Isolation and Identification of Pathogenic Fungi ( <i>Colletotrichum nymphaeae</i> and <i>C. siamense</i> ) From Avocado and Sensitivity to Essential Oils From <i>Pelargonium graveolens</i> or <i>Cordia verbenacea</i>

ABSTRACT The effective control of post‐harvest diseases caused by phytopathogenic fungi is essential to guarantee the quality and productivity of cultivated fruits, motivating the search for alternative and sustainable methods, such as using essential oils (EOs) from unconventional food plants. The objective of this work was to isolate, identify and evaluate the pathogenicity of the causal agents of anthracnose associated with post‐harvest diseases of avocado fruits and to evaluate the potential of EOs from Pelargonium graveolens (geranium) and Cordia verbenacea (black sage, erva baleeira) in controlling the disease. Colletotrichum nymphaeae (UCBV 362) was used from a previous work of ours, and C. siamense (UCBV 136) was isolated from fruits with lesions characteristic of anthracnose. The antifungal activity of geranium and black sage EOs was evaluated at various concentrations. The EOs were evaluated by gas chromatography–mass spectrometry, and 58 components were identified in geranium and 57 in black sage. Pathogenicity testing of the fungal isolates and phylogenetic identification were carried out. Both caused typical anthracnose lesions on avocado fruits. The EOs evaluated showed fungicidal activity at a concentration of 0.25% for geranium and 4.0% for black sage to control Colletotrichum spp. Geranium oil exhibited a greater reduction in mycelium for the two fungi, UCBV 362 and UCBV 136, with the latter showing 100% inhibition. This demonstrates the potential application of EOs as an alternative control method with low environmental impact for controlling anthracnose in avocado.