Antifungal activity of selected aromatic and volatile oils and plant extracts on putative plant pathogens

Abstract

A range of aromatic and volatile plant oils (0.1-3% concentration) were shown to inhibit spore germination of putative pathogens isolated from black pepper, cinnamon and turmeric. Cinnamon and clove bark and leaf oils were more efficient inhibitors than the synthetic fungicide Amistar TM used at recommended field concentrations. Cinnamon oils were usually completely inhibitory of spore germination at low concentrations. Garlic oil completely inhibited Phoma, but was less effective on all other fungal species. Oils of lemon grass leaf, lesser galangal rhizome, cardamom seed, and lemon myrtle leaf restricted spore germination at relatively high concentrations (0.5-1%). Lemongrass leaf oil completely inhibited spore germination of Pestalotiopsis cf. versicolor isolated from cinnamon leaves at all concentrations tested. Extracts from galangal rhizomes and cardamom leaves inhibited spore germination. Ethanol extracts had a greater ability to inhibit spore germination than corresponding water extracts. Ethanol extracts from galangal stem and cinnamon bark were particularly inhibitory. Meanwhile, cinnamon bark extract tended to inhibit both putative pathogens and saprophytic fungi but it was less efficient on Pestaiotiopsis sp. isolated from cinnamon leaves.