In vitro assessment of chitosan and essential oils for the control of two pathogen species of Colletotrichum isolated from avocado (Persea americana Mill)

Abstract

The antifungal activity of chitosan, essential oils (cinnamon and eucalyptus) and their combination were evaluated against two pathogens Colletotrichum acutatum and Colletotrichum gloeosporioides isolated from avocado (Persea americana Mill). Chitosan was used at different concentrations (0.1, 0.5 and 1.0%). The concentrations of essential oils evaluated were 0.1, 0.5 and 2.0% (eucalyptus and cinnamon). The effect of the combination of chitosan with the essential oils was evaluated using the most effective concentrations of chitosan (0.1 and 0.5%) and the essential oil with the highest inhibitory effect (2%).The treatments of chitosan and essential oils were partially effective against fungal development by inhibiting mycelial growth in a range of 17 to 21% and 18 to 50%, respectively. The mycelia growth of both strains was totally reduced by the application of chitosan (0.1%) with cinnamon essential oil (2%), however; the combination of chitosan with eucalyptus essential oil was not effective. To our knowledge this research is the first that reports chitosan resistant strains of Colletotrichum isolated from avocado fruits.