Introduction.

Costa Rica ranks among the world’s leading producers and exporters of pineapple; however, production and post-harvest handling are hampered due to phytosanitary problems caused by fungi of the genus Fusarium. Objective. To determine the pathogenicity of different Fusarium species associated with the pineapple plant and fruit, and their frequency in the main production areas of Costa Rica. Materials and methods. The experiments were conducted at the University of Costa Rica, San Jose, from 2015 to 2019. Pathogenicity tests were carried out using inoculation with six Fusarium species in bracts, peduncles, and fruits of pineapple, and were verified using Koch’s postulates. Through the collection of 120 isolates, the frequency of Fusarium species in the production areas was established. Results. All Fusarium species caused damage to bracts. The largest lesions were caused by F. oxysporum. In fruit, internal lesions were observed in the pulp with F. ananatum, and a correlation between lesion size and the concentration of inoculated conidia was found. In the peduncle and pulp, lesion diameter varied among Fusarium species. In terms of species frequency, all Fusarium species were present in the Huetar Norte region, and F. ananatum was more abundant in all production regions, except the Brunca region. Conclusions. All the species analyzed were pathogenic in the pineapple crop, in bracts, peduncles, and fruit. F. oxysporum and F. ananatum caused the greatest lesions. The presence in all pineapple-growing regions, the pathogenic potential, and the production of mycotoxins determine the importance of taking precise measures to control and prevent the spread of species from this genus.