Efficacy of plant-derived essential oils in post-harvest management of anthracnose disease on mango fruits

Abstract

The harmful effects of chemical pesticides have elicited the evolvement of eco-friendly natural products in plant disease management. This study evaluated the antifungal activity of six plant-based essential oils (EOs) for the management of anthracnose disease on infected mango fruits. The pre-characterized EOs were assessed at seven concentrations which varied between 50 and 2000 (µL/L-1 against mycelial growth of Colletotrichum gloeosporioides in vitro and in vivo. Mycelial growth inhibition (MGI), minimum complete inhibition (MCI) and percent conidia germination (PCG) were determined based on standard procedures. The in vivo trial tested the ability of EOs to mitigate anthracnose disease development on inoculated but treated fruits. The EOs of clove (Syzygium aromaticum), and thyme (Thymus vulgaris) had 100% MGI, attained MCI at 1000 µL/L-1 and had zero PCG. These were significantly (P<0.05) higher than the other treatments including metalaxyl fungicide, the positive control. Although absolute disease control could not be achieved using the EOs in vivo, anthracnose incidence was, however, significantly reduced to between 62.8 and 92.5% in artificially inoculated and treated mango fruits. EOs from S. aromaticum and T. vulgaris at a concentration of 2000 µL/L-1 were more effective than metalaxyl fungicide in reducing anthracnose disease development on inoculated mango fruits. They recorded percentage control of 87.5% and 92.5%, respectively. These findings imply that the use of clove and thyme EOs as antifungal agents have potential of replacing the indiscriminate application of metalaxyl and other synthetic fungicides in mango orchards and postharvest preservation against anthracnose disease.