Isolation and Identification of Fungi Causing Diseases in Coffee Plantations and their Susceptibility to Plectranthus amboinicus

Coffee is one of the most important crops globally; however, it is not immune to diseases caused by various organisms that can reduce the quality and yield of its products. Therefore, the objective of this study was to isolate and purify phytopathogenic fungi from coffee crops to evaluate the fungicidal potential of Plectranthus amboinicus extract and compare its effectiveness with Origanum vulgare, which has proven efficacy against various pathogenic fungi and bacteria. The study was conducted on the Limani coffee variety in south-central Puerto Rico. In the field, Coffea arabica var. Limani plants exposed to different light conditions and exhibiting symptoms of fungal infection were selected. In the laboratory, the phytopathogenic fungi were isolated and purified, and morphologically identified using taxonomic keys. Additionally, an aqueous extract of P. amboinicus was prepared for disk diffusion testing to compare its effectiveness with a commercial oregano oil and a carvacrol standard. The phytopathogenic fungi Cladosporium, Aspergillus, and Fusarium were isolated. In the disk diffusion test, the results showed a significant difference in the ability to inhibit mycelial growth of the isolated fungi when using oregano essential oil or carvacrol (p ≤ 0.05). The P. amboinicus extract showed no inhibitory capacity for any of the samples. The use of essential oils with volatile compounds such as carvacrol can be incorporated into a preventive management plan for postharvest diseases. P. amboinicus was not effective in controlling Cladosporium, Aspergillus, and Fusarium isolated from coffee beans. Further bioprospecting of plants that produce secondary metabolites with potential for the treatment of fungal diseases is considered necessary.