<em>In vitro</em> study of selected essential oils against <em>Colletotrichum</em> sp. and <em>Lasiodiplodia</em> sp. causing postharvest diseases in papaya

Abstract

Anthracnose caused by Colletotrichum sp. and stem-end rot (SER) caused predominantly by Lasiodiplodia sp. are common postharvest diseases affecting papaya in Sri Lanka and are currently managed by synthetic chemicals which are hazardous. Use of essential oils (EOs) is considered a non-hazardous alternative. This in vitro study investigated the antifungal potential of selected EOs against anthracnose and SER pathogens isolated from papaya var. ‘Red Lady’.A poisoned food bioassay was carried out to evaluate the antifungal effect of EOs (Cardamom, citronella, orange, mustard and lemon). Colony diameter was taken as a measure of growth. Bioassays consisted of EOs at 500, 750, 1000 μl l-1 with untreated control, three replicates and three separate trials. Cardamom (1000 μl l-1) and citronella (750 μll-1) significantly (P<0.05) inhbited Colletotrichum sp. and Lasiodiplodia sp. from papaya. According to GC-MS, higher percentages of antifungal geraniol, geranyl acetate are present in citronella while a-terpinyl acetate, 1, 8-cineole are present in cardamom oil.

Keywords

• papaya, anthracnose, stem-end rot, essential oils, poisoned food bioassay