Preparation of ready-to-use formulations from clove oil and their antifungal activity against Colletotrichum gloeosporioides, the cause of post-harvest anthracnose disease in mango

Clove oil has demonstrated insecticidal, antimicrobial, antifungal, and nematicidal activity, but its use is limited due to its insolubility in water, high volatility, rapid oxidation, and degradation upon exposure to air. To overcome these constraints, an experiment was conducted to prepare water-soluble formulations from clove oil and evaluate their antifungal activity against Colletotrichum gloeosporioides, the causative agent of post-harvest anthracnose disease in mango. The main challage during the study was to prepare water souble and ready to use formulation from clove oil. In vitro testing showed that all concentrations of clove oil tested resulted in 100% inhibition of C. gloeosporioides. Ready-to-use formulations were prepared by mixing clove oil with various adjuvants, including Tween 20, Tween 80, silicon antifoaming agent, castor oil, xanthan gum, and gum arabic. Of the formulations prepared, two were found to be water-soluble: CT-20 (20% clove oil + 70% Tween 80 + 10% water) and CT-10 (10% clove oil + 80% Tween 80 + 10% water). The physical parameters of both CT-20 and CT-10 met the criteria for EC formulations according to World Health Organization (WHO) specifications (2016). Of the two water-soluble formulations, CT-20 at 0.5% and higher concentrations resulted in 100% inhibition of C. gloeosporioides. The study highlights the potential of clove oil as a natural alternative to chemical pesticides for controlling post-harvest anthracnose disease in mango caused by C. gloeosporioides. The preparation of water-soluble formulations from clove oil will also help to overcome the limitations of clove oil’s water insolubility, high volatility, rapid oxidation, and degradation on exposure to air.