Antifungal Effect of Citronella Essential Oil Against Colletotrichum capsici Causing Anthracnose Disease in Green Chili Pepper

Abstract

Green chili pepper is one of the most valuable crops in the Philippines and is extensively cultivated throughout the world due to its versatility. However, its production is affected by pests and diseases, particularly anthracnose diseases caused by Colletotrichum capsici, which is one of the most destructive pathogens of this fruit, reducing the crop’s yield and sustainability. With this, several studies explored the antimicrobial activities of plant-derived essential oils (EOs), and one of them is the citronella (Cymbopogon nardus) oil (CO), and its potential as an eco-friendly alternative to synthetic pesticides. However, limited studies were conducted on the phytotoxicity level of citronella oil and its antifungal effects against anthracnose disease of green chili pepper. Therefore, this study was conducted to determine the non-phytotoxic level of CO and evaluate its effects against the symptom development of anthracnose disease. A phytotoxicity test was conducted, and the in vivo antifungal potential of non-phytotoxic CO concentrations was evaluated against the disease caused by C. capsici. All tests were replicated four times with five samples per treatment, and arranged in a Completely Randomized Design (CRD). The phytotoxicity test resulted that below 0.7% CO concentrations were non-phytotoxic, while 0.8% to 2% exhibited discoloration on the fruits’ epidermis. Subsequently, non-phytotoxic 0.5% to 0.7% CO inhibited the growth and development of C. capsici, implying that its effects were in a dose-dependent manner. Hence, further studies may evaluate the long-term and potential synergistic effects of CO with other natural antifungal agents for enhanced efficacy on various crops and under different conditions.