Antifungal effects of plant essential oils against Colletotrichum gloeosporioides, the fungus associated with citrus twig blight

Twig blight is the most common disease of citrus species caused by Colletotrichum gloeosporioides in the Vidarbha region of Maharashtra State, India, resulting in canopy reduction and fruit retention in orchards. The poison food method and the volatile phase effect were used in this work to evaluate nine essential oils for their antifungal efficacy against C. gloeosporioides at levels of 0.1, 0.5, and 1%. The essential oils studies revealed a broad spectrum of inhibitory activity against C. gloeosporioides, even at the lowest dose. The poison food method revealed that the essential oils of citronella, lemongrass, and garlic were more efficient and produced 100% inhibition at the concentrations tested. The promising results of the volatile phase method also show that lemongrass, citronella, palmarosa, and garlic oils all strongly inhibited (100%) the pathogen at the concentrations tested. This demonstrates the volatile nature of these essential oils. The current studies also revealed that the percentage of inhibition was dose-dependent, with higher concentrations resulting in greater inhibition.