methanol extracts of C. citratus possess the ability for substantial inhibition in growth of A. alternata and A. tenuissima.

Key words: Antifungal activity, Cymbopogon Citratus, aqueous and methanol extract, essential oils.